Microstructure and properties of in situ generated MgAl2O4 spinel whisker reinforced aluminum matrix composites

In this study, a novel MgAl2O4 spinel whisker reinforced composite was synthesized in situ in an Al matrix by a powder metallurgy technique. In MgAl2O4/Al composite, the whisker content was varied from 3% to 15% in weight and each one was completely investigated. The as-produced MgAl2O4/Al composites were hot extruded and MgAl2O4/Al composites rods with high relative density were obtained. Both the hardness and the softening temperature of the composites increased with increasing content of MgAl2O4 whisker. The dilatometric measurements show that MgAl2O4 whisker reinforced Al composites exhibit better thermal stability and lower thermal expansion coefficient than aluminum alloys. Moreover, wear resistance is also enhanced due to the formation of the whisker-formed network structure which is capable of bearing and transferring abrasion effect. Thus, the enhanced properties of the composites could be obtained.

► MgAl2O4 whisker was in situ generated in Al matrix through powder metallurgy.
► The composites exhibit a better thermal stability than aluminum alloys.
► The wear resistance enhances with an increasing content of MgAl2O4 whisker.