Comparative study of Li and Mg addition on the thermal behavior of the A1 based alloy powders

摘要

A1-3Li and Al-6Mg alloy powders were prepared through close-coupled gas atomization (CCGA), and their thermal reactivities were investigated. The two alloy powders and their oxidation products were analyzed by X-ray powder diffraction (XRD) and SEM/EDS. The thermal oxidation behavior of the two alloy powders were examined using the simultaneous TG-DTA technique in O_2 up to 1300°C. The results indicated that oxidation behaviors of the two alloys were significantly different. For A1-3Li powder, the oxidation proceeds in only one step and was complete, while the oxidation of Al-6Mg powder was stepwise and incomplete. For the unique oxidation step of A1-3Li alloy, the apparent activation energy was 339.7 kJ/mol and the frequency factor was much larger than that of Al-6Mg alloy, while the total apparent activation energy of A1-6Mg two-step oxidation was 404.9 kJ/mol. Furthermore, A1-3Li alloy exhibited a sharper exothermic peak, a lower violent reaction temperature and a larger oxidation reaction rate. The reasons for the different oxidation behaviors of the two alloys were analyzed.