High Silicon Aluminum Alloy Preparation Process And Organizational Performance Research

The feasibility of high-Si aluminum alloys preparated by powder metallurgy methods were studied mainly in this experiment, which include mechanical alloying, press-shaping, sintering, etc.The properties of the material were tested by laser particle size analyzer, SEM, hardness tester, bending strength tester, OM, etc. The influencing factors such as ball milling media, milling time, ball-feed ratio, milling speed and so on were studied during mechanical alloying; and the effects of pressure and sintering temperature on properties were studied mainly in preparation process; In addition, other phenomena such as peeling, bubble, the way of sintering, density change and the changes in shape and size of Si-phases during sintering were analysed. The results show that:(1) The material of milling ball is chose finally by steelcore inside and polyurethane covering with, and the milling media is alcohol according to the experiment resultes of mechanical alloying.The better ball milling conditions:milling speed is150r/min, milling time is12h, ball-feed ratio is15:1, respectively.(2) The main influencing factor during mechanical alloying is milling speed through the orthogonal experiment, and according to the single factor single experiment, higher milling speed doesn’t mean better properties.The effect of mechanical alloying turns to be bad when milling time extends through SEM analysis.(3) According to the design and analysis of exploratory experiment and orthogonal experiment, the better ball milling conditions:pressure is250Mpa, sintering heating curve is3,final sintering temperature is1000℃, respectively.(4) The pressure and final sintering temperature have lager effects on material properties throughl properties analysis. Because the lacking of hot pressing sintering equipments,density does not reach the standard required,which leads to low thermal conductivity, which does not reach the practical application effect.If hot pressing sintering method is used, it will lead to high density and thermal conductivity and low porosity.(5) Sintering process is complex,and during which, growth mechanism of silicon particle results in lager primary silicon particle.In order to reform material properties, the primary silicon should have smaller size and equal distribution.It needs to use the follow-up treatment method(such as pressing) to low primary silicon size and distribute equally in the material.