Mo-TiC複合材料の室温∼2270 Kにおける強度特性とその解析

抄録

(Ti_0.74Mo_0.26)C_0.96 (δ phase) and Mo-1.5Ti-12C (β phase) solid solutions, and hypo Mo-10TiC and hyper Mo-40TiC eutectic composites were prepared and deformed by compression in a temperature range from 285 to 2270 K and in a strain rate range from 5×10⁻⁵ to 7×10⁻³ s⁻¹. The strengths of Mo-23.5TiC lamellar eutectic composite reported earlier and those of the above hypo and hyper eutectic composites were analysed from the strengths of component δ and β phases.
It is found that the extremely high strength of the lamellar eutectic composite is due primarily to solution hardening of TiC by Mo, and that the δ phase undergoes an appreciable plastic deformation at 1470 K and above even at 0.2% plastic strain of the composite. The yield strength of the three kinds of composites up to 1470 K is quantitatively explained by the ‘rule of mixture’, where internal stresses introduced by plastic deformation are taken into account. The magnitude of internal stresses in the component phases is evaluated on the assumption that both the components are equally strained. Above 1470 K, however, the evaluated yield strength is considerably larger than the measured strength, indicating that the effects of recovery of the internal stress and phase-boundary sliding become significant at such high temperatures.