Elastic stiffnesses of copper-tin and copper-aluminum alloy single crystals

Abstract

The elastic stiffnesses of a series of Cu–Sn and Cu–Al alloys have been measured. Both C=c₄₄ and C=(1/2)(c₁₁−c₁₂) decrease as Sn concentration increases. However for the Cu–Al alloys, C increases while C′ decreases. The results have been compared to those predicted by the theory of Fuchs. For the Cu–Al alloy the agreement is fair, while for the Cu–Sn alloy it is poor. Curvature in the plots of C and C′ vs composition is found mostly to be a consequence of the lattice parameter effect on the elastic stiffnesses. The effect due to alloying alone deviates only slightly from linearity for solute concentrations less than 8 at.%.