Constitutive equations for superplastic deformation of SiC particulate reinforced aluminum alloys

Superplastic deformation mechanism in particulate reinforced aluminum alloy matrix composites was analyzed under the light of dislocation movements. The superplastic behavior of some particulate reinforced aluminum alloy based composites and the corresponding monolithic aluminum alloys was compared in view of strain rate, optimum testing temperature and the relationship between flow stress and strain rate. Under the consideration of the accommodation process for dislocation movements, the constitutive equations for superplastic deformation at temperatures below and above the solidus temperature of the composite were developed. To verify the theoretical predictions, superplastic tensile tests were conducted on the SiCpreinforced 8090 aluminum alloy composite. Experimental results of the stress-strain relationship obtained at temperatures near to the solidus temperature of the composite compare well with the theoretical constitutive predictions.