Influences of Ni/Ti ratio on NiTiTa alloys
Influences of Ni/Ti ratio on NiTiTa alloys
S. Cai, J.E. Schaffer
Fort Wayne Metals Research Products Corp, Fort Wayne, IN 46809
Abstract: Our previous effort of making high strength, high radiopaque super-elastic NiTiTa alloys failed due to their high phase transformation temperature and limited ductility. When Ta is in solution, it largely increases phase transformation temperature. Above its’ solubility level, it forms brittle (TaTi)2Ni particles that reduces the material’s ductility. In this study, we focused on the effect of Ni/Ti ratio on NiTiTa alloys, especially on phase transformation temperatures and Ta solubility. Alloys with different Ni/Ti ratios and Ta content are melted and processed down to Ø0.50 mm wires. Phase transformation temperatures are measured by DSC testing. Microstructures and phase constitutions are investigated by SEM and Synchrotron X-ray diffraction. Tensile and bending fatigue mechanical properties after various heat treatments are evaluated. This study provides a useful data set to researchers in both academia and industry.