Effect of mechanical mixing on the microstructure and mechanical properties of Al-based metal matrix composites reinforced with nanocrystalline Al-Ca intermetallics

Abstract

Al-based metal matrix composites reinforced with 40 vol.% of nanocrystalline Al- Ca intermetallic particles were synthesized by hot pressing followed by hot extrusion process and the effect of manual blending as well as mechnical mixing on microstructure and mechanical properties was studied. Microstuture reveals that mannual blending leads to the agglomeration of Al-Ca intermetallic particles and on the other hand, the composites prepared by milling display a more homogeneous distribution of the reinforcing particles. Mechanical mixing has a strong impact on the mechanical properties. The strength increases from 112MPa for pure Al to 250 and 415MPa for the composites produced by blending and milling respectively. This behavior is linked to the reduced matrix ligament size characterizing the milled composites.