Elastic Moduli and Mechanical Properties of Mo₅SiB₂ Single Crystals in the Mo-Si-B System

Abstract

With outstanding high-temperature properties, the intermetallic Mo5SiB2 alloy is regarded as an extremely competitive ultra-temperature structural material. The maximum Young’s modulus of 398.0 GPa for single Mo5SiB2 crystals was found to be at the vertex of the [010] direction, while the minimum value of 264.0 GPa was found in the [001] direction. For hardness, the maximum value was 451.7 HV after compression at 1200 °C in the radial direction, while the maximum hardness was 437.2 HV at 1300 °C in the axial direction of {111}, showing obvious anisotropy. Under compression, the flow stresses rapidly increased and then decreased with the increase in strain, corresponding to the two different stages of work hardening and softening. An EBSD test showed that the grain orientation remained the same at different rates, but the texture was different. After high-temperature compression, the crystal underwent plastic deformation, dislocations slipped along the slip plane, and the grain rotated, so the grain texture changed from {111} to {001}.

Keywords

• single crystals
• Mo₅SiB₂
• mechanical properties
• physical moduli