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Resolução Callister Capítulo 3 Engenharia dos Materiais

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which results are tabulated below: 
 
 Peak Index 2θ dhkl(nm) a (nm) 
 200 36.6 0.2455 0.4910 
 220 52.6 0.1740 0.4921 
 311 62.5 0.1486 0.4929 
 222 65.5 0.1425 0.4936 
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 3-79 
 3.64 The first four diffraction peaks that will occur for BCC consistent with h + k + l being even are (110), 
(200), (211), and (220). 
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 3-80 
 3.65 (a) Since W has a BCC crystal structure, only those peaks for which h + k + l are even will appear. 
Therefore, the first peak results by diffraction from (110) planes. 
 (b) For each peak, in order to calculate the interplanar spacing we must employ Equation 3.13. For the 
first peak which occurs at 40.2° 
 
 
d110 =
nλ
2 sin θ
= (1)(0.1542 nm)
(2) sin 40.2°
2
⎛ 
⎝ 
⎜ 
⎞ 
⎠ 
⎟ 
 = 0.2244 nm 
 
 (c) Employment of Equations 3.14 and 3.3 is necessary for the computation of R for W as 
 
 
R =
a 3
4
=
(dhkl)( 3) (h)2 + (k)2 + (l)2
4
 
 
 
=
(0.2244 nm)( 3) (1)2 + (1)2 + (0)2
4
 
 
= 0.1374 nm 
 
Similar computations are made for the other peaks which results are tabulated below: 
 
 Peak Index 2θ dhkl(nm) R (nm) 
 200 58.4 0.1580 0.1369 
 211 73.3 0.1292 0.1370 
 220 87.0 0.1120 0.1371 
 310 100.7 0.1001 0.1371 
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 3-81 
 Noncrystalline Solids 
 
 3.66 A material in which atomic bonding is predominantly ionic in nature is less likely to form a 
noncrystalline solid upon solidification than a covalent material because covalent bonds are directional whereas 
ionic bonds are nondirectional; it is more difficult for the atoms in a covalent material to assume positions giving 
rise to an ordered structure. 
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