The effect of post-quench aging on the stability of Cu-Zn-Al-Ni shape memory alloys

Abstract
The effect of Ni addition to Cu-Zn-Al alloys on the stability of the martensite after step-quench with different aging times in the ( -phase has been studied byeleetrieal resistivity measurements. When more than 2at.% of Ni added, the martensites still remain stabilized partl y on heating until the decomposition reaction occurs even after aged for 30 min in the -phase. while the other part of the martensites revert to the-phase normally without stabilization. With increasing aging time in the -phase, the ratio of the stabilized martensite to the non stabilized martensite decreases, and finally the martensites become non stabilized state by prolonge aging. The coexistence of the stabilized and non stabilized martensites indicates that non-chemical mechanisms such as vacancy pinning are responsibie for the stabitization of the martensite by quenching.