Shape Memory Behavior and Tribological Analysis of Heat-Treated NiTiFe Alloy

The objective of this work is to study the effects of Fe additions on the phase evolution, microstructure, and mechanical properties of heat-treated Ni(50-X)Ti50FeX shape memory alloys. The NiTiFe specimens were prepared by mechanical alloying, compaction, sintering, and heat treatment processes. The microstructural and phase analysis of the sample shows the NiTiFe phase along with Ti-rich and Ni-rich phases. Better mechanical properties were observed in 4 at.% Fe samples owing to the presence of secondary intermetallic phases such as Ti2Ni, Ni3Ti, Fe3Ti, and Ni4Ti3 compared to other samples. The 10 at.% Fe samples containing a higher percentage of NiTi(B19') and FeTi phases showed better shape memory behavior while showing a higher coefficient of friction as compared to other samples. Wear tests were done to determine the wear mechanisms prevalent during the tests. It was found that the adhesive and the abrasive wear were the most common mechanisms that contributed to the wear behavior of the sample.