Parametric Influence of Friction Stir Processing on Microstructural Evolution and Tensile Behavior of AZ31/Ti-6Al-4V Magnesium Matrix Composites

Abstract

Titanium alloy Ti-6Al-4V particles were used as reinforcement for AZ31B magnesium metal matrix composites (Mg MMCs) which were synthesized via friction stir processing (FSP). Ti-6Al-4V particulates were packed in the machined grooves at first and subsequently processed by means of a traditional machine used for vertical milling. The processing speed and the repeated passes were considered as the major processing factors to vary during processing apart from the content of Ti-6Al-4V particles. Optical and scanning electron microscopes were used to record the evolved microstructure of the composites. Changes in Ti-6Al-4V particle distribution across the stir zone resulted to form several kinds of microscopic regions. The distribution of particles became inhomogeneous as the traverse speed was advanced to higher level. Conversely, the distribution became homogeneous with every pass. The role of selected process variables on the tensile behavior was analyzed. Mg MMCs that were prepared at lower traverse speed (30 mm/min) and higher number of passes (5) showed higher properties during tensile test. The micrographs of the fracture surfaces were studied to understand the mode of fracture.