Cavitation erosion-corrosion characteristics of laser surface modified NiTi shape memory alloy

In the presented work, the cavitation erosion-corrosion behavior of a nearly equiatomic NiTi alloy subjected to hot rolled, laser surface melting and laser gas nitriding (LGN) was investigated. Results show that the tested samples are very resistant to erosion damage. Secondary phases and inclusions are harmful to the erosion resistance of the alloy, and the interface between particles and matrix initiates the crack formation and material removal. A clean, compact microstructure with ultrafine grain, high work hardening ability and fatigue strength contributes to the improved resistance to cavitation erosion-corrosion of the laser surface melted NiTi alloy. The high resistance to erosion of the LGN sample is attributed to the high hardness of the TiN surface layer. (C) 2002 Elsevier Science B.V. All rights reserved.