中文摘要：

用直接超声振动法处理了Al-17Si-xFe（x=2,3,4,5,质量分数）合金,利用光学显微镜、XRD及EDS等手段分析了传统铸造工艺和超声半固态成形合金的微观组织。结果表明,在无超声振动时,Fe含量为2%的铸态合金组织中的富Fe相以长针状β-Al5FeSi相为主,伴有少量板条状δ-Al4FeSi2相。随着Fe含量的增加,合金组织中长针状β-Al5FeSi相逐渐减少,针片状δ-Al4FeSi2相逐渐增多,Fe含量为5%时以粗大针片状δ-Al4FeSi2相为主。在液相线附近对上述不同Fe含量的合金熔体施加一定时间的超声振动后浇注到金属型,富Fe相均以块状和短条状δ-Al4FeSi2相为主,其晶粒平均等效直径在18～46μm之间,明显细化,此外还伴有少量针状β-Al5FeSi相。初步探讨了超声振动影响富Fe相形貌的作用机理。

英文摘要：

The hypereutectic Al-17Si alloys containing 2%,3%,4%,5%Fe（Wt.%） were treated by direct ultrasonic vibration（USV） treatment.The microstructures of the alloys which were produced by conventional casting process and semi-solid forming with USV treatment were investigated by OM（optical microscope）,XRD（x-ray diffraction）,and EDS（energy dispersive spectrometer）.The results reveal that a large amount of long needle-like β-Al5FeSi phase with a little plate-like δ-Al4FeSi2 phase can be observed in the as-cast Al-17Si alloy containing 2%Fe without USV treatment.With the increase of Fe content,the amount of long needle-like β-Al5FeSi phase is decreased gradually,and the plate-like δ-Al4FeSi2 phase is increased in the Al-17Si alloys.The coarse plate-like δ-Al4FeSi2 phase is dominant in Fe-rich phases in the Al-17Si alloy containing 5%Fe.The alloy melt with different Fe content was treated by USV near the liquidus temperature for a certain time,and then was poured into a permanent mold.The results indicate that blocky and short-rod δ-Al4FeSi2 phase is dominant in Fe-rich phases,and the average grain size of δ-Al4FeSi2 phase is refined to 18~46μm,and a little needle-like β-Al5FeSi phase is remained.The mechanism of USV refining Fe-rich phase in the Al-17Si alloys was discussed.