Five experimental interstitial alloys were prepared by adding different small atoms…
CHEMISTRY · Multi-part · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
Five experimental interstitial alloys were prepared by adding different small atoms to copper metal. Relevant data for each alloy are shown in the table below.
Alloy
Small atom added
Atomic radius of added atom (pm)
Mole fraction of added atoms
A
B
87
0.02
B
C
77
0.02
C
N
65
0.02
D
B
87
0.05
E
N
65
0.05
Assume that the copper lattice retains its face-centered cubic arrangement in all cases and that the added atoms occupy interstitial sites.
(a) Rank the five alloys (A–E) in order of expected hardness, from hardest to softest. Clearly indicate any ties if you believe two alloys should have similar hardness.
(b) Provide two separate, well-reasoned justifications for the order you proposed in part (a). One justification should focus on atomic size considerations, and the other should focus on concentration of interstitial atoms.
(c) Predict which alloy, if any, is most likely to retain ductility comparable to that of pure copper. Support your prediction with reference to lattice rigidity.