A study on lattice parameters of martensite in Ti50.5-xNi49.5Zrx shape memory alloys

摘要

Ti50.5-xNi49.5Zrx (x=5 similar to 20 at.%) shape memory alloys exhibit the characteristics of B2 <----> B19' martensitic transformation and their transformation temperatures increase linearly with increasing Zr content. The lattice parameters of B19' martensite in these alloys are determined by XRD, SADP of TEM and the Rietveld method. Experimental results show that all of the lattice parameters a and c, monoclinic angle beta and unit cell volume V increase, but lattice parameter b decreases with increasing Zr content in Ti50.5-xNi49.5Zrx alloys. The results of the Rietveld method indicate that the martensite of Ti50.5-xNi49.5Zrx with x less than or equal to 10 at. % has a structure similar to that of Ti50Ni50, but that of Ti50.5-xNi49.5Zrx with x greater than or equal to 15 at.% may change in structure. (C) 1998 Elsevier Science S.A. [References: 24]