Effects of methane plasma ion implantation on the microstructure and wear resistance of NiTi shape memory alloys

This paper reports the surface characterization, microhardness and fretting wear behavior of methane-plasma-modified NiTi as well as those control samples. Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy were used for surface characterization. It is found that the hardness of methane-treated samples is highly improved with surface modification due to the contribution from titanium oxides, titanium carbide and organic titanium compounds. A new modified Archard's equation is used to describe the relationship between pseudoelasticity, hardness and wear resistance. This study provides an understanding of the interplay between surface microstructure and mechanical properties of methane-treated NiTi.