Plastic deformation of silicon nitride single crystals

The plastic deformation behavior of silicon nitride single crystals was tested by two different methods: high temperature compression and room temperature hardness anisotropy. Macroscopic plastic deformation was observed above 1820 °C at a strain rate of 2 × 10−5 s−1. In the deformed crystals two kinds of dislocations were found. One belonged to the slip system of 〈 11 2 ¯ 0 〉 { 1 1 ¯ 01 } . The other had a pseudo helical morphology with a Burgers vector of [0001]. Knoop hardness testing revealed that silicon nitride had isotropic character in terms of hardness. This facts supports the idea that 〈 11 2 ¯ 0 〉 { 1 1 ¯ 01 } is also the primary slip system in silicon nitride at room temperature.