Investigation of heat treatment effect on physical properties of cu-al-ni-nb quaternary shape memory alloys

One of the important treatments that generally are using in industry and other fields of studies is heat treatment. Aging is a type of heat treatment that can be accomplished either with time dependence or temperature dependence. In this study, quaternary Cu-Al-Ni-Nb shape memory alloy was produced and for 1, 2, 3, 6, 12, and 24 hours it was kept at 1073K. The as-quenched and heat-treated alloys were investigated. The alloys were showed high-temperature shape memory characteristics and the aging increased its martensitic phase transformation temperatures. Additionally, the alloy lost its shape memory properties for 24 hours aged at 1073K. Furthermore, other thermodynamics parameters were affected through an increasing time of aging. It was found that 3 hours aged sample has minimum enthalpy change for martensite phase transformation. On the other hand, map analysis of the composition illustrated that copper and niobium did not dissolve to each other, nickel was homogeneously distributed, and a low concentration of aluminum dissolved in the Nb-rich phase compared to the matrix.