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Influence of the dendritic microstructure and �-Al5FeSi phase on the
wear characteristics in a horizontally solidified Al-7Si-0.4Mg-1.2Fe alloy
Angela Vasconcelos, Hugo Azevedo, André Barros, Otávio Rocha,
Mirian Melo
PII: S2352-4928(21)00091-X
DOI: https://doi.org/10.1016/j.mtcomm.2021.102099
Reference: MTCOMM 102099
To appear in: Materials Today Communications
Received Date: 8 October 2020
Revised Date: 11 January 2021
Accepted Date: 28 January 2021
Please cite this article as: Vasconcelos A, Azevedo H, Barros A, Rocha O, Melo M, Influence
of the dendritic microstructure and �-Al5FeSi phase on the wear characteristics in a
horizontally solidified Al-7Si-0.4Mg-1.2Fe alloy, Materials Today Communications (2021),
doi: https://doi.org/10.1016/j.mtcomm.2021.102099
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https://doi.org/10.1016/j.mtcomm.2021.102099
https://doi.org/10.1016/j.mtcomm.2021.102099
1 
 
Influence of the dendritic microstructure and β-Al5FeSi phase on the wear 
characteristics in a horizontally solidified Al-7Si-0.4Mg-1.2Fe alloy 
Angela Vasconcelosa, Hugo Azevedob, André Barrosc, Otávio Rochab, Mirian Meloa* 
 
a Federal University of Itajubá, Institute of Mechanical Engineering - UNIFEI, Itajubá, 37500-903, MG, Brazil 
b Federal Institute of Education, Science and Technology of Pará-IFPA, Belém, 66093-020, PA, Brazil 
c Department of Manufacturing and Materials Engineering, University of Campinas-UNICAMP, 13083-860 
Campinas, SP, Brazil 
 
*Corresponding author – E-mail address: mirianmottamelo@unifei.edu.br 
 
Graphical Abstract 
 
 
Abstract: In this work an Al-7Si-0.4Mg-1.2Fe alloy (wt.%) was subjected to a horizontal solidification 
experiment using a water-cooled solidification device equipped with thermocouples to obtain temperature vs. 
time data which in turn allowed solidification thermal parameters, such as growth and cooling rates (VL and TR, 
respectively), to be determined. In turn, tribological behavior of samples with different secondary dendritic 
spacing (2) and β-Al5FeSi platelets length (βFe) were assessed by means of dry sliding wear testing performed in 
a rotating fixed ball machine, with wear volume and rate (WV and WR, respectively) being the two main 
investigated wear parameters. Quantitative metallography by optical and scanning electron microscopy along 
with energy dispersive X-ray spectroscopy enabled both as-cast microstructures and worn craters to be 
characterized. More significant variations in wear resistance of the investigated alloy were found for ranges of 2 
and βFe that lie within 12-20 µm and 14-36 µm, respectively, with the coarsening of the microstructure 
constituted by Al-rich primary phase dendrites surrounded by α-Al + Si + -Mg2Si + β-Al5FeSi eutectic 
structures favoring reduced WV and WR values. For 2 and βFe values higher than 24 and 48 µm, respectively, 
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both WV and WR stabilize assuming constant values that depend on the sliding distance. In addition to power 
type equations relating 2 and βFe to VL and TR, mathematical expressions for variations of WV and WR with 2 
and βFe are also proposed. Finally, a comparative analysis with the literature is presented. 
Keywords: Horizontal solidification; Microstructure; β-Al5FeSi phase; wear feature, AlSiMgFe alloys 
 
 
 
 
 
