A researcher measures Vickers hardness (HV) and electrical resistivity ρ for four copper-based samples. Pure copper has HV=70 and ρ=1.7×10−8Ωm.
Sample W: HV=70, ρ=1.7×10−8Ωm
Sample X: HV=150, ρ=1.9×10−8Ωm
Sample Y: HV=155, ρ=4.5×10−8Ωm
Sample Z: HV=70, ρ=4.6×10−8Ωm
Which sample is most likely an interstitial alloy of copper?
a) Sample X
b) Sample Y
c) Sample Z
d) Sample W