Effects of different solution processes on microstructure and properties of rapidly solidified hypereutectic Al-Si alloy strips

which were prepared by single roller melt-spinning method

were investigated by scanning electron microscope（SEM）and transmission electron microscope（TEM）.The results indicate that compared with as-cast microstructure

micro-nanocrystal hypoeutectic phase in rapidly solidified hypereutectic Al-Si alloy can be observed and α-Al phase is prior to precipitate from the Al-Si alloy

which is attributed to rapid solidification restraining the nucleation and precipitation of Si phase in the alloy.Furthermore

in the process of solution treatment

Si element can be precipitated from the matrix and gradually aggregated to generate fine silicon particle

which was uniformly distributed into the matrix

with extending holding time.Desirable fine silicon particle with high spheroidization rate can be observed in the alloy with holding for 100 min at 480℃ followed by quenching in water and natural aging for 96 h

which makes maximum hardness of HV 241.67 for the alloy.