 
1. Introduction 
Technologies to optimize the benefits of recycling of aluminum alloys for casting and 
mechanical forming processes have been widely reported in the scientific community mainly due to 
the fact that the energy required to recycle is significantly less than that of processes used to obtain the 
same amount of primary alloy thus characterizing an outstanding solution for environmental appeals 
[1,2]. However, one of the greatest challenges facing recycling industries refers to the incorporation of 
iron into aluminum scraps which in turn can lead to the inevitable formation of Fe-intermetallic phases 
during liquid-solid transition [3-6]. Indeed, several Fe-rich intermetallic compounds (IMCs) such as -
Al8Fe2Si or -Al15(Fe,Mn)3Si2, β-Al5FeSi, -Al4FeSi2, -Al7Cu2Fe and -Al8Mg3FeSi6 can nucleate 
and growth during solidification of recycled Al alloys depending not only on the alloy composition, 
but also on the thermal processing conditions [7-11]. Therefore, the optimized design of recycled Al 
alloys for a particular application presumes a detailed understanding of the role of these Fe-rich phases 
on the resulting properties. 
Among the most common Fe-rich IMCs present in the as-cast microstructure of commercial 
Al alloys, β-Al5FeSi phase has been recognized as one of the most undesirable when a superior 
mechanical behavior that associates high tensile strength with good ductility is required [5,12-14]. 
Commonly with the morphology of needles-like faceted plates, such microstructural phase favors 
stress concentrations at its sharp points. In addition, since β-Al5FeSi particles are brittle and hard, their 
presence in microstructure is detrimental to the machinability of castings. Hence, several studies have 
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been dedicated to continuing to better understand how nucleation of the needles-like β-Al5FeSi phase 
and mechanisms of change in its morphology during solidification can affect the mechanical behavior 
[22-25]. Basak and Babu [23], for example, have depicted that morphological change of β-Al5FeSi-
phase and Si could help recovering the strength and ductility in the recycled Al-Si alloys having high 
Fe content. According to Li et al. [13], although the Fe has a deleterious effect on both ultimate tensile 
strength (UTS) and ductility, mainly due to the presence of the β-Al5FeSi phase, Fe additions up to 
0.8% have increased the yield strength (YS) of Al7Si3Cu-(Mn;Fe;Sr) alloys, deducing an increase in 
the hardness. Studying Al-9Si-xFe alloys (x = 0.1, 0.4, 0.8 and 1.2wt.%) processed by chill casting, 
Malavazi et al. [14] reported higher UTS and YS values for Fe contents equal to 0.4 and 0.8wt.% Fe, 
respectively, as well as a greater amount of β-Fe phase to 1.2 wt.% Fe. Ceschini et al. [12] state that Fe 
additions up to 0.5% in Al10Si2Cu alloy (wt.%) besides promoting the presence of the needle-like β 
phase, also induce a slight increase in fatigue resistance. Additionally, they found that the presence of 
-Al15 (Fe,Mn)3Si2 phase, resulting from Mn addition, has influenced the crack path, increasing in turn 
the resistance to fatigue. 
Although the deleterious effects on the tensile properties (UTS and elongation), the wear 
performance of Al-Si alloys with Fe addition has attracted the attention of researchers in recent years 
[15-21]. For instance, Ji et al. [5] have reported for Al-Mg-Si-Mn and Al-Mg-Si die cast alloys that 
the increase in Fe concentration has reduced significantly the ductility, but accompanied by an 
improvement in yield stress (YS). Taghiabadi et al. [15] analyzed the wear behavior of Al-Si alloys 
due to the presence of the needles-like β-Al5FeSi phase, and the results showed that an increase in Fe 
from 0.15wt.% in the base alloy to about 0.7wt.% increased the hardness and improved wear 
resistance by about 10% under applied loads of 20 and 40N. The Fe addition up to 2.5wt.% has 
increased the hardness, but has decreased wear resistance. The authors [15] have controlledthe 
negative influence of the β phase through combined effects of high cooling rate (TR) and chemical 
modification by Sr. In turn, Taghiabadi and Ghasemi [16], investigating the dry sliding wear behavior 
of hypoeutectic Al-Si-(xFe) alloys, noted that as the amount of Fe was increased to 0.7 wt.%, an 
improvement of 10% was observed in the wear resistance under applied loads of 20, 30 and 40N. 
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However, for Fe additional contents up to 1.8wt.%, the wear resistance was lowered by about 30, 35 
and 55% under applied loads of 20, 30 and 40 N respectively. Abouei et al. [17] have evaluated the 
solidification conditions and Mn addition on the wear behavior of Fe-rich eutectic Al-Si piston alloy, 
and reported that the combined effects of high TR with Mn addition have resulted in the formation of 
finer α-IMCs and, in turn, have improved the wear performance of the alloy. Saghafian et al. [19] have 
investigated the effects of Fe addition and solidification conditions on the Al-Si eutectic alloy, and 
reported that the presence of Fe may give rise to the formation of a needle-like β-Al5FeSi phase, 
whose fragile nature has led to a decrease in the mechanical characteristics of piston alloys, including 
wear resistance. However, the addition of Mn/Fe in a ratio of 1/2 has modified the needle-like β phase 
in alloys containing up to 1.2wt.%. 
Bidmeshki et al. [20] have studied the effect of Mn addition on both Fe-rich IMCs and the 
wear behavior of Al-17.5wt.%Si hypereutectic alloys, and have shown that addition of 1.2wt.%Fe to 
the base alloy increased the wear rate due to the formation of needles-like β-Al5FeSi intermetallic. On 
the other hand, the introduction of 0.6wt.%Mn to the Fe-rich alloy changed the needles-like β 
morphology and, as a consequence, reduced the negative effect of Fe, but the Mn addition up to 
0.9wt.% has not prevented the formation of needles-like β [20]. More recently, Kaiser et al. [21], 
assessing the mechanical and wear behavior of hypereutectic in Al-Si-(Fe;Ni;Cr) automotive alloys, 
have depicted that Fe addition has improved the hardness of all the studied alloys due to formation of 
hard β-Al5FeSi phase, but it has reduced YS, UTS and wear resistance. Pouladvand et al. [26] have 
carried out investigation with Al-xSi-1.2Fe(Mn) (x=5-13 wt.%) alloys and according to the results, in 
the Si range of 5-9 wt.%, Fe-impurity promotes the formation of finely distributed β-Al5FeSi IMCs in 
the matrix increasing its hardness and potential to support the tribolayer leading to the improvements 
in wear characteristics. According to the authors [26], the substitution of fine β-Al5FeSi platelets by -
Fe Chinese scripts in Al-(5-9)Si-1.2FeMn (wt.%) alloys reduces the wear resistance, whereas the 
formation of star or polyhedral-like -Fe compounds in Al-(9-13)Si-1.2FeMn alloys improves the 
wear resistance. 
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As can be seen, although the literature presents studies on the wear characteristics of Fe 
containing Al-based multicomponent alloys, studies on directional solidification with AlSiMgFe 
alloys for recycling purposes are still scarce in the literature, especially as concerns to thermal and 
microstructural analyzes, including the effects of the growth and cooling rates on the dendritic 
microstructure and, in turn, on the wear parameters. In addition, directional solidification works that 
perform β-Al5FeSi particle analyzes are rare in the literature to evaluate the effects of thermal and 
microstructural solidification parameters on the length and distribution of β-Al5FeSi platelets IMCs in 
the as-cast microstructure of Al-Si casting alloys. 
An important aspect to be considered is about the solidification direction. Upward 
solidification (with melt on top of the solid) is both thermally and solutally stable for alloys in which 
the rejected element at the solidification front induces a local liquid that is denser than the melt [27]. 
In the case of downward vertical solidification, melt convection arises during the process [27]. On the 
other hand, when the chill is placed on the side of the mold (in the horizontal solidification), the solid 
grows perpendicularly to gravity and convective flow becomes even more complex since two-
dimensional 2-D (in some cases 3-D) assumptions must be considered to formulate the inherent 
transport phenomena [28,29]. Under horizontal growth conditions, both thermal and composition 
gradients may occur in the melt bath resulting in quite complex movements by convection within the 
fluid, thereby leading to effects that may also have a significant impact on solidification thermal 
variables, solid/liquid (S/L) interface morphology, resulting structures, and segregation [28,29]. 
Thus, this work aims to present a study on the roles of the thermal parameters, dendritic 
microstructure length scale (represented by the secondary dendritic spacing - λ2) and β-Al5FeSi phase 
feature on the wear resistance in a horizontally solidified Al7Si0.4Mg1.2Fe alloy. 
 
2. Experimental procedure 
 The Al7Si0.4Mg1.2Fe (wt.%) alloy investigated in this work was prepared from the as-cast 
ingot of a base alloy whose chemical composition furnished by the Brazilian Military Material 
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Industry (IMBEL) is shown in Table 1. It has been carried out by an optical emission spectroscopy, 
SpectroMaxx model. Fe powder of high purity was added to the base alloy in the stoichiometric 
proportion to achieve the desired Fe solute content (1.2wt.%). The investigated alloy has been 
subjected to thermal analysis through a slow cooling in the crucible to check the liquidus and solidus 
temperatures. The results will be presented and analyzed in the Results and Discussions section. 
Table 1. Chemical analysis of the base A356 alloy used in this work to elaborate the investigated alloy. 
Element (wt.%) 
Al Si Fe Mg Cu Mn Cr Zn Ti 
Balance 6.88 0.153 0.332 0.074 0.0005 0.0005 0.0010 0.0020 
 
Figure 1a presents a complete scheme of the furnace used in the solidification experiments to 
obtain the as-cast ingot of the investigated alloy, as well as the details of the water-cooled horizontal 
solidification device and the positioning of thermocouples (5, 10, 15, 20, 30, 50 70 e 90 mm), type K, 
from the heat transfer surface (mold plate) of the horizontal ingot mold, as seen in Figure 2b. The data 
generated by reading the thermocouples have been processed by software OriginPro 2020 and used to 
determine the transient thermal parameters during horizontal solidification. Two transient thermal 
parameters were studied herein, which are: tip growth rate (VL) and solidification cooling rate (TR). 
Whereas VL represents the rate of advance of the liquidus isotherm into the liquid, TR expresses the 
first time-derivative of the thermal profiles provided by the thermocouples (slope of the cooling curve) 
at the liquidus temperature. Temperature-time data acquired during solidification considering the 
centerline corresponding to the longitudinal axis of the casting were used to generate a plot of position 
from the metal-mold interface as a function of time corresponding to the liquidus front passing by each 
thermocouple. A curve fitting technique on such experimental points generates power functions of 
position as a function of time. The first time-derivative of this function yields values for VL. The TR 
profile was determined using thermal data recorded immediately after the passing of the liquidus front 
by each thermocouple, so that calculations of the slope of the cooling curve at the liquidus temperature 
could be performed. More details on the canting assembly applied as well as the working principle 
have been described in previous studies [28-31]. 
 
