Characterization and thermodynamic study of nanostructured Cu‐26Zn‐4Al (wt.%) shape memory alloy through mechanical alloying

Abstract

AbstractIn the current study, nanostructured Cu−Zn−Al ternary alloy was synthesized via mechanical alloying. The structural evolutions were also measured using x‐ray diffraction and scanning electron microscope. The results showed an increase in lattice strain while the crystallite size decreased. Afterwards, thermodynamic analysis was carried out on Cu−Zn, Cu−Al and Zn−Al binary systems through Miedema's semi‐empirical model. It was found that in all binary systems, there is a driving force for solid solution formation over all compositions due to its negative Gibbs free energy changes in those compositions, whilst, this value is positive for the formation of amorphous phase over some compositions which can be attributed to the absence of driving force. Finally, the extended version of Miedema's semi‐empirical model was used and discussed in detail to determine the thermodynamic desirability of solid solution and amorphous phase formation for Cu−Zn−Al ternary system. It was concluded that in this ternary system, the minimum thermodynamic driving force for solid solution formation occurred for those compositions which were located in the corners of ternary diagram.