Abstract
To enhance the mechanical properties of Mg alloys, 0-30vol% Al_2O_3/Mg powders were formed by ball milling powder mixtures of pure Mg and Al_2O_3 particles, and then Spark plasma sintering (SPS) compacts (Al_2O_3/Mg discs) were made by the Al_2O_3/Mg powders The effect of the cooling conditions in the SPS process on the mechanical properties of the Al_2O_3/Mg discs was investigated From the results of SEM, XRD and TEM-EDS, the microstructures of the Al_2O_3/Mg discs were identified to consist of a- Mg solid solution, Al_2O_3 particles, refined MgO particles and refined needle-like Mg_<17>Al_<12> ( more than 20vol% Al_2O_3 content) The mechanical properties of the discs were able to control by the regulation of the cooling conditions (cooling rate (v_c) and applied pressure in the cooling (p_c)) in SPS process, and as a result, the SPS discs possessing the mechanical properties beyond HP compacts were obtained under the cooling conditions of "vc= 0.83K/s and pc= 20MPa" Main factor that the cooling conditions in SPS process effect on the mechanical properties of the Al_2O_3/Mg discs are considered to be the compresive residual stress generated in the α - Mg solid solution by the thermal stress associated with deference of the coefficients of thermal expansion between the α - Mg and ceramics particles (Al_2O_3 and MgO) in the discs
