Study On Fabrication And Wear Behavior Of Mg₂Si And SiC_p Hybrid Reinforced Aluminum-matrix Composites

The traditional single-phase materials have become increasingly unable to meetthe requirements of the mechanical properties with the rapid development of theaviation, aerospace and communications equipment. Particle reinforced aluminummatrix composites has speedy development because of its high specific strength, highspecific modulus, high wear resistance and low coefficient of thermal expansion, etc.At present, SiC_preinforced aluminum matrix composites which have beenextensively applied are mostly fabricated by directly adding methods, but thesemethods not only have a complex process, poor compatibility between the particlesand the matrix but interface adverse. But in-situ Mg₂Si/Al composite has hightoughness and high temperature performance because it’s fine-grain and goodinterfacial bonding. In order to obtain high comprehensive performance and tomaintain the advantages of the two materials, this paper combine this two methods tofabricate a hybrid reinforced aluminum matrix composite.In this paper, first, adding pure Mg into the melt Al-Si alloy, then add pretreatedSiC power into the melt alloy by mechanical stirring, thus fabricated the compositeswe need.Firstly, we study on the effect of different stir process parameters on theproperties of the composites to choose the best process. The stirring speed is400r/min, stirring time is30min, and stirring temperature is700℃. Secondly, we usethe best process to fabricate composites with0wt.%SiC,5wt.%SiC,10wt.%SiC,15wt.%SiC and20wt.%Mg₂Si and study on the effect of SiC particle on primaryMg₂Si, α-Al and the eutectic. Results: The polygon blocks primary Mg₂Si gradually ucleation substrates. The α-Al regular dendrite break down and gradually round,inally, become into spherical or ellipsoidal, the size further refine. Strip eutecticg2Si disappears and in final all showing punctuate or granular features, the contentsf eutectic Mg₂Si are decrease. We can’t find any eutectic Mg₂Si when the content ofiC is15wt.%. With the increase of SiC, the smaller of the eutectic Si and dendriteutectic Si gradually decrease and show chrysanthemum.This paper also study on the hardness and wear resistance of the composites. Theardness results show that the hardness of （Mg₂Si+15wt.%SiC）/Al increased by8.4%than the Mg₂Si/Al. The results of wear resistance show that with the increasef the SiC contents the wear rate decrease and the wear resistance significantlymproved. The wear resistance of （20wt.%Mg₂Si+15wt.%SiC）/Al increased by nearlywice than20wt.%Mg₂Si/Al, the wear resistance of other two composites is also betterhan20wt.%Mg₂Si/Al. The is because the composites not only have Mg₂Si phase butlso SiC particles which are very hard and can play a load bearing and hinder theovement of the plastic deformation of the matrix dislocations. The interface betweenhe SiC particles and the matrix of the hybrid reinforced composites are very stability...