Effects of untreated

Sr and B modification

ultrasonic treatment and compound treatment of ultrasonic and modifier on microstructure and mechanical properties of as-cast and T6-state Al-6 Si-3 Cu-0.3 Mg alloy were investigated.Effects of different ultrasonic power and treating time on microstructure and mechanical properties of as-cast and T6-state alloy under compound treatment condition were also analyzed.The results show that modification

ultrasonic treatment and compound treatment can all improve microstructure and mechanical properties of the as-cast and T6-state alloy

however

the effect of compound treatment presents the most remarkable.Compared with those of the untreated alloy

the tensile strength and elongation of as-cast alloy are increased by 10.3%and 57%

respectively

while those of T6-state alloy are increased by 33.4% and 12.9%

respectively.In the range of 0～900 W

with the increase of ultrasonic power

as cast primaryα-Al phase and T6-state eutectic Si are refined gradually.In the range of 0～90 s

with the increase of treating time

as cast primaryα-Al phase and T6-state eutectic Si are refined at first and then coarsened

and the turning point is 30 s.Under different conditions

the tensile strength of as-cast alloy is change slightly

however

as-cast elongation

T6-state tensile strength and elongation of the alloy correspond to its microstructure change law.