Formation of surface metal matrix composite AZ91/MgxCuy and its wear behavior after T heat treatment

in this study, in situ surface composite based on Mg-Cu system produced on AZ91C alloy by friction stir processing. Microstructural studing in the 6 passes friction stirred zone, revealed the presence of Mg2Cu intermetallic phase in AZ91/Cu nanocomposite. after T6 heat treatment, microhardness value within the stirred zone increased due to increasing volume fraction of hard intermetallics and formation of MgCu2 phase in the composite. Wear surface and debris observation indicated that abrasion and delamination wear mechanisms occurred in AZ91C alloy. The results of EDS and microhardness test on AZ91/Cu sample revealed that hardness and durability of oxide film on wear surface was more than that of the base alloy, which led to decrease wear mass loss of the composite in comparison with base metal. the results of wear test revealed that T6 heat treatment weakened wear properties, compared with not heat treated composite. composite samples Wear rate increased because of microcrack formation during heat treatment which caused delamination occurrence in this wear sample.