Study On Preparation And Structure Property By High Pressure Torsion Of SiCp/Al Composites

SiCp/Al alloy composites reinforced with low density, high specific strength,low coefficient of thermal expansion, good wearing resistance, good thermalconduction and electrical conduction has a wide range of applications in theaerospace, automobile engine, electronic packaging. Currently, net shapepreparation in SiCp/Al alloy composite has made certain achievements at home andabroad near. But there is still no reports about prepareing double size distributionSiCp/Al alloy composite by High-Pressure torsion. In this paper, high pressuretorsion of high hydrostatic pressure and shearing deformation capacity is used toprepare a single size and double-size particles of SiCp/Al alloy composites.Metallographic observation, relative density and microhardness testing are used toanalyse the influences of different process parameters on microstructures andproperties of single size and double size particulate composite.Results show that, with the distance from the center of the sample, thepressure, the number of revolutions increases, shearing action and equivalent strainincreases, the clusters of SiC particles decrease, the homogeneous of thedistribution is improved. microhardness gradually increases. But if the pressure istoo large, SiC particle will be prone to broken and fracture. The higher particlevolume fraction of SiC particles, the less homogeneous of the distribution and themore clusters of SiC particles are. The increasing shearing action can reduce theclusters of SiC particles. Under the high hydrostatic pressure and shearingdeformation capacity, the small SiC particle size, the high homogeneous of thedistribution is. When SiC particle size is increased, the effective shearing actioncause SiC particles fractured easily because of their own defects. The samedistance from the center of the sample, Microhardness of single size particulatecomposite, which has a peak with increasing volume fraction of SiC particles, andthe peak will decreases with the increasing of the particle size.When the size gap between the two-particle size is small, the particles havethe similar flowing power. When the gap is large, the difference of flowing poweris large. The obstructive influnce of coarse particles to fine particles is increased.With increasing volume fraction of coarse SiC particles, clusters of SiC particles are fractured under shearing deformation capacity, the homogeneous of thedistribution is improved. As the increasing volume fraction and siza of coarse SiCparticles, microhardness of double-size particles of SiCp/Al alloy composites has apeak. Keeping on increasing volume fraction and size of coarse SiC particles,microhardness of double-size particles of SiCp/Al alloy composites reducesconstantly.