Effect Of Rare Earth On Microstructure And Mechanical Properties Of Particulate Reinforced Aluminum Matrix Composites

Particulate reinforced aluminum matrix composites are proverbially used inautomotive industry, aviation and aerospace, electron, war industry and physical culturedue to their low density, high specific strength, high specific stiffness, low coefficient ofthermal expansion, favourable thermostability, heat conduction, and wear-resistingproperty. However, particulate reinforced aluminum matrix composites are usually usedin high temperature; so, it will be of great importance to study how to prevent compositelosing its efficacy and how to improve its high temperature strength.Influences of different content of rare earth Ce, Mg, and Al₂O₃particles onmicrostructure of Al₂O₃p/Al composites were studied by Axiovert25CA metallographicmicroscope, and QUANTA400scanning electron microscope. Moreover, Influences ofdifferent content of rare earth Ce, Al₂O₃, SiC particles and hot deformation parameterson hot-deformation behavior of Al₂O₃p/Al and SiCp/Al composites were also studied byGleeble-1500D thermal simulator.The results show that rare earth Ce can promote dispersion of Al₂O₃and SiC, refine α-Al grains, and change the morphology of AlFeSi compounds from thick bone shape intointermittent bulk or globular shape. Mg is apt to gather on the surface of Al₂O₃particles,which improves the wettability between Al₂O₃and aluminum matrix. When the contentof Mg less than2%, α-Al grains are refined remarkably. When the content of Mg reaches3%,α-Al grains begin to coarsing.When the content of Mg beyond3%, Al-Fe compoundsappears and presents needle strip morphology, and it is coarsing with the increasing of Mg.Al₂O₃, SiC particles and rare earth Ce can greatly enhance the flow stress and hightemperature strength of the composites, which leads to a reinforcement to it. Rare earthCe can restrain the dynamic recrystallization of the SiCp/Al composites. Hot compressioncan promote fragmentation and dispersion of SiC particles, which makes SiC particles havestreamline dispersion along with extrusion direction. However, it will appear abhesion andfracture of SiC particles at low temperature and high strain rate.