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Figure 1. (a) Complete scheme of the solidification furnace, with detailsof the horizontal water-cooled 
device and (b) positioning of the thermocouples in the ingot. 
The casting ingot of Al7Si0.4M1.2Fe (wt.%) alloy, obtained from the horizontal solidification 
experiment, was sectioned longitudinally, sanded to # 600 and then immersed in regal water (HNO3 + 
HCl) to reveal the macrostructure, as shown in Figure 2a. Removal of samples for microstructural 
analysis can be seen in Figure 2b. The microstructure was revealed using the Keller reagent (10 ml of 
HF, 15 ml of HCl, 25 ml of HNO3 and 50 ml of distilled water). 
Measurements of 2 and β-Al5FeSi phase length (βFe) were performed in selected longitudinal 
sections of as-cast samples from the cooled base at 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90mm. Next, 
all the average values of 2 and βFe, in turn, were correlated with VL and TR. Image processing 
MOTIC system and the Image J software were used to measure 2 and βFe (~20) independent readings 
for each selected position. In addition, microstructural characterization was carried out using a 
scanning electron microscope (SEM TESCAM, VEGA LMU) coupled to an energy-dispersive X-ray 
spectrometer (EDS, AZTec Energy X-Act, Oxford). 
 
 
 
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Figure 2. (a) Schematic representation of the as-cast ingot of the investigated alloy, showing the 
longitudinal section for microstructural analysis and (b) techniques applied in the measurement of 2 
and β-Al5FeSi particle length (βFe) 
 
In order to perform tribological analysis by correlating the thermal and microstructural 
parameters with the wear parameters, such as the volume and wear rate (WV and WR), micro-abrasive 
wear tests on as-cast samples of the investigated alloy were carried out, as shown in Figure 3. The 
wear machine used in the experiments is a dry rotary ball type, widely used in recent studies [32-38], 
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as seen in Figure 3a. The samples for the tests were selected in positions 5, 10, 15, 20, 30, 50, 70, and 
90 mm from the cooled base, with dimensions of 15 x 20 mm in cross-sectional area, as shown in 
Figure 3b. Before testing, the samples were sanded to 1200 # and polished in diluted alumina to 1μm. 
The operating principle of the machine as well as the operational conditions to carry out the tests have 
been detailed in recent works [32-38]. 
During dry sliding testing, the rotating sphere composed of AISI52100 microalloyed steel with 
hardness of 850 HV and diameter of 25.4 mm is in direct contact with the surface of the samples. The 
sliding speed used (W) was 0.49 m/s (or W = 370 RPM) and the normal contact load applied to the 
tested part was 0.2 N. The tests were carried out under dry sliding, that is, without an abrasive solution 
to avoid the presence of any interfacial element external to the surface of the samples. In total, each as-
cast sample was tested four times, due to the four times (t) assumed for the tests, equal to 7, 14, 21 and 
28 minutes [37,38]. This has generated caps in the form of worn craters. 
After the tests of all samples were completed, the DIGILAB stereoscope was used to analyze 
the craters and using ImageView image capture software the images of the worn craters were obtained. 
In turn, the craters diameters (D) were measured by the ImageJ software, and from these 
measurements, the WV and WR wear parameters were calculated using Equations 1 and 2, respectively. 
𝑊𝑉 =
𝐷4
64𝑅
 (1) 
𝑊𝑅 =
𝑊𝑉
𝑆𝐷
 (2) 
Where D is the worn crater diameter, as seen in Figure 3b, and R is the ball radius. The diameter was 
measured four times for each worn crater along different radial positions. SD is the sliding distance, 
which has been calculated by: SD = W.t.2R, for the four assumed test times were: 207m, 413m, 620m 
and 827m [32-38]. 
It is important to highlight that in order to avoid interference in the results caused by any 
irregularities in the observed wear craters, duplicates of the tests were carried out and the final 
diameter for each of the positions and times analyzed was determined using the arithmetic mean of the 
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results. In cases where there is a large disparity between the first test and its duplicate, a triplicate was 
performed, and the crater whose diameter showed the greatest deviation was discarded. 
 
 
 
 
 
 
 
 
Figure 3. (a) Schematic representations of: (a) wear machine and (b) obtaining worn craters in as-cast 
samples from the heat transfer surface [32-38]. 
 
3. Results and discussion 
3.1. Thermal and microstructural analysis 
 Figure 4 a presents the results of the thermal analysis of the unsteady-state horizontally 
solidified Al7Si0.4Mg1.2Fe (wt.%) Alloy. The thermal data generated by the 8 thermocouples, as 
shown in Figure 4a, were used to experimentally determine the solidification thermal parameters, VL 
and TR, as can be seen in Figure 4b. From the intersection of the isotherm represented by the liquidus 
temperature (TL) (Fig. 4a), a set of ordered pairs (t, P) were obtained. This allowed generating a power 
type adjustment curve, given by the expression P = 1.65(t)0.75, which was the best possible fit in the 
points observed experimentally. The growth rates were calculated using the d(1.65t0.75)/dt derivative, 
resulting in the expression VL=2.89(P)-0.57. The cooling rates were determined by the dT/dt derivative 
at the times corresponding to the intersections of TL with the temperature profiles generated by each 
thermocouple. Evidently, the cooling water imposed high values of VL and TR close to the heat 
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transfer surface, which decrease along the length of the ingot due to the formation of the solid layer 
during horizontal solidification, as can be seen in Figure 4b. 
 
 
 
 
 
Figure 4. Thermal analysis resulting from the transient horizontal solidification of the investigated 
alloy: (a) thermal profiles for 8 thermocouples and (b) thermal parameters. 
 
