The Effect of Heat-Treatment and Alloying of Ni-Ti Alloy with Copper on Improving its Fatigue Life

Abstract

Ni–Ti alloys have achieved great importance in industry, mainly for their innovative use in practical medical applications . A major reason for that is their fatigue lives. In this research, fatigue life of different Ni–Ti alloys has been investigated for different compositions of Ni–Ti alloy samples and different percentages of copper additions. Three major compositions were investigated under different fatigue loadings. The first group of samples had a composition of Ni47.8Ti42.2, and the remaining 10% was copper . A second group of samples had a composition of Ni52.8Ti42.2 and 5% of copper , and a third group pf samples had a composition of Ni47.8Ti47.2 and 5% of copper . These samples were prepared by casting. Comparison between fatigue lives of the prepared samples and the Ni52.8Ti47.2 sample was made, once without heat treatment of samples and once with heat treatment to find the best alloy composition with the best fatigue life . It was found that adding copper would improve the fatigue life of NiTi such that Ni has significantly higher percentages than Ti. Moreover, heat treating the NiTiCu alloy would improve its fatigue life by almost 10%.