Fabrication and electrical and thermal properties of Ti2InC, Hf2InC and (Ti,Hf)2InC

In this paper we report on the characterization of predominantly single phase, fully dense Ti₂InC (Ti_1.96InC_1.15), Hf₂InC (Hf_1.94InC_1.26) and (Ti,Hf)₂InC ((Ti_0.47,Hf_0.56)₂InC_1.26) samples produced by reactive hot isostatic pressing of the elemental powders. The a and c lattice parameters in nm, were, respectively: 0.3134; 1.4077 for Ti₂InC; 0.322, 1.443 for (Ti,Hf)₂InC; and 0.331 and 1.472 for Hf₂InC. The heat capacities, thermal expansion coefficients, thermal and electrical conductivities were measured as a function of temperature. These ternaries are good electrical conductors with a resistivity that increases linearly with increasing temperatures. At 0.28 μΩ m, the room temperature resistivity of (Ti,Hf)₂InC is higher than the end members (0.2 μΩ m), indicating a solid solution scattering effect. In the 300 to 1273 K temperature range the thermal expansion coefficients are: 7.6×10^?6 K^?1 for Hf₂InC, 9.5×10^?6 K^?1 for Ti₂InC, and 8.6×10^?6 K^?1 for (Ti,Hf)₂InC. They are all good conductors of heat (20 to 26 W/m K) with the electronic component of conductivity dominating at all temperatures. Extended exposure of Ti₂InC to vacuum (10^?4 atm) at 800 °C, results in the selective sublimation of In, and the conversion of Ti₂InC to TiC_x.