 Figures 5 shows the typical solidification structures of the investigated alloy, in macro and 
micro-scales. A microstructural evolution along the ingot shows that the observed dendritic 
microstructure is constituted by a dendritic network. Therefore, finer dendritic microstructures are 
observed for as-cast samples analyzed from the heat transfer interface. Figure 6 shows the results of 
the interconnection of the secondary dendritic spacings (2) with the transient solidification thermal 
parameters. As expected, VL and TR have a high influence on the 2 values, since that lower 2 can be 
observed for positions (P) in the as-cast ingot where VL and TR come to be higher. Power 
mathematical expressions that correlate 2 as a function of VL and TR were generated, represented by 
general equations given by 2=Constant(VL)-2/3 and 2=Constant(TR)-1/3, respectively, which 
characterize 2 dependence as a function of solidification thermal parameters, as shown in Figure 6. It 
is observed that the exponents 1/3 and -2/3 are absolutely in agreement with the experimental 
predictions from the literature [4,39], as well as with the theoretical prediction of Bouchard-Kirkaldy 
[40] which proposed a mathematical approach of 2=f(VL) for binary alloys. It can be also noted that 
the determined power-type equations for the growth 2 as a function of solidification parameters are 
inside the range reported in literature. 
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Figure 5. Typical solidification structures for the Al7Si0.4Mg1.2Fe alloy (wt.%), resulting from the 
unsteady-state horizontal solidification process. 
 
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Figure 6. Experimental laws of secondary dendritic growth as a function of thermal solidification 
parameters. 
 
In order to observe the phase transformations that occur in the solidification path of theAl7Si0.4Mg1.2FE alloy (wt.%), in this work, the pseudo binary phase diagram of the Al7Si0.4MgxFe 
alloy (wt.%) was plotted by the means of the Thermo-Calc computational thermodynamic software, as 
shown in Figure 7a, as well as the experimental cooling curve was generated by slow cooling during 
solidification of the investigated alloy inside the crucible, as seen in Figure 7b. A comparative analysis 
between the main points of phase transformation, represented by the processes (1) to (4) in both 
figures, shows the microstructure evolution during the cooling. The inflection points of the derivative 
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of the experimental curve represent the beginning of precipitation phases new, as shown in Figure 7b. 
It can be noted that the final microstructure of the investigated alloy is constituted by a primary phase 
(Al) consisting of a dendritic network (see Figure 5) and by a mixture of eutectic phases within the 
interdendritic regions composed by the following Mg2Si + β-Al5FeSi intermetallic phases plus 
eutectic Si. 
 
 
 
 
 
 
 
Figure 7. (a) Pseudo binary phase diagram for the Al7Si0.4MgxFe alloy and (b) experimental cooling 
curve of the investigated alloy under slow cooling. 
 
Figure 8 shows two scanning electron micrographs with element mapping by EDS, for two as-
cast samples, from the heat transfer surface. A concomitant comparative analysis between Figures 7 
and 8 confirms that the final microstructure of the investigated alloy consists of a primary phase (Al) 
and a mixture of interdendritic eutectic phases composed of Aleutectic + Si + (Mg2Si + β-Al5FeSi) 
IMCs. It is observed fine eutectic β-Al5FeSi particles within the interdendritic regions surrounded by 
eutectic Si particles for high VL and TR and lower 2, as shown in Figure 8a. In addition, for such 
conditions, fibrous and spheroidal-like eutectic Si has been noted. This is in agreement with the results 
from the literature [28,30,41]. On the other hand, for low VL and TR and higher 2, the eutectic Si 
undergoes from a “spheroidal + fibrous” morphology, to acicular morphology, as well as needle-like 
β-Al5FeSi phase come to precipitate out of interdendritic regions and over the primary dendritic 
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phase, as secondary and primary eutectic reactions, respectively, as can be seen in Figure 8b. 
Malavazi et al. [14] have depicted that both increasing the Fe content and decreasing the cooling rate 
encouraged the platelets-like β-Al5FeSi phase to crystallize independently of silicon. They have also 
reported that the particles formed by the primary eutectic reaction are bigger that those formed by the 
secondary eutectic reaction. 
 
 
 
 
 
 
 
 
Figure 8. Scanning electron microscopy with EDS element mapping for two as-cast samples of the 
investigated alloy in the following positions from the cooled base: (a) 5 mm e (b) 40 mm. 
 As reported, β-Fe IMCs have a strong influence on the mechanical performance of Al-Si-
based casting alloys, thus, knowing the formation of their microstructural characteristics, such as 
length and distribution in the as-csat microstructure, it is of fundamental importance to establish the 
best morphological control process. In this sense, an analysis of needle-like β-Al5FeSi phase of the 
unsteady-state horizontally solidified Al7Si0.4Mg1.2Fe alloy (wt.%) has been carried out and the 
results shown in Figures 9 and 10. As a highlight of the present work, mathematical expressions have 
been proposed which characterize of βFe`s dependence on VL, TR and 2, as seen in Figures 9a and 9b. 
SEM microstructures, seen in Figure 9c for three positions in the ingot from the cooled base, show that 
fine and smaller βFe have been observed for higher VL and TR values and smaller 2, as found by 
Malavazi et al. [14] and Rakhmonov et al. [7]. 
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Figure 9. (a) and (b) Fe particle length (βFe) dependence as a function of the position in the as-cast 
ingot and thermal parameters (VL and TR), respectively, and (c) SEM micrographs, showing the βFe 
variation. 
The occupation of needle-like β-Al5FeSi phase in the final microstructure of the investigated 
alloy, under the assumed solidification conditions, has been determined by the fraction of occupied 
area (%), as shown in Figure 10a. Fraction of occupied area values have been obtained by binarization 
of as-cast microstructures, using Image J software [30,38]. The images shown in Figure 10b refer to 
the original and binarized microstructures for three positions from the heat transfer interface. It is 
verified that there is no linear behavior of β-ICMs occupation on the microstructure, since the 
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occupied fraction presents an inverse variation up to the 40 mm position, assuming minimum and 
maximum values in positions 5 and 40 mm, respectively. From the 40 mm position, the fraction of 
needles-like β phase grows again until 80 mm, as can be noted in Figure 10a. Rakhmonov et al. [7] 
and Narayanan et al. [43] showed that high cooling rates also cause increase in the number density of 
β-Fe needles. It was attributed to the displacement of the nucleation temperature of β-Fe towards lower 
temperatures with increasing cooling rate, thus reducing the time available for the growth of β-Fe 
[7,42]. 
 
 
 
 
 
 
 
 
 
 
Figure 10. (a) Area fraction of occupied area by needle-like β-Al5FeSi particle in as-cast samples 
from the cooled base and (b) original and binarized SEM microstructures for three positions form the 
cooled base. 
 
3.2. Wear behavior analysis 
 Figures 11a and 11b show the results of worn volume (WV) with the variation of the sliding 
distance (SD) and the worn caps (craters) for all samples tested under the assumed conditions. As 
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expected, diameters of worn craters and, consequently, wear volumes have been greater for longer test 
times. It is important to highlight that several scientific researches [32-38, 43-45] have used the micro-
abrasion wear with rotating sphere due to the practicality of the test as well as the fact that it allows to 
analyze the wear mechanisms acting in the tribological system, as well as possible transitions in the 
performance of the formed film in the contact between the body and the counter-body. The sphere 
when rotated produces an impression in the shape of a cap on the surface of the worn sample, as can 
be seen in Figure 11b. This cap or crater is evaluated qualitatively and quantitatively, generating data 
that identify the wear resistance of the tested sample. 
 
