Microstructure and martensitic transformation of Ti49Ni51 − xHfx high temperature shape memory alloys

Abstract In present work, the microstructure and martensitic transformation of Ti 49 Ni 51 −  x Hf x ( x  = 3–15) alloys were studied. The microstructure of Ti 49 Ni 51  −  x Hf x alloys consists of B19′ martensite and (Ti,Hf) 2 Ni phase at room temperature. The martensitic transformation behavior is characterized by a single-stage transformation. With increasing Hf content, the transformation temperature increases from 75 to 279 °C resulting from the reduced valence electron concentration, indicating that the replacement of Hf for Ni is effective in increasing the transformation temperatures. The results suggest that the Ti 49 Ni 51 −  x Hf x shape memory alloy is one of potential candidates for high temperature applications.

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