Isothermal section at 927 ℃ of Cr-Ni-Ti system
(State Key Laboratory of Powder Metallurgy, Central South University,
Changsha 410083, China)
Changsha 410083, China)
Abstract: The isothermal section at 927 ℃ of the Cr-Ni-Ti system was established using a high-efficiency diffusion couple approach, supplemented with eight equilibrated alloys. The alloy compositions were selected on the basis of the experimental results from the diffusion couple. Both the diffusion couple specimens and the alloys were examined by means of optical microscopy, scanning electron microscopy, and electron probe microanalysis. No ternary compound is found at 927 ℃. The following five three-phase equilibria are well determined: TiNi3+(Cr)+(Ni), TiNi3+(Cr)+TiNi, TiNi+(Cr)+Cr2Ti, Ti2Ni+Cr2Ti+TiNi and Ti2Ni+Cr2Ti+(Ti). The solubilities of Cr in NiTi2, NiTi, and Ni3Ti are determined to be 7.5%, 14.5% and 11.4% (molar percent), respectively. α-Cr2Ti and β-Cr2Ti dissolve about 9.2% and 13.9% Ni (molar percent), respectively.
Key words: Cr-Ni-Ti ternary system; phase diagram; diffusion; EPMA