Texture and microstructural changes after thermal cycling of 6061Al-20vol%SiCw metal matrix composite: The role of microscopic internal stresses

The dramatic texture and microstructural changes observed in 6061Al-20vol%SiCw metal matrix composite undergoing severe thermal cycles, under the absence simultaneous action of an external tensile stress, are studied. Under only cycles (100–450 °C) homogenization disorientation SiC whisker reinforcement crystallographic randomization occurs. However, when a stress is applied, whiskers rotate so that their long direction aligns with axes. Furthermore, strong large deformations (superplasticity), higher than 1000%, achieved. These results explained on basis microscopic fields generated at different scales (stresses type II III) well-known observation dislocation generation SiC-metal interface during cooling period cycles. We propose moving dislocations (responsible III stresses) operate differently or presence stress. no motion (occurring mainly heating period) driven by internal improved leading to elongations. Despite low it overcomes effect stresses for motion.