THE EFFECT OF TiB₂ CONTENT ON WEAR AND MECHANICAL BEHAVIOR OF AZ91 MAGNESIUM MATRIX COMPOSITES PRODUCED BY POWDER METALLURGY

Abstract

In this research, AZ91 magnesium matrix composites reinforced with three weight fractions (10, 20, and 30 wt.%) of TiB₂ particulates were fabricated by powder metallurgy using hot pressing technique. The microstructure, density, hardness, wear, and mechanical properties of the specimens were investigated. Microstructure studies showed that fairly uniform distribution of reinforcements was achieved, but partial agglomeration could be clearly seen at 30 wt.% TiB₂. X-ray studies exhibited that phases of Mg, Mg₁₇Al₁₂, and TiB₂ were found. As compared to AZ91, the hardness and wear resistance considerably increased with increasing reinforcement content. The presence of TiB₂ particles improved 0.2% compressive yield strength and ultimate compressive strength (UCS); however, UCS decreased above 20 wt.% TiB₂. Wear mechanisms are oxidative and abrasive.