 
 
 
 
 
Figure 11. (a) Variation of the worn volume with the sliding distance and (b) worn craters for the four 
assumed test times. 
 
Figure 12 and 13 show the wear volume (WV) and rate (WR) dependences on the secondary 
dendritic spacings and the of the Fe phase length (βFe). Similar behavior of the WV and WR variations 
have been observed, since for all test times an inverse mathematical relationship has been found 
between (WV;WR) x 2 and (WV;WR) x βFe for worn samples closer to the cooled base, for 2 and βFe 
values that lie within the ranges 12-20 µm and 13.8-35.8 µm, respectively. This allowed to propose 
mathematical expressions that characterize the WV and WR variations as a function of 2 and βFe, as 
shown inside Figures 12 and 13. It is important to note that excellent determination coefficients (R2> 
0.7) were achieved for the mathematical equations obtained in the tests times equal to 7 to 21 minutes, 
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which suggests that the proposed expressions for these times represent well the trend of the scattered 
experimental data. In turn, both WV and WR stabilize assuming constant values for 2 and βFe varying 
from 14 to 35.8 µm and 46.8 to 98 µm, respectively.From a concomitant analysis with Figures 10 
and 12, it is observed that finer and smaller needle-like β-Al5FeSi particles are present in greater 
quantity in the microstructure, that is, in a greater fraction of occupied area (see Fig. 10a), significantly 
influencing the lower wear resistance observed in samples closer to the cooled base. Even thpough the 
spherical/fibrous-like eutectic Si present in the finer microstructure, as noted in Figure 8a, this was not 
able to improve the wear resistance. 
Different wear characteristics have been reported by Azevedo et al [38] for the horizontally 
solidified Al7Si0.3Mg0.15Fe alloy, as can be seen in Figure 12a. It can be deduced from the 
comparative analysis that the investigated alloys with Fe contents equal to 1.2wt.% (This work) and 
0.15wt.% [38] show the same wear resistance for times of 7min and 14min, while for longer times (21 
and 28 min) the Al7Si0.4Mg1.2Fe alloy (wt.%) alloy presents low wear resistance (high WR), 
probably due to the comparatively higher amount of the needle-like β IMCs and higher βFe values, as 
shown in Figure 13a and 13b. Under these conditions, when the as-cast surface is subjected to the 
micro-abrasive wear, the caused sliding deformations, the fragile and hard Fe particles are fragmented 
and removed, promoting the instability of the tribolayer and, as a consequence, increasing the wear 
volume and rate. Pouladvand et al. [26] have depicted that the β-platelets are brittle in nature and 
exhibit weak faceted interface with the matrix and, thus, when subjected to the sliding-induced surface 
strains, they are easily fragmented and/or decohered from the matrix, especially for high Si alloys. On 
the other hand, it is seen that the wear resistance of the investigated alloy in this work stabilizes for 2 
and βFe values varying from 14 to 35.8 µm and 46.8 to 98µm, respectively, while in the other [38] it 
decreases with the 2 variation, as seen in Figures 12a. 
In fact, λ2 alone cannot explain the improvement in wear resistance. However, there is a direct 
relationship between λ2 and the length of the Al5FeSi phase [22], as the results found in this 
investigation also reveal, as seen in Figure 9b. Thus, it can be suggested the use of λ2 as a key 
parameter to quantitatively represent the refinement of the microstructure length scale. Experimental 
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equations that relate the quantitative wear parameters to λ2 have also been proposed in previous 
investigations that involved the tribological characterization of Al-based alloys [46,47]. 
 
 
 
 
 
Figure 12. Correlation between worn volume and microstructural parameters: (a) 2 and (b) βFe. 
 
 
 
 
 
 
 
Figure 13. Correlation between worn rate and microstructural parameters: (a) 2 and (b) βFe 
 
The wear futures have been analyzed on worn craters surface by the Figures 13 to 16, wich 
show SEM micrographs with elements microanalysis by EDS for three solidified samples in positions 
from the heat transfer surface, considering two test times, 7 and 28 min, which represent the lesser 
and greater severity conditions, indicated by points 1 and 2 in the corresponding figures, respectively. 
It is observed, from the worn craters, the presence of the wear adhesive and abrasive mechanisms 
acting simultaneously for the two investigated times, with predominance of the adhesive wear, since 
more severely worn regions have been observed on the surfaces of the craters, obviously for the 
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longest test time (28min), as can be seen in Figures 14b, 15b and 16b. Severe wear marks have been 
observed on worn crater surfaces in as-cast samples with coarser microstructures, i.e, low TR and 
higher 2, as noted in Figures 15 and 16. Additionally, an oxide film layer that provides a grease effect 
is expected to form on the sample/sphere interface as a result of the increase in temperature as sliding 
distance increases [49,50]. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Figure 14. Wear characteristics and SEM/EDS analysis for as-cast samples at a position equal to 5mm 
from the cooled base in the following test times: (a) 7min and (b) 28min. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 15. Wear characteristics and SEM/EDS analysis for as-cast samples at a position equal to 
30mm from the cooled base in the following test times: (a) 7min and (b) 28min. 
 
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Fugure 16. Wear characteristics and SEM/EDS analysis for as-cast samples at a position equal to 
90mm from the cooled base in the following test times: (a) 7min and (b) 28min. 
 
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Initially, harder particles in greater quantity, present in the as-cast microstructure, such as 
needle-like β IMCs, are pulled out (or broken), causing severe wear on the surface, and at the same 
time transferred to the test sphere. In this case, adhesive wear has been characterized by high wear 
rates. It is important to note from the element tables, for all cases analyzed, high Fe amounts in the 
regions represented by severe wear (points 2). In turn, the hard particles that have welded to the 
surface of the sphere and, with their rotating movement, scratches or parallel juices have been 
produced on the surfaces of the worn out craters, thus characterizing the abrasive wear. Azevedo et al. 
[38] have suggested for the as-cast samples of the horizontally solidified Al7Si0.3Mg0.15 (wt.%) alloy 
the occurrence of a wear mechanisms transition from adhesive to abrasive, and they have indicated 
that the abrasive wear mode prevails for high TR and lower 2, that is, for finer microstructures. A 
transition of wear mechanism from adhesive to abrasive has also been found by Botelho et al. [37] for 
horizontaly solidified Al3Ni1Bi (wt.%) alloy. 
For commercial alloys it has been well known that the β-Al5FeSi phase is hard and fragile 
compared with the primary Al-rich phase, so that the presence of β particles in the microstructure is 
expected to lead to a general reduction of tensile properties such as ductility and ultimate tensile 
strength (UTS) [48]. It can also be deduced that the ductility may have an inverse behavior with the 
increase of the β phase. Besides, longer intermetallics and coarser dendrite arm spacing formed during 
solidification of high Fe content Al alloys are directly related to a reduction of the tensile properties. 
For an as-cast 356-based alloy with similar composition of the one studied herein, Dong et al. [51] 
have reported UTS values equal to 200 ± 11 MPa and 180 ± 4.9 MPa for 2 values of 26.4 ± 3.6 µm 
and 46 ± 7.3 µm, respectively. As found in this work, for 2 < 20 µm wear resistance decreased as 
microstructure became finer. With this in mind, it can be deduced that wear resistance and tensile 
strength may show an opposite behavior. However, for 2 higher than 24 µm, both wear volume and 
rate (WV and WR, respectively) assume constant values for each sliding distance. Consequently, the 
optimized design of recycled Al alloys assumes a detailed understanding of the role of these Fe-rich 
phases on the resulting properties. Thus, in order to find an optimum combination of wear resistance 
and mechanical properties, we can deduce that: if 2 > 24 µm, mechanical strength assumes 
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dominance since wear response is constant; but in the case of 2 values lower than this one, wear 
response variation becomes a factor that should be taken into account and the experimental 
expressions proposed in this study can be used as a reference. 
 
