The effect of processing parameters on the tensile properties of alumina fiber reinforced magnesium

Abstract

The effect of processing variables on the tensile properties of commercially pure (CP) magnesium reinforced with FP alumina fibers has been studied. Composite plates were cast at 698°C, 755°C, and 810°C, with a five-minute hold period prior to solidification. The properties of the composites were compared to those of both conventionally cast CP magnesium and ZE41A (Mg-4.25Zn-0.5Zr-1.25RE) composites. The tensile properties were found to be independent of casting temperature in the range 698 to 810°C, although the five-minute hold period significantly decreased the axial properties of the CP magnesium. The results indicated that, during processing, the time at temperature has a more pronounced effect on tensile strength than the actual casting temperature. Increasing casting temperature was found to increase the MgO fiber-matrix reaction zone to a size comparable to that observed in conventionally processed ZE41A material. However, the strengths of the CP magnesium composites cast at the three different temperatures were significantly lower than that of ZE41A, indicating that the interfacial strengthening observed in ZE41A is not due to larger MgO reaction zone particles. A possible explanation for the interfacial strengthening in ZE41A is the presence of zinc and aluminum in low concentrations, which act to enhance the bonding between the reaction zone and the metallic matrix.