Micromechanics modeling of creep fracture of zirconium diboride-silicon carbide composites at 1400-1700°C

The creep deformation of the ultra-high temperature ceramic composite ZrB₂-20%SiC at temperatures from 1400 to 1700°C was studied by a micromechanical mode in which the real microstructure was adopted in finite element simulations. Based on the experiment results of the change of activation energy with respect to the temperature, a mechanism shift from diffusional creep-control for temperatures below 1500°C to grain boundary sliding-control for temperatures above 1500°C was concluded from simulations. Also, the simulation results revealed the accommodation of grain rotation and grain boundary sliding by grain boundary cavitation for creep at temperatures above 1500°C which was in agreement with experimental observations.