The effect of different melt treatments on alloying element distribution and mechanical properties of A356 aluminum alloy

摘要

It is widely believed that needle plates of Fe-rich intermetallic compounds decrease the mechanical properties in A356 aluminium alloys. Moreover, the cooling rate has significant effect on the microstructure and the mechanical properties of this alloy and it can make the Fe-rich intermetallic compounds finer. In this research the synergic effect of cooling rate and ultrasonic power and mechanical vibration on the microstructure of A356 has been investigated. Ultrasonic power was applied to the melt by a novel bath type ultrasonic power system. The distribution of alloying elements has also been studied by scanning electron microscope (SEM) and it has been analyzed by EDS. Mechanical properties of samples were investigated by hardness and tensile tests. Results indicate that ultrasonic power effectively modified the microstructure of A356 and it has better efficiency than mechanical vibration. The Fe-rich phases in ultrasonically treated samples had the finest morphologies in the range of 10 micrometer. Ultrasonic power improves mechanical properties of samples even more than mechanical vibration. Comparison the obtained results with the results of other researchers, it is concluded that bath type ultrasonic power system are more effective than probe type ones.