Elevated temperature properties of Mg-12Li-Al-MgO composites
(Department of Materials Science and Engineering, Xihua University, Chengdu 610039, China)
Abstract: The compressive creep of Mg-12Li-Al-MgO particulate composites was investigated, which were produced by the reaction of reinforcement materials (B2O3) with Mg-12Li-Al alloy melt in the temperature range of 100−190 ℃ and under different compressive stress in the range of 40−70 MPa with special apparatus. The content of MgO particulates is about 0, 5%, 10%, 15%(volume fraction) in Mg-12Li-Al alloy respectively. The results reveal that the creep resistance of the particulate composites is increased with increasing the content of MgO particulates and considerable improvement in creep resistance is observed in Mg-12Li-Al-MgO composites. However, over all range of temperatures and stresses, the creep data for these composites can be correlated using an empirical equation ＝Aσnexp(−Q/RT), where n is 4.93 and Q is about 78.1 kJ/mol for Mg-14Li-Al alloy and n is between 7.48 and 9.47 and Q is 111.2−137.3 kJ/mol for Mg-12Li-Al-MgO composites. The different compressive creep behavior of the composites is associated with the different material constant A. The compressive creep rate is controlled by the lattice diffusion of Li and dislocation climb.
Key words: Mg-12Li-Al alloy; MgO particulates; B2O3; microstructure; compressive creep behavior