Effect of Existing Twin Boundaries in Martensite on the Rubber-Like Behavior and Ageing Effect in Au-Cd Alloys

Abstract

The effect of existing twin(or intervariant) boundaries on both the rubber-like behavior and the ageing effect(Af temperature increase) was studied by using γ 2 ' (orthorhombic) and ζ 2 '(trigonal) martensites in Au-Cd alloys. A typical rubber-like behavior was observed even in a single-variant specimen of γ 2 ' martensite, which proves that the presence of twin boundaries is not the necessary condition for the rubber-like behavior. Thus, the previously proposed mechanism for pinning of boundaries was denied. However, the observed Af temperature increase in the ζ 2 ' martensite was more pronounced in the specimen with twin boundaries(multivariant state) rather than that without twin boundaries(single-variant state). Thus, it was found that the presence of twin boundaries affects the development of ageing effect though it is not the direct origin for the phenomenon.