Experimental investigation and thermodynamic calculation of Ti-Hf-Mn system.

The phase relationship of Ti-Hf-Mn system was studied by diffusion triple and equilibrated alloy methods. The isothermal sections at 1373, 1273 and 1173 K for this system were constructed by means of electron probe microanalysis (EPMA) and X-ray diffraction (XRD) for the first time. No ternary phase was found in the system at all these temperatures. Six, seven and seven three-phase equilibria regions have been determined at 1373, 1273 and 1174 K, respectively. In this ternary system, the intermetallic compounds TiMn 2 , HfMn 2 and HfMn exhibit wide solid solution range at those three temperatures. In particular, the solution range of Ti in HfMn phase decreases with the increase of temperature, from 30.5 at% at 1173 K to 26.5 at% at 1373 K. Based on all available experimental data, the Ti-Hf-Mn system was evaluated using the CALPHAD method. The calculation results are in excellent agreement with the experimental data. Image 1 • 1373, 1273 and 1173 K isothermal sections of Ti-Hf-Mn system were first established over the whole composition range. • The solid solubility of Ti in HfMn phase was up to 20.6 at. % at 1373 K. • The continuous solid solution of (Ti,Hf)Mn 2 phase was confirmed at three different temperatures. • The thermodynamics data were built and optimized for this system. [ABSTRACT FROM AUTHOR]