In order to clarify the effect of C/Ti atom ratios(χ) on the deformation behavior of TiCχ at high temperature, singlecrystals having a wide range of χ, from 0.56 to 0.96, were deformed by compression test in a temperature range of 1183~2273Kand in a strain rate range of 1.9×10−4~5.9×10−3s−1. Before testing, TiCχ single crystals were grown by the FZ method ina He atmosphere of 0.3MPa. The concentrations of combined carbon were determined by chemical analysis and the latticeparameters by the X-ray powder diffraction technique. It was found that the high temperature deformation behavior observedis the χ-less dependent type, including the work softening phenomenon, the critical resolved shear stress, the transitiontemperature where the deformation mechanism changes, the stress exponent of strain rate and activation energy for deformation.The shape of stress-strain curves of TiC0.96, TiC0.85 and TiC0.56 is seen to be less dependent on χ, the work hardening rate afterthe softening is slightly higher in TiC0.96 than in TiC0.85 and TiC0.56. As χ decreases the work softening becomes less evidentand the transition temperature where the work softening disappears, shifts to a lower temperature. The τc decreasesmonotonously with decreasing χ in a range of χ from 0.86 to 0.96. The transition temperature where the deformationmechanism changes shifts to a lower temperature as χ decreases. The activation energy for deformation in the low temperatureregion also decreased monotonously as χ decreased. The deformation in this temperature region is thought to be governed bythe Peierls mechanism.

• Shin, Soon-Gi(Department of Advanced Materials Engineering, College of Samcheok, Kangwon National University)