4. Conclusion 
 The following major conclusions were obtained from the present experimental investigation: 
(1) The typical solidification microstructure has been formed by an Al-rich primary phase, 
consisting of a dendritic network, andby a mixture of interdendritic eutectic phases composed 
of Aleutectic + eutectic Si + (Mg2Si + β-Al5FeSi) IMCs. It has been observed fine eutectic β-
Al5FeSi particles within the interdendritic regions surrounded by fibrous and spheroidal-like 
eutectic Si particles for high TR and lower 2. 
(2) While the needle-like β-Al5FeSi IMCs length (βFe) dependence has been characterized by 
inverse mathematical expressions with VL and TR, the increase in βFe values with increasing 2 
was shown to be directly proportional, that is, smaller βFe were found for higher VL and TR, 
and smaller 2. 
(3) An inverse mathematical relationship has been found between (WV;WR) x 2 and (WV;WR) x 
βFe for worn samples closer to the metal/mould surface, for 2 and βFe values varying from 12 
to 20µm and 13.8 to 35.8 µm, respectively. On the other hand, constant values of WV and WR 
have been observed for 2 and βFe values varying from 14 to 35.8µm and 46.8 to 98 µm, 
respectively. 
(4) From the analysis of the worn crater surfaces, it has been noted the presence of the wear 
adhesive and abrasive mechanisms acting simultaneously, with predominance of the adhesive 
wear. 
(5) Finer as-cast microstructures have shown lower wear resistance due to the presence of the 
largest fraction of area occupied by needle-like β-Al5FeSi IMCs for higher VL and TR values, 
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and lower βFe. On the other hand, with the decrease in VL and TR, as well as for higher 2 and 
βFe values, the wear resistance decreases and stabilizes as the wear volume and rate values 
reach constant values. 
 
Declaration of interests 
The authors declare that they have no known competing financial interests or personal 
relationships that could have appeared to influence the work reported in this paper. 
 
Acknowledgements 
The authors acknowledge the financial support provided by IFPA - Federal Institute of 
Education, Science and Technology of Pará, and CNPq - National Council for Scientific and 
Technological Development (Grant 302846/2017-4 and 308021/2018-5), FAPEMIG - Minas Gerais 
Research Foundation (Grant APQ-01301-15). CAPES−Coordenação de Aperfeiçoamento de Pessoal 
de Nível Superior-Brasil-Finance Code 001. 
 
 
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References 
[1] K. Das, W. Yin, The worldwide aluminum economy: The current state of the industry, J. 
Miner. Met. Mater. Soc. 59 (2007) 57−63. https://doi.org/10.1007/s11837-007-0142-0. 
[2] G. Gaustad, E. Olivetti, R. Kirchain, Improving aluminum recycling: A survey of sorting 
and impurity removal technologies. Resour. Conserv. Recy. 58 (2012) 79–87. 
https://doi.org/10.1016/j.resconrec.2011.10.010. 
[3] C. M. Dinnis, J. A. Taylor, A. K. Dahle, As-cast morphology of iron-intermetallics in Al-
Si foundry Alloys, Scr. Mater. 53 (2005) 955-958. 
https://doi.org/10.1016/j.scriptamat.2005.06.028. 
[4] R. Chen, Y. Shi, Q. Xu, B. Liu, Effect of cooling rate on solidification parameters and 
microstructure of Al-7Si-0.3Mg-0.15Fe alloy, Trans. Nonferrous Met. Soc. China 24 (2014) 
1645-1652. https://doi.org/10.1016/S1003-6326(14)63236-2. 
[5] S. Ji, W. Yang, F. Gao, D. Watson, Z. Fan, Effect of iron on the microstructure and 
mechanical property of Al–Mg–Si–Mn and Al–Mg–Si diecast Alloys, Mat. Sci. Eng. A 564 
(2013) 130-139. https://doi.org/10.1016/j.msea.2012.11.095. 
[6] B. Kim, S. Lee, S. Lee, H. Yasuda, Real-Time Radiographic Observation of Solidification 
Behavior of Al-Si-Cu Casting Alloys with the Variation of Iron Content, Mater. Trans. 53 
(2012) 374-379. https://doi.org/10.2320/matertrans.F-M2011834. 
[7] J. Rakhmonov, G. Timelli, F. Bonollo, Influence of grain refiner addition on the 
precipitation of Fe-rich phases in secondary AlSi7Cu3Mg alloys, Int. J. Metalcast. 11 (2017) 
294-304. https://doi.org/10.1007/s40962-016-0076-9. 
[8] S. Ji, W. Yang, F. Gao, D. Watson, Z. Fan, Effect of iron on the microstructure and 
mechanical property of Al-Mg-Si-Mn and Al-Mg-Si diecast Alloys, Mat. Sci. Eng. A 564 
(2013) 130–139. https://doi.org/10.1016/j.msea.2012.11.095. 
Jo
ur
na
l P
re
-p
ro
of
28 
 
