Effect of friction stir back extrusion on direction-dependent properties of gradient AZ91-bioactive glass composite rod

Abstract

This research investigated the microstructure, mechanical properties, and corrosion resistance of friction stir back extruded AZ91-bioactive glass composites in parallel and perpendicular directions to the extrusion direction. The results showed that small grains are observed on the lateral surface, especially where bioactive glass is more prevalent. The grain size increases toward the center of the composite rod. The grain size and relative content of the β-Mg17Al12 phase shift from 30.2 ± 2.3 μm and 0.45 on the lateral surface of the composite rod to 37.4 ± 3.2 μm and 0.12 at the center of the composite rod, respectively. The corrosion resistance and hardness of the lateral surface area of the composite rod are 23 and 26%, respectively, higher than the corrosion resistance and hardness of the transverse surface. The lateral surface of the composite rod shows 74% higher corrosion resistance than the lateral surface of friction stir back extrusion processed wire without bioactive glass particles.

Keywords

• Friction stir back extrusion
• Direction-dependent properties
• AZ91 alloy matrix composite
• Corrosion properties