The Research Of Fabrication And Performance In-situ MgO Reinforced Magneisum Matrix Composites

In this paper, MgO/Mg composite materials was prepared in situ method, which overcomes the problem of particle reinforced magnesium-based composite materials interface conjunction and pollution.The reinforced particle of MgO in-situ and alloying elements improve effectively in the material of performance. Conventional hot sintering process and current heating hot press sintering process were studied systematically in order to manufacture in situ MgO particle reinforced magnesium matrix composite.And then mechanical properties such as density, Vickers hardness and impact toughness were measured to evaluate the optimal process parameters.The microstructure, fracture surfaces and phase compositionof the in situ MgO/Mg composites were also studied using SEM, EDS and XRD technologies to interpret the test results.Dynamic kinetics model of self-assembly growth of in-situ reinforcements is prposed in this paper.In this study, the Gibbs free energy was calculated in situ reaction of Mg-Al2O3, Mg-CuO and Mg-MnO2. Ball milling mixture of Mg powder+Al2O3 powder, Mg powder+CuO powder and Mg powder+MnO2 powder were done DSC analysis to determine the temperature of the reaction:Mg-Al2O3 occurred reaction in the 325℃,Mg-CuO in the 310℃around, Mg-MnO2 in about 320℃.Under the pressure of 300 Mp, ball milling ingredients were shaped into pressed compact by chill-pressing. These pressed compacts were sintered in the tube type resistance furnace which companied with home-made protective device in a high-purity Ar atmosphere.The affection of the material properties were talked about by the sintering time and sintering temperature. And then the sintered samples were hot-pressed using current heating hot press sintering process.The results show that the sintering temperature and sintering time have a certain influence to the material properties.Through the study on the effect of the material properties by the different sintering temperature,550℃was to be determined the best sintering temperature of sample 1,580℃for the best sintering tmperature of sample 2.With the sintering time prolonging, the material properties were improved, but not very clearly. The pressed compacts were manufactured in conventional hot sinter process to improve its electrical conductivity, for the current heating hot press sintering process to create conditions for the smooth going. The material performances were enhanced by the current heating hot press sintering. Vichers hardness test shows that the Vichers hardness number of hot press sintering sample is higher. After the current heating hot press sintering, the continuous distribution of second phase was improved in the grain boundary of magnesium matrix. The MnO2 reacted with magnesium-based producting Mn and MgO in-situ. Mn could enhance the material toughness. Al2O3 and CuO reacted with magnesium-based producting Al, Cu and MgO in-situ and formation of crystals with magnesium-based. MgO could enhance the hardness of the material, but the toughness of the material had little increase. Through SEM, EDS and XRD analysis to interpret the test results, the dynamic kinetics model of self-assembly growth of in-situ reinforcements is proposed initially in this paper. The Strengthening Mechanism of in-situ MgO reinforced magneisum matrix composites was to discuss.