Texture and Microstructure Evolution During Superplasticity of the Metal Matrix Composite PM 2014 Al–20% Al2O3

The effects of superplastic deformation (SPD) on grain structure and texture evolution of the Al 2014–20%Al2O3 composite produced via powder metallurgical method were investigated in conjunction with surface relief observations. Samples were deformed in tension at different strains in the range of true strain rates 10-4–100 S-1 at temperature 500C. It was found that SPD strains have a large effect on both texture and grain size. At the initial stage of superplastic flow, deformation bands are formed in the aluminum matrix along the tension direction. Simultaneously, the initial 〈 111 〉 fiber texture is broken and formation of 〈 110 〉 fiber texture takes place. Further strain up to 50% leads to grain structure change from banded structure to nearly equiaxed. The 〈 111 〉 fiber texture is restored and texture intensity decreases with increasing strain. Strain rate dependence of texture developments showed evidence for dislocation activity in examined strain range.The relation between microstructure evolution and texture development during superplastic deformation of the PM 2014–20% Al2O3 composite is explained from the viewpoint of cooperative grain boundary sliding (CGBS).