Research On The Microstructure And Properties Of Modified Cemaric-Powders Reinforced Cast Al-Si Alloy

Aluminum alloy has the advantage of low density,high specific strength and stiffness,excellent electrical properties and thermal performance,good corrosion resistance.ZAlSi7Mg is one of the most widely used in casting aluminum alloy,it is commonly used in casting Al-Si-Mg alloy,it has excellent casting property,like good mobility and air tightness,small shrinkage and hot cracking tendency,after modified and heat treatment,it has merits of mechanical property,physical property,corrosion resistance and medium machining performance.it is a large number of applications in the field of space flight,aviation,military,industry,agriculture and transportation.But,with the rapid development and step foreward of industry,materials do not reach use performance in the case of more and more high requirements of materials,so it needs to use new technology to improve its properties.This paper added modified ceramic powders into ZAlSi7Mg alloy,modified powders showed they improved microstructure of the alloy,refined eutectic silicon,improved the mechanical properties and wear resistance of the alloy.Adding different amounts of modified ceramic powders to ZAlSi7Mg melt,when adding modified ceramic powder BN,grain is refined,mechanical properties and wear resistance is varying degrees of improvement,when the powder is added in an amount of 0.1%,the alloy obtains relatively best microstructure,achieves the best performance,the tensile strength increases by 7.8%,Brinell hardness increases by 19.2%,the lowest rate of weight loss,which is the best wear resistance;when adding the modified ceramic-powder TiB2,the alloy microstructure has been significantly improved,reducing the mechanical properties and wear resistance after the first increase,when the powder is added in an amount of 0.1%,the alloy obtains relatively optimum microstructure,the overall performance is best,the tensile strength increases by 10.2%,Brinell hardness increases by 29.73%,the weight loss rate is relatively low;when adding the modified ceramic powder TiC,eutectic silicon turns from needle-like to short rod-like,mechanical properties and wear resistance improve,when the powder is added in an amount of 0.2%,the overall performance is best,the tensile strength increases by 6.35%,Brinell hardness increases by 13.33%,the rate of weight loss is the lowest.Studies have shown that in the solidification process the modified ceramic powders increase the nucleation,refine grains,change the friction mechanism which turns from two-body to three-body friction,the main friction form is abrasive wear.