Shape-memory effect in a Cu-Al-Ni alloy

Abstract

In this study, the microstructure and mechanical property relationship of Cu-13.98Al-2.94Ni (wt.pct.) alloy that exhibits shape-memory effect is investigated. A brief review of thermoelasticity, pseudoelasticity, and memory effects are presented together with the complementary relationship of shape-memory effect and pseudoelastie effect. Then the mechanical behaviour, mechanisms, and some applications of shape-memory alloys are given. After these, the Cu-Al-Ni alloy system is explained in detail. In the experimental work, the Cu-Al-Ni alloy system is produced and the mechanical properties are measured with bending and hardness testing. The microstructures are examined using the techniques of optical microscopy. For the present alloy, room temperature is between Ms and As· Therefore, it is either in the parent phase or in the martensitic state at room temperature; The shape-memory effect occured on deformation in both states. Deformation caused the formation or reorientation of the martensite plates dependingon the initial position of the alloy. When the specimen was heated, the martensite plates formed in both states disappeared and the specimen reverted back to its original shape.