Abstract:Phase equilibria in Ti-Ni-Pt ternary system have been experimentally determined through diffusion triple technique combined with alloy samples approach. Assisted with electron probe microanalysis (EPMA) and X-ray diffraction (XRD) techniques, isothermal sections at 1073 and 1173 K of this system were constructed and existence of ternary phase Ti2(Ni,Pt)3 was confirmed. In addition, binary compounds Ti3Pt5 and TiPt3- were found to be stable at 1073 and 1173 K, and remarkable ternary solubility in some binary compounds was detected, e.g., solubility of Pt in TiNi can be up to about 36% (molar fraction) at 1073 K and 40% (molar fraction) at 1173 K. Furthermore, a ternary invariant transition reaction TiNi3+Ti3Pt5→Ti2(Ni,Pt)3+TiPt3+ at a temperature between 1073 and 1173 K was deduced.

Key words: Ti-Ni-Pt ternary system; phase equilibrium; diffusion triple; solubility