Investigation on Mechanical Properties of 6H-SiC Crystal

In this work, the mechanical properties, such as Vickers microhardnessHv, fracture toughnessKc, yield strengthσvand brittleness indexBi, of oriented 6H-SiC crystal are systematically evaluated using a microindentation technique under 0.1-2 kg applied load. It is found theHvis decreased as the applied load is increased which is mainly attributed to the effect of indenter penetration. TheHvvalue can be effectively presumed by Kicks law and the Meyers indexnis determined to be 1.73. However, theKcvalue is measured nearly a constant (~0.148 MPa.m1/2) which reveals the toughness of 6H-SiC(0001)crystal is much weaker than those of Si(100)and GaAs(100)crystals. The variation ofσvto the load is similar to that ofHv. The brittleness indexBialso exhibits deceasing tendency as the applied load is added.