Deformation behavior of Mo5Si3 single crystal at high temperatures

Compressive deformation behavior of D8m-type Mo5Si3 single crystals was investigated at temperatures between 1473 and 1723 K in an argon atmosphere. Four compression axes, namely [001], near-[111], near-[101] and [100] were chosen. Plasticity occurred at and above 1573 K, whereas at 1473 K the crystals failed by brittle fracture before yielding. After high-temperature yielding, all crystals except the [001] crystal exhibited a large yield drop, followed by an apparent steady state flow. Slip traces of {110} and other relatively low index planes were observed on crystal surfaces. Dislocations were characterized on (001) slip plane by TEM, and 〈110〉(001) slip was identified. Considering the constant-stress flow behavior as a steady-state creep process, it was estimated that a stress component is about 6 and an apparent activation energy of deformation is approximately 490 kJ mol−1.