Investigation Of Powder Metallurgy Fabrication Processes And Mechanical Properties Of Al-Si-Al₂O₃Composites

In this paper. A1and SiO2powder as raw materials, hot isostatic pressing and hot pressing combined with in situ synthesis method have been used to prepare Al-Si-Al2O3composites successfully. For the development of aluminum matrix composites, it provided new design idea, new preparation process and effective solved the problem of harmful by-products from in situ reaction. It also explored the best sintered process parameters of hot isostatic pressing and hot pressing to prepare this composite. And it has been studied the solid-phase sintering and liquid phase sintering for different silicon content and different size powder of composite and their microstructure features, analyzed the reasons that affect organizational characteristics. At last, mechanical properties of two different silicon content AI-S1-AI2O3composites have been comprehensive analysis, so that the optimized design and perfect preparation process can be provided reference value and basis to prepare more high-performance composites.The metallographic microstructure. morphology and phase composition of AI-S1-AI2O3composites were observed by optical microscopy, SEM and X-ray diffraction analysis. The results show that the uniformity and density of Al-Si-AhOs composites sintering by hot isostatic pressing are better than composites sintered by hot pressing. And the optimal sintering process is that hot outgassing temperature is500℃, and the sintering temperature is550℃then heating-up to700℃only for lh by hot isostatic pressing in order to SiO2in the liquid aluminum rapid completion of in situ reaction and avoid generated Si particles grow up together. This process prepared Al-Si-Al2O3composites can make sure in situ reaction completed and have better microstructure, higher density and reinforcement Al2O3particles distribute uniformly in the aluminum matrix, acicular silicon formation the Al-Si eutectic. With the increase of Si content from1Owt.%to20wt.%,the primary Si phase are appeared in some regions.The different Si content of Al-Si-Al2O3composites prepared by optimal sintering process have been tested its tensile, compression and wear properties. The results show that Si content of1Owt.%and20wt.%composites, their tensile strength were187and 125MPa,their elongation were0.98%and0.07%.so analysis results show that tensile deformation capacity of Al-Si-Al2O3composites is poor and have plasticity is lower with brittle fracture performance characteristics. And their average compressive yield strength were216and300MPa, composites show to have some compressive strength and resilience, and plasticity can reach39%and7%respectively. For wear resistance, the silicon content of10wt.%composite, the friction coefficient is greater than the silicon content of20wt.%composites, but the wear rate is relatively smaller. With loads increase, the dominant wear mechanism of Al-Si-Al2O3composites has changed from abrasive wear to adhesive wear.