[9] A. M. Samuel, H. W. Doty, S. Valtierra, F. H. Samuel, Beta Al5FeSi phase platelets-
porosity formation relationship in A319.2 type alloys, Int. J. Metalcast. 12 (2018) 55-70. 
https://doi.org/10.1007/s40962-017-0136-9. 
[10] A. M. Samuel, F. H. Samuel, H. W. Doty, Observations on the Formation of β-Al5FeSi 
phase in 319 type Al-Si alloys, J. Mater. Sci. 31 (1996) 5529-5539. 
https://doi.org/10.1007/BF01159327. 
[11] W. Khalifa, F. H. Samuel, J. E. Gruzleski, Iron Intermetallic Phases in the Al corner of 
the Al-Si-Fe system, Metall. Mater. Trans. A 34 (2003) 807-825. 
https://doi.org/10.1007/s11661-003-0116-y. 
[12] L. Ceschini, I. Boromei, A. Morri, S. Seifeddine, I. L. Svensson, Effect of Fe content and 
microstructural features on the tensile and fatigue properties of the Al-Si10-Cu2 alloy, Mater. 
Des. 36 (2012) 522-528. https://doi.org/10.1016/j.matdes.2011.11.047. 
[13] Z. Li, N. Limodin, A. Tandjaoui, P. Quaegebeur, P. Osmond, D. Balloy, Influence of Sr, 
Fe and Mn content and casting process on the microstructures and mechanical properties of 
AlSi7Cu3 alloy, Mat. Sci. Eng. A 689 (2017) 286-297. 
https://doi.org/10.1016/j.msea.2017.02.041 . 
[14] J. Malavazi, R. Baldan, A. A. Couto, Microstructure and mechanical behaviour of Al9Si 
alloy with different Fe contents, Mater. Sci. Technol. (2014) 1743-2847. 
https://doi.org/10.1179/1743284714Y.0000000659. 
[15] R. Taghiabadi, H.M. Ghasemi, S.G. Shabestari. Effect of iron-rich intermetallics on the 
sliding wear behavior of Al–Si alloys, Mat. Sci. Eng. A 490 (2008) 162–170. 
https://doi.org/10.1016/j.msea.2008.01.001. 
[16] R. Taghiabadi and H. M. Ghasemi. Dry sliding wear behaviour of hypoeutectic Al– 
Si alloys containing excess iron. Mater. Sci. Technol. 25 (2009) 1017-1022. 
https://doi.org/10.1179/174328408X302468. 
Jo
ur
na
l P
re
-p
ro
of
29 
 
[17] V. Abouei, H. Saghafian, S. G. Shabestari, M. Zarghami, Effect of Fe-rich intermetallics 
on the wear behavior of eutectic Al−Si piston alloy (LM13) Mater. Des. 31 (2010) 
3518−3524. https://doi.org/10.1016/j.matdes.2010.02.015 
[18] C. Lin, S. Wu, S. Lü, J. Zeng, P. An, Dry sliding wear behavior of rheocast hypereutectic 
Al−Si alloys with different Fe contents. Trans. Nonferrous Met. Soc. China 26 (2016) 
665−675. https://doi.org/10.1016/S1003-6326(16)64156-0. 
[19] H. Saghafian, S. G. Shabestari, S. Ghadami, M. H. Ghoncheh, Effects of Iron, 
Manganese, and Cooling Rate on Microstructure and Dry Sliding Wear Behavior of LM13 
Aluminum Alloy, Tribol. Trans. 60 (2017) 888-890. 
https://doi.org/10.1080/10402004.2016.1227513. 
[20] C. Bidmeshki, V. Abouei, H. Saghafian, S. G. Shabestari, M. T. Noghani, Effect of Mn 
addition on Fe-rich intermetallics morphology and dry sliding wear investigation of 
hypereutectic Al-17.5%Si alloys, J. Mater. Res. Technol 5 (2016) 250-258. 
https://doi.org/10.1016/j.jmrt.2015.11.008. 
[21] M. S. Kaiser, S. H. Sabbir, M. S. Kabir, M. R. Soummo, M. A. Nur, Study of Mechanical 
and Wear Behaviour of Hyper-Eutectic Al-Si Automotive Alloy Through Fe, Ni and Cr 
Addition, Mater. Res. 21 (2018) 1-9. https://doi.org/10.1590/1980-5373-mr-2017-1096. 
[22] X. Cao, J. Campbell, Morphology of β-Al5FeSi Phase in Al-Si Cast Alloys, Mater. Trans. 
47 (2006) 1303-1312. https://doi.org/10.2320/matertrans.47.1303. 
[23] C. B. Basak, N. H. Babu, Morphological changes and segregation of β-Al9Fe2Si2 phase: 
A perspective from better recyclability of cast Al-Si Alloys, Mater. Des. 108 (2016) 277-288. 
https://doi.org/10.1016/j.matdes.2016.06.096. 
[24] S. G. Shabestari, The effect of iron and manganese on the formation of intermetallic 
compounds in aluminum-silicon Alloys, Mat. Sci. Eng. A 383 (2004) 289-298. 
https://doi.org/10.1016/j.msea.2004.06.022. 
Jo
ur
na
l P
re
-p
ro
of
https://doi.org/10.1016/j.matdes.2010.02.015
30[25] M. Mahta, M. Emamy, X. Cao, J. Campbell, Overview of β-Al5FeSi phase in Al-Si 
Alloys, Mat. Sci. Res. Trends (2008) 251-271. 
[26] S. Pouladvand, R. Taghiabadi, F. Shahriyari, Investigation of the Tribological Properties 
of AlxSi-1.2Fe(Mn) (x = 5-13 wt.%) Alloys, J. Mater. Eng. Perform. 27 (2018) 3323-3334. 
https://doi.org/10.1007/s11665-018-3420-9. 
[27] J. E. Spinelli, I. L. Ferreira, A. Garcia. Evaluation of Heat Transfer Coefficients During 
Upward and Downward Transient Directional Solidification of Al–Si Alloys. Struct Multidisc 
Optim, 31 (2006) 241-248. https://doi.org/10.1007/s00158-005-0562-9. 
[28] C. R. Barbosa, J. O. M. Lima, G. M. H. Machado, H. A. M. Azevedo, F. S. Rocha, A. S. 
Barros, O. F. L. Rocha, Relationship Between Aluminum-Rich/Intermetallic Phases and 
Microhardness of a Horizontally Solidified AlSiMgFe Alloy, Mater. Res. 22 (2019) 1-12. 
https://doi.org/10.1590/1980-5373-mr-2018-0365. 
[29] A. Barros, C. Cruz, A. P. Silva, N. Cheung, A. Garcia, O. Rocha, A. Moreira, 
Horizontally Solidified Al-3 wt%Cu-(0.5 wt%Mg) Alloys: Tailoring Thermal Parameters, 
Microstructure, Microhardness, and Corrosion Behavior, Acta Metall. Sin. 32 (2019) 695-
709. https://doi.org/10.1007/s40195-018-0852-z. 
[30] I. A. Magno, F. A. Souza, M. O. Costa, J. M. Nascimento, A. P. Silva, T. S. Costa, O. L. 
Rocha, Interconnection between the solidification and precipitation hardening processes of an 
AlSiCu alloy, Mater. Sci. Technol. 35 (2019) 1743-2847. 
https://doi.org/10.1080/02670836.2019.1591028. 
[31] M. L. N. Melo, C. L. Penhalber, N. A. Pereira, C. L. Pelliciari, C. A. Santos, Numerical 
and experimental analysis of microstructure formation during stainless steels solidification, J 
Mater Sci 42 (2007) 2267–2275. https://doi.org/10.1007/s10853-006-0827-8. 
[32] K. S. Cruz, E. S. Meza, F. A. Fernandes, J. M. Quaresma, L. C. Casteletti, A. Garcia, 
Dendritic arm spacing affecting mechanical properties and wear behavior of Al-Sn and Al-Si 
Jo
ur
na
l P
re
-p
ro
of
https://doi.org/10.1007/s11665-018-3420-9
31 
 
