Effect Extrusion Deformation On Properties Of Al-Si-Cu Alloy Produced By Rapid Solidification And Powder Metallurgy Methods

Powder metallurgy(PM)aluminum silicon alloy material has low density,high specific strength,low coefficient of thermal expansion,excellent corrosion resistance,which satisfy the requirement of automobile lightening in the future,and it has a widely application prospect.Compared with traditional casting method,the shrinkage cavity and porosity were not formed by PM technology.Compared with traditional forging method,the manufacturing and mould cost decrease,which was used as a near-shape machining technique of the part.In this paper,the alloy blank was prepared by rapid solidification of the Al-Si pre-alloy powder and Cu powder,then the forward extrusion of the alloys blank was processed by different extrusion ratio with the certain temperature,and the following different condition sintering was imposed.The analysis of metallographic phase and microstructure was obtained by OM,XRD and SEM,and the mechanical properties of the material were measured.In this paper,the size distribution of the mixed Al-Si powder and pure Cu powder particle was analyzed by laser particle size analyzer.The average particle size of the mixed powder is 50.22 μm and the mid-value is 35.06μm.The main phase of mixed powder is α-Al,β-Si,Cu4 Si,CuAl2 by the analysis of the XRD and SEM.The investigations show when the extrusion ratio of Al-Si-Cu alloy compact was 10.38,the density was enhanced from 2.450g/cm3 to 2.680g/cm3,and achieved the 98.7% of theoretical density.After 1.5h sintered at the temperature of 525 with protection of N℃2,the density of alloys was 2.650g/cm3,and reached 98% of theory density.After proceeding aging treatment for 8,the vickers hardness of the alloys was 56 HV,and the best tensile strength was 400 MPa,and the extension rate of the alloy was 13.8%,which was much higher than the current strength of Al-Si-Cu powder metallurgy.With the increase of aging time,the strength increased.With the increase of extrusion ratio,the strength increased.The phase structure of alloys was α-Al,β-Si,CuAl2 and Cu4 Si.CuAl2 and Cu4 Si,which had a good strengthening effect in the matrix.It proved that during the extrusion process the surface oxide film of the aluminum silicon alloys powders was broken,and a completed metallurgical bonding was achieved in the subsequent sintering process.Aluminum Alloys powder metallurgy sintering difficult was solved.