Titanium particulate reinforced AZ31 magnesium matrix composites with improved ductility prepared using friction stir processing

Abstract

Conventional ceramic particulate reinforcements cause a major loss in ductility of magnesium matrix composites (MMCs). Metallic particles possessing higher melting point can offer a solution to this issue. Titanium (Ti) particles (0,7,14 and 21 vol%) were reinforced into magnesium alloy AZ31 using friction stir processing (FSP) performed by a conventional sturdy vertical milling machine. The microstructure and the tensile behavior of the fabricated composites were studied in detail. The micrographs revealed a uniform distribution of Ti particles all over the stir zone irrespective of the volume content of Ti. Ti particles did not decompose or react with the matrix and its alloying elements. Ti particles established a proper interface with the matrix AZ31. Ti particles survived the severe plastic strain without breakage. The grains in the matrix were refined extremely because of dynamic recrystallization and the pinning effect of Ti particles. A large number of dislocations are found in the composite. Ti particles improved the tensile strength of the composite and helped to retain appreciable ductility.