SUPERPLASTIC CONSTITUTIVE EQUATION AND RATE-CONTROLLING PROCESS IN ALUMINUM-MATRIX COMPOSITES WITH DISCONTINUOUS FIBER AND PARTICLE REINFORCEMENTS

Superplastic behavior of aluminum matrix composites with discontinuous reinforcements has been investigated in a temperature range below the melting temperature measured by differential scanning calorimetry. Th e experimental results of the mechanical properties revealed that the rate-controlling process of superplastic flow was associated with disl ocation movement controlled by lattice self-diffusion. The strengtheni ng due to the presence of reinforcements was retained, It is suggested that the strongest strengthening process of the dislocation-pileup me chanism and the diffusional relaxation-limitation or dislocation bypas s mechanism affects the rate-controlling process.