Effects of Mg_2B_2O_5 whiskers on microstructure and mechanical properties of AZ31B magnesium matrix composites

摘要

The AZ31B matrix composites reinforced with different volume fractions (1.0, 3.5 and 6.0 vol%) of Mg_2B_2O_5 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 Mg_2B_2O_5w/AZ31B composites. The Mg_2B_2O_5 whiskers could weaken the texture and the fiber texture intensity decreases as the Mg_2B_2O_5 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 Mg_2B_2O_5 whiskers reinforcement could improve both the strength and elongation of AZ31B matrix composites with low volume fraction of Mg_2B_2O_5 whiskers.