alloys directionally solidified under unsteady-state conditions, Metall. Mater. Trans. A 
41(2010) 972–984. https://doi.org/10.1007/s11661-009-0161-2. 
[33] E. S. Freitas, J. E. Spinelli, L. C. Casteletti, A. Garcia, Microstructure– wear behavior 
correlation on a directionally solidified Al–In monotectic alloy, Tribol. Int. 66 (2013) 182–
186. https://doi.org/10.1016/j.triboint.2013.05.009. 
[34] E. S. Freitas, A. P. Silva, J. E. Spinelli, L. C. Casteletti, A. Garcia, Inter-relation of 
microstructural features and dry sliding wear behavior of monotectic Al–Bi and Al–Pb alloys, 
Tribol. Lett. 55 (2014) 111–120. https://doi.org/10.1007/s11249-014-0338-8. 
[35] T. A. Costa, M. Dias, E. S. Freitas, L. C. Casteletti, A. Garcia, The effect of 
microstructure length scale on dry sliding wear behaviour of monotectic Al-Bi-Sn alloys, J. 
Alloys Compd. 689 (2016) 767–776. https://doi.org/10.1016/j.jallcom.2016.08.051. 
[36] R. V. Reyes, V. E. Pinotti, C. R. Afonso, L. C. Casteletti, A. Garcia, J. E. Spinelli, 
Processing, As-Cast Microstructure and Wear Characteristics of a Monotectic Al-Bi-Cu 
Alloy, J. Mater. Eng. Perform. 28 (2019) 1201–1212. https://doi.org/10.1007/s11665-018-
3851-3. 
[37] T. M. Botelho, H. M. Azevedo, G. H. Machado, C. R. Barbosa, F. S. Rocha, T. A. Costa, 
O. L. Rocha, Effect of solidification process parameters on dry sliding wear behavior of 
AlNiBi alloy, Trans. Nonferrous Met. Soc. China 30 (2020) 582-594. 
https://doi.org/10.1016/S1003-6326(20)65237-2. 
[38] H. M. Azevedo, T. M. Botelho, C. R. Barbosa, A. P. Sousa, T. A. Costa, O. L. Rocha, 
Study of Dry Wear Behavior and Resistance in Samples of a Horizontally Solidified and 
T6/Heat‑ Treated Automotive AlSiMg Alloy, Tribol. Lett. 68 (2020). 
https://doi.org/10.1007/s11249-020-01302-z. 
[39] J. O. Lima, C. R. Barbosa, I. A. B. Magno, J. M. Nascimento, A. S. Barros, M. C. 
Oliveira, F. A. Souza, O. L. Rocha, Microstructural evolution during unsteady-state horizontal 
Jo
ur
na
l P
re
-p
ro
of
32 
 
solidification of Al-Si-Mg (356) alloy, Trans. Nonferrous Met. Soc. China 28 (2018) 1073-
1083. https://doi.org/10.1016/S1003-6326(18)64751-X. 
[40] D. Bouchard, J. S. Kirkaldy, Prediction of dendrite arm spacings in unsteady and steady-
state heat flow of unidirectionally solidified binary alloys, Metall. Mater. Trans. B, 28 (1997) 
651−663. https://doi.org/10.1007/s11663-997-0039-x. 
[41] R. Chen, Q. Xu, H. Guo, Z. Xia, Q. Wu, B. Liu, Correlation of solidification 
microstructure refining scale, Mg composition and heat treatment conditions with mechanical 
properties in Al-7Si-Mg cast aluminum alloys, Mater. Sci. Eng. A 685 (2017) 391–402. 
https://doi.org/10.1016/j.msea.2016.12.051. 
[42] L. A. Narayanan, F. H. Samuel, J. E. Gruzleski, Crystallization behavior of iron-
containing intermetallic compounds in 319 aluminum-alloy, Metall. Mater. Trans. A 25 
(1994) 1761–1773. https://doi.org/10.1007/BF02668540. 
[43] R. C. Cozza, D. K. Tanaka, R. M. Souza, Friction coefficient and abrasive wear modes in 
ball-cratering tests conducted at constant normal force and constant pressure - preliminary 
results, Wear, 267 (2009) 61–70. https://doi.org/10.1016/j.wear.2009.01.055. 
[44] Y. H. Cheng, T. Browne, B. Heckerman, Mechanical and tribological properties of CrN 
coatings deposited by large area filtered cathodic arc, Wear 271 (2011) 775–782. 
https://doi.org/10.1016/j.wear.2011.03.011. 
[45] R. V. Camerini, R. B. Souza, F. Carli, A. S. Pereira, N. M. Balzaretti, Ball cratering test 
on ductile materials, Wear, 271 (2011) 770–774. https://doi.org/10.1016/j.wear.2011.03.013. 
[46] B. P. Reis, M. M.Lopes, A. Garcia, C. A. Santos, The correlation of microstructure 
features, dry sliding wear behavior, hardness and tensile properties of Al-2wt% Mg-Zn alloys. 
J. Alloys Compd 764 (2018) 267-278. https://doi.org/10.1016/j.jallcom.2018.06.075. 
[47] C. Ache, M. Lopes, B. Reis, A. Garcia, C. Santos. Dendritic Spacing/Columnar Grain 
Diameter of Al–2Mg–Zn Alloys Affecting Hardness, Tensile Properties, and Dry Sliding 
Jo
ur
na
l P
re
-p
ro
of
https://doi.org/10.1016/j.wear.2011.03.013
https://doi.org/10.1016/j.jallcom.2018.06.075
33 
 
Wear in the As Cast/Heat Treated Conditions. Adv Eng Mater (2020). 
https://doi.org/10.1002/adem.201901145. 
[48] S. Seifeddine, S. Johansson, I. L. Svensson. The influence of cooling rate and manganese 
content on the β-Al5FeSi phase formation and mechanical properties of Al–Si-based alloys. 
Materials Science and Engineering: A. (2008) 490(1-2), 385-390. 
https://doi.org/10.1016/j.msea.2008.01.056. 
[49] İ. Şimşek, D. Özyürek, Investigation of the effects of Mg amount on microstructure and 
wear behavior of Al-Si-Mg alloys, Eng. Sci. Technol. an Int. J. 22 (2019) 370–375. 
https://doi.org/10.1016/j.jestch.2018.08.016 
[50] I. Sağlam, D. Özyürek, K. Çetinkaya, Effect of ageing treatment on wear properties and 
electrical conductivity of Cu-Cr-Zr alloy, Bull. Mater. Sci. 34 (2011) 1465–1470. 
https://doi.org/10.1007/s12034-011-0344-5 
[51] J. X. Dong, P. A. Karnezis, G. Durrant, B. Cantor, The effect of Sr and Fe additions on 
the microstructure and mechanical properties of a direct squeeze cast Al-7Si-0.3 Mg alloy, 
Metall. Mater. Trans. A 30 (1999) 1341–1356. https://doi.org/10.1007/s11661-999-0283-6 
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https://doi.org/10.1002/adem.201901145
https://doi.org/10.1016/j.msea.2008.01.056