Abstract: The thermodynamic behavior of CuO, Cu2O and MgO was analyzed at the low-temperature or at the high-temperature in self-propagating reactions of thermit respectively. The results show that CuO was more stable than Cu2O at the normal temperature, but it was in the contrary at high temperature; in addition, at low temperature, magnesium was more active than aluminum, but at high temperature aluminum can replace magnesium from magnesium oxide. By adding MgO to CuO+Al thermite, oxygen was supplied by the decomposition of CuO in the initial phase of the reaction, however oxygen was supplied responsively by the decomposition of Cu2O and MgO in the high temperature phase, which formed a different oxygen-supplied and complex combustion system at different temperature. In this combustion system, MgO absorbed the heat at high temperature by reduction reaction and released the heat at lower temperature by oxidation reaction. The heat of thermal peak was cut and moved to the late reaction stage, so thermit heat was averaged in the whole combustion process and the controlling strategies about the heat released by thermit was realized. The experiment results show that this complex oxygen supplied system had a significant effect on the self-propagating thermite reaction. The thermite had an advantage of stable combustion, high heat without explosion, beautiful forming, and fewer defects and so on.

Key words: Complex oxygen-supply, Heat balance, Self-propagating high-temperature synthesis, Thermit