Development of titanium particulate reinforced AZ31 magnesium matrix composites via friction stir processing

Friction stir processing (FSP) was applied to develop pure titanium (Ti) particulate reinforced AZ31B magnesium matrix composites (MMCs). Machined groove strategy was used to pack the Ti particulates initially and FSP was carried out using a conventional vertical milling machine. Traverse speed, number of passes and volume fraction of Ti particulates were varied. The microstructural evolution was observed using optical and scanning electron microscopy. Different microstructural zones were identified in the stir zone based on the distribution of Ti particulates. In general, the tendency to form clusters decreased at lower traverse speeds and higher number of passes. The increase in traverse speed and number of passes refined the grains of the magnesium matrix. The variation in the tensile behavior due to the chosen process parameter was explored. The composites fabricated at a traverse speed of 30 mm/min and 5 passes demonstrated highest tensile strength and elongation. The details of fracture surface and fracture mode were further reported.