Fatigue crack growth behavior and mechanisms in α-β-SiAlON at high temperature

Experimental results are presented on subcritical crack growth under sustained and cyclic loads in gas pressure sintered α-β-sialon at 1200°C. High temperature subcritical crack growth behavior is examined by application of controlled surface cracking technique from Vickers indentations in bars loaded in 4-point bending. Electron microscopy analysis in the crack-tip damage zone indicates that creep mechanisms such as cavity formation are responsible for static fatigue and dislocation plasticity may play a certain role in high temperature cyclic fatigue fracture.