Abnormal grain growth during annealing in the Al/Al₂O₃ composite produced by accumulative roll bonding

Abstract

The mechanical and physical properties of composites are related to the matrix microstructure and reinforcements dispersion. Microstructural evolution during annealing can change the properties of the composites. Consequently, in this paper, the microstructural evolution of Al/Al 2 O 3 composite during annealing and the interpretation of metallurgical phenomena were investigated. Accumulative roll bonding technique was used for manufacturing the Al/Al 2 O 3 composite. The Al/Al 2 O 3 composite specimens were further annealed at 375°C for 15, 30 and 60 min without any protected atmosphere. The grain orientation (texture) and the grain size of the composites were investigated. Results showed that by increasing the annealing time to 60 min, abnormal grain growth started. Moreover, the frequency of low angle boundaries (1.5-5) increased, while the frequency of ∑3 Coincident Site Lattice boundaries decreased. In fact, grain boundaries with low Coincident Site Lattice were less prone to reinforcement pinning. Then low Coincident Site Lattice boundaries were more susceptible to formation and growth of abnormal grains.