Effects of Mg2B2O5 whiskers on microstructure and mechanical properties of AZ31B magnesium matrix composites

The AZ31B matrix composites reinforced with different volume fractions (1.0, 3.5 and 6.0 vol%) of Mg2B2O5 whiskers were fabricated by stir casting. The microstructure, reinforcement distribution and texture evolution of the as-extruded specimens were investigated by optical microscopy, transmission electron microscopy, scanning electron microscopy, and X-ray diffractometer. Microstructure characterization revealed relatively uniform distribution of reinforcement and significant grain refinement in the composite samples. It was found by X-ray diffractometer analyses that a typical fiber texture with (0002) basal plane parallel to the extrusion direction formed in both AZ31B alloys and Mg2B2O5w/AZ31B composites. The Mg2B2O5 whiskers could weaken the texture and the fiber texture intensity decreases as the Mg2B2O5 whiskers volume fraction increases. Tensile tests along the extrusion direction were carried out at room temperature. It is the first time to find that the presence of Mg2B2O5 whiskers reinforcement could improve both the strength and elongation of AZ31B matrix composites with low volume fraction of Mg2B2O5 whiskers.