| High temperature tensile property of the extruded Al-20 mass.% Si alloys was investigated to obtain the optimal plastic deformation condition. Al-Si alloys including some amount of Cu, Fe, Mg, Mn were produced by a gas atomization process and hot extrusion at 500 °C was simply applied to the compacted powders without degassing to pursue industrial advantages. The maximum stresses in stress-strain curves of tensile tests at 500 °C increased with increasing strain rate. The highest strain rate sensitivity exponents (m-values) for tensile tests at 500 °C were about 0.3 between strain rates of 10-2 and 10-1 s-1. The fracture surfaces of test pieces showed very fine microstructure and the average grain size was estimated to be about 1 µm. Real elongations, however, were not high (about 30%), though these alloys have fine-grained microstructure and high m-value. The reason will be that uniform deformation was interrupted by voids included in the materials. |
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