Martensitic transformation behavior of Ti-Ni-Ag alloys

Abstract

Microstructures and martensitic transformation behavior of Ti-Ni-Ag alloys prepared by arc melting were investigated by means of scanning electron microscopy (SEM), electron probe micro analysis (EPMA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and thermal cycling tests under constant load. Ti-Ni-Ag alloys consisted of Ti-Ni-Ag matrices, Ti2Ni and TiAg phases. Ti-Ni-Ag matrices contained 0.27-0.52 at.% of solute Ag atoms depending on alloy compositions. The B2-B19' transformation occurred in Ti-50.1Ni-0.7Ag, Ti-49.2Ni-0.9Ag, Ti-49.2Ni-0.6Ag and Ti-49.0Ni-0.7Ag alloys, while the B2-R-B19' transformation did in Ti-47.5Ni-1.3Ag and Ti-44.4Ni-1.1Ag alloys. Thermo-mechanical treatment separated the B2-R from the R-B19' transformation clearly and improved shape recovery by increasing the critical stress for slip deformation in a Ti-50.0Ni-0.7Ag alloy. (C) 2013 Elsevier Ltd. All rights reserved.