Microstructure and Mechanical Properties of a Nanostructured Al-Si-Fe Based Alloy Fabricated by Powder Metallurgy

摘要

The Al-Si-Fe based alloy powers produced by rapid solidification process were fabricated successfully without showing processing defects such as cracks or porosities through consolidation at 673 K and 588 K by hot extrusion with various extrusion ratios. The microstructure was observed to be composed of Al matrix phase and four kinds of dispersoids, i.e., supersaturated Si, Al_5FeSi, Q phase (Al-Si-Fe-Mg base intermetallic compound) and Al_4Cu_2Mg_8Si_7. Those particles were found to be distributed within the grains and also at grain boundaries. With decreasing temperature or increasing extrusion ratio of hot extrusion, grain refinement to nano-scale could be achieved in the present alloy. The alloy having finer grain size showed higher yield strength in the low temperature region but slightly lower yield strength in the high temperature region. Details would be discussed in correlation with the results obtained.