Influence of Zirconium Percentage on Microhardness and Corrosion Resistance of Ti50 Ni50-xZrx Shape Memory Alloys

To obtain high temperature shape memory alloys of the lower cost Ni-Ti-X system, elements such as Hf and Zr are introduced to modify the thermal and mechanical properties of these alloys. This work studied the production and characterization of Ti50 Ni50-x Zrx alloys (x = 0, 5, 10 at.%) with the aim of improving their thermal, mechanical and corrosion resistance properties. In the resulting alloys, transformation of phase B2 into phase B19' occurred in a single stage. The addition of zirconium led to an increase of transformation temperatures, as well as the appearance of second phase particles in the grain boundaries of the matrix. The increase in zirconium percentage favored the increase of corrosion resistance from 520.23KΩ to 1007.30KΩ and of microhardness from 346HV to 543HV for the N0 and N10 alloys, respectively.