Abstract

The bi-materials with Al-Mg alloy and its composites reinforced with SiC and Al_2O_3 particles were prepared by conventional powder metallurgy method. The A1-5 wt%Mg and composite mixtures were compacted under 150sim450;MPa, and then the mixtures compacted under 400 MPa were sintered at 773sim1173K for 5h. The obtained bi-materials with Al-Mg/SiCp composite showed the higher relative density than those with Al-Mg/Al_2O_3 composite after compaction and sintering. Based on the results, the bi-materials compacted under 400 MPa and sintered at 873K for 5h were used for mechanical tests. In the composite side of bi-materials, the SiC particles were densely distributed compared to the Al_2O_3 particles. The bi-materials with Al-Mg/SiC composite showed the higher micro-hardness than those with Al-Mg/Al_2O_3 composite. The mechanical properties were evaluated by the compressive test. The bi-materials revealed almost the same value of 0.2% proof stress with Al-Mg alloy. Their compressive strength was lower than that of Al-Mg alloy. Moreover, impact absorbed energy of bi-materials was smaller than that of composite. However, the bi-materials with Al-Mg/SiCp composite particularly showed almost similar impact absorbed energy to Al-Mg/Al_2O_3 composite. From the observation of microstructure, it was deduced that the bi-materials was preferentially fractured through micro-interface between matrix and composite in the vicinity of macro-interface.

• Keywords: Ball-milling;Aluminum-magnesium alloy;SiC and Al_2O_3 particles;Macro- and micro-interface;Density;Compressive and impact properties;