Fracture strength, elastic modulus and Poisson's ratio of polycrystalline 3C thin-film silicon carbide found by microsample tensile testing

Abstract

This paper reports the measurement of elastic modulus, fracture strength, and Poisson's ratio of thin-film 3C polycrystalline silicon carbide determined by microsample tensile tests. The tensile specimens had a gage width of 600 μm, gage length of 4 mm, and gage thicknesses of 20–40 μm. A custom-built microsample tensile testing machine was used to conduct the tests and strain was measured with a laser-based direct strain measurement system. Twenty-three tests were completed on two sets of material with two different grain textures. Results of the microsample tensile tests show an average elastic modulus of 428 GPa, Poisson's ratio of 0.24 and fracture strength of 0.49 GPa for batch 1. Batch 2, a material with a different texture, resulted in an average elastic modulus of 448 GPa, Poisson's ratio of 0.17 and fracture strength of 0.81 GPa. In addition to differences in average values, variations were also seen in the Weibull characteristics of the two differently textured materials.