Effects of Plastic Deformation and Temperature on Microstructural and Mechanical Properties of a Cu Al Ni Shape Memory Alloy

Abstract

In Cu 12.88% wt.Al4 %wt. Ni shape memory alloy the influence of plastic deformation and thermal treatments on the microstructures and hardness were studied by optical microscopy, scanning electron microscopy (SEM), Vickers Hardness. The plastic deformation on the austenite (b) was studied at temperatures T>Md when transformation can occur with no stress or strain induced condition. Lattice defects were introduced into stable austenite of a Cu Al Ni alloy by a hot rolling, in one pass, and subsequent quenching after leaving the rolling cylinders. From microstructural observations it has been seen that two b₁^’(18R) and g₁^’(2H) martensite phases coexists at different fractions in the undeformed and deformed states. Plastic deformation causes change in the relative amounts of b₁^’and g₁^’ martensites with a new morphology. The finest martensite structure has been obtained by thermo-mechanical treatment. The hardness test highlights the influence of treatments tightly correlated with the structures obtained.