Abstract
This paper studies the mechanical properties enhancement of AM60/ Al₂O_3p magnesium metal-matrix nanocomposites by Equal Channel Angular Extrusion (ECAE) that is a useful technique to produce bulk nano-structured materials by severe plastic deformation. The present magnesium metal matrix composites (Mg MMCs) with 1, 2 and 5 wt.% of nano-sized Al₂O₃ particulates for ECAE were fabricated using stir-casting method. Observing the microstructures of MMCs, the more uniform microstructure consisting of grains with an average grain size of ~0.8 μm was observed in the AM60/5wt.% Al₂O_3p MMC after 4 passes. The hardness of MMCs increases evidently with the increase of the weight percentage of Al₂O_3p additions and ECAE passes. The optimal hardness of AM60/5wt.% Al₂O_3p MMC after 4 passes increased to 103.7 HV, which is by 87.2 % higher than that of as-cast AM60.

Key words
grain refinement, ECAE, metal matrix composites, magnesium alloy, nano-scaled aluminum oxide

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