Study On Al₂O₃ Particle And Short Fibre Hybrid Ceram/ Casting Aluminum Alloy Composite

To prepare prefabricate piece by using Al2O3 ceramic grain and short fiber which distributed as three dimensional- net structure in the material that would decompose in high temperature, then to make the molten metal of ZL109 infiltrate into the void of prefabricate piece and freeze through the method of extruding, and last the Al2O3 ceramic grain and short fiber hybrid reinforced aluminum matrix composite material is prepared by this way, the composite was densification and the distribution of reinforcing phase was uniform in the matrix .Further studied on the mechanical property of composite and the influence of cryogenic treatment on microstructure and property of composite. the cryogenic treatment could promoted the Si phase to precipitate between the aging process, the dimension,numerical measure and distribution of Si phase related to the cryogenic treatment process directly; the precipitation of Si phase made the lattice parameter reduce and the crystal face was preferred orientated, all these were approved by XRD and TEM . The mechanical property and wear property of composite were tested and analysis , the result show that ,cryogenic treatment could increase the strength of composite, and decrease the hardness of composite on the surface which normal to extruded orientation , and opposite on the surface which parallel to the extruded orientation ; The wear property of composite was better than matrix alloy ,and corresponded with HT250 ,the wear rate increased as the contact pressure grew ,and decreased as the speed grew ,the friction was less than matrix alloy on the stage of stable wear .The wear property of cryogenic treated composite material was better than un-cryogenic treated . The wear mechanism was that the shear tearing caused by sticking wear as well as the forming and expanding of crack in view of brittleness of secondary surface layer.