Roberto Figueiredo

Abstract:

The high compressive stresses imposed by high pressure torsion allows plastic deformation of machine chips and metallic particles until close contact is reached. The severe torsion straining provides the condition for "self-welding" of these particles, creating a continuous metallic matrix. This technique has been used to produce aluminum matrix composites [1, 2] and has also been used to consolidate magnesium particles [3]. Processing magnesium by high pressure torsion is especially interesting since it has been shown that it leads to exceptional ductility [4]. The present work describes the use of high-pressure torsion to consolidate magnesium with reinforcement phases into metal matrix composites. The microstructure of the composite was evaluated by scanning electron microscopy and the mechanical strength was estimated by microhardness testing. It is shown that a dense microstructure is attained after several turns of torsion, and the hardness of the processed composite is higher than the pure metal base. The present work shows that it is possible to improve magnesium strength by introducing hard phases during high pressure torsion consolidation of particles.