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Abstract: Aluminium metal matrix composites were processed by stir casting technique with commercially pure aluminium as the matrix material and 5, 10vol.% of SiC (30μm) particulates as the reinforcement. Al–SiCp composites were subjected to severe plastic deformation through equal channel angular pressing (ECAP). As cast Al–SiCp composites shows uniform distribution of particles and there is no change in the particle distribution after ECAP. It was found that ECAP refines the grain size of matrix material. In Al–5vol.% SiCp composite grain size was reduced to 8μm from 45μm after two ECAP passes whereas in Al–10vol.% SiCp composite grain size was refined to 16μm from 45μm after first ECAP pass. Hardness and compression test were conducted at room temperature to evaluate the mechanical properties of the composites. Both the composites exhibit improvement in mechanical properties after ECAP. [Copyright &y& Elsevier]

Abstract: This study proposes a deformation model to elucidate the deformation behaviors of buck materials during various stages of nano-indentation processes. The deformation model presented in this work can be employed to explain the variation of nanohardness with loading conditions, and to elucidate the pop-in phenomenon during nano-indentation. The effect of holding time on hardness is also explained. Brittle materials, Si wafer, and a ductile material, Al single crystal, are used as test specimens in nano-indentation. The experimental results demonstrate that the deformation mechanism developed in this investigation can explain the deformation phenomena of such materials on the nano-scale. [Copyright &y& Elsevier]