Anisotropy of the Knoop Hardness in Silicon Nitride Single Crystals and Their Slip System at Room Temperature

Abstract

Knoop hardness in α-Si₃N₄ on the surfaces of (1100), (1120) and (0001) was investigated. Hardness values had isotropic character on all surfaces. Effective resolved shear stress (ERSS) was calculated assuming the slip systems of (0001) ‹1120›, {1100} ‹1120›, {1100} ‹0001›, {1101} ‹1120› and {2201} ‹1120› to be activated. The ERSS curve of the {1101} ‹1120› slip system explains Knoop hardness better than those of other slip systems. This fact supports {1101} ‹1120› to be the primary slip system in α-Si₃N₄ at room temperature.