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

Abstract

In this paper we report on the characterization of predominantly single phase, fully dense Ti2InC (Ti1.96InC1.15), Hf2InC (Hf1.94InC1.26) and (Ti,Hf)2InC ((Ti0.47,Hf0.56)2InC1.26) 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 TiCx. © 2002 Elsevier Science B.V. All rights reserved.