Surface moderation and composite fabrication of die-cast magnesium alloys via friction stir processing: a review

Abstract

ABSTRACT The low density of Mg alloys (~ 1.8 g/cm3) along with high strength, high elastic modulus and good capability to resist impact load than aluminum alloys make them a suitable candidate for aerospace, automotive and nuclear industries. The statistical data collected from the web of science core collection reveals that 90% of Mg alloys are fabricated by the die casting process. These die casting alloys are largely used in automotive components. Moreover, their low mechanical (tensile strength and ductility) and tribological properties (low wear and corrosion resistance) limit their use in aerospace and nuclear industries. The said issues are addressed by surface treatments with the addition of rare earth elements (RE). However, the higher addition of RE elements has two major issues. The first one is the expensiveness of RE and the second one is the increase in density of reinforced alloys. Therefore grain refinement and fabrication of surface metal matrix composites (MMCs) by Friction stir processing (FSP) has been considered as an effective approach to overcome the issues associated with die-cast magnesium alloys. This review paper presents the state of the art of enhancing mechanical and tribological properties of die-cast AZ and RE series magnesium alloys through FSP.