Paper Title
Effect Of Cu Addition On Microstructure And Transformation Temperatures Of Ti50ni25pd25 High Temperature Shape Memory Alloys

Abstract
High temperature shape memory alloys Ti50Ni25Pd25 and Ti50Ni20Pd25Cu5 were developed and characterized for microstructural analysis and transformation temperatures. Both ternary and quaternary alloys were consisted of single martensite phase having second phase precipitates; Ti2Ni (Pd, Cu) randomly distributed along the grain boundaries. The average grain size 13µm of the ternary alloy Ti50Ni25Pd25 was increased to 16µm by replacing Ni with 5 at%Cu. Martensite start temperatures of ternary Ti50Ni25Pd25 alloy was increased by 12.5 °C by substitution of Ni with 5 at% Cu. At the same time, transformation heat absorbed and released during forward and reverse martensitic transformation was also increased. The overall results suggested that by addition of 5 at% Cu in place of Ni in Ti50Ni25Pd25 alloy, the microstructure remained almost same, however the transformation temperatures was increased significantly. Index Terms— Phase Transformation Temperature; High Temperature Shape memory alloy; Transformation Heat; Second Phase Precipitate.