Study on the corrosion behavior of NiTi shape memory alloys fabricated by electron beam melting

Abstract

Abstract The poor processability of NiTi shape memory alloy with superior resistance to corrosion and wear is an important reason for hindering its extensive application. In this work, NiTi alloy was fabricated by electron beam melting (EBM) using different fabrication parameters including changed speed function and focus offset. Furthermore, the influence of these parameters on the corrosion behavior of EBM NiTi alloys was investigated. It was found that the variation in fabrication parameters caused different defect types and defect number, thus affecting the corrosion resistance of NiTi alloys. The alloy with a large number of cracks displayed the lowest corrosion resistance, while a superior corrosion resistance equivalent to the wrought alloy was observed when a few small pores were uniformly distributed in the alloys. Electrochemical results indicated that the EBM NiTi alloy with optimized fabrication parameters presented a low carrier density indicating good protective ability of the passive films.