EFFECTS OF ULTRASONIC TREATMENT ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HYBRID PARTICULATES REINFORCED AL-ALLOY MATRIX COMPOSITES

摘要

The effects of ultrasonic treatment (UT) on the microstructure and mechanical properties of 10 wt.% Mg_2Si+1 wt.% nano-sized SiC particles (SiC_(np) for short) hybrid reinforced Al-Cu alloy matrix composites were investigated for the first time. The results show that after UT, the big eutectic Mg_2Si phase was remarkably refined, from coarse Chinese characters (about 50 μm) to fine strips or dots (about 0.5～2 μm). Meanwhile SiC_(np) agglomerations were also eliminated, and both Mg_2Si phase and SiC_(np) were uniformly distributed in the composites. The as-cast ultimate tensile strength (UTS) and elongation of hybrid Mg_2Si+SiC_(np)/Al-Cu composites fabricated by combining UT and squeeze casting (SC) were enhanced to 336 MPa and 3.0%, which were increased by 31.3% and 130.8%, respectively, compared with the composites without UT. The UTS of the hybrid Mg_2Si+SiC_(np)/Al-Cu composites was also 33.5% higher than that of the Al-Cu matrix alloy and 23.5% higher than that of 1wt.% SiC_(np)/Al-Cu composites prepared by the same process.