The Growth And Feature Of Primary Si In High-Si Al Alloys Prepared By RS/SPS And Its Effect On Mechanical Properties

High-Si Al alloys are candidate materials for automotive, aerospace, and electronics applications due to their excellent physical and mechanical properties, such as low density, high stiffness and good wear resistance.At this stage, the Si phase in the high silicon cast aluminum alloy internal structure is always has big sized, and it is one of the factors stacking against mechanical properties. Studies show that modification or rapid solidification method can help the fine Si phase formed in high-Si Al alloys, and the formation of dispersive distribution of fine primary Si particles helps increasing the mechanical property. To get the uniform fine microstructure of high-Si Al alloys, first step is prepared ribbon alloys by rapid solidification, after then it was sintered into blocks materials in the Spark Plasma Sintering machines. It will promote the application of high-Si Al alloys in industry.In this paper, the Al100-xSix (x=25-35) binary alloys were prepared by the melt-spun method. The microstructure of ribbon alloys and the growth mechanic of spherical primary Si under the variety detection methods (such as SEM, TEM) are discussed. The growth mechanism of spherical primary Si has been preliminarily revealed, by discussing the influence of the solute redistribution change in the rich-Si area under conditions of the proper cooling rate and Si concentration.Fabricating the bulk high-Si Al alloys with Spark Plasma Sintering method, the uniform fine microstructure of sintering materials can be prepared by optimizing the experimental parameters, and some excellent performance of ribbon was remained in alloys after sintering. Al65Si35 alloys is made under the condition of 543 K and 500 MPa, and the density is 98.2%, micro hardness is 198.9 HV, wear is 0.817×10-14m3N-1m-1.