Study on the reaction mechanism of Al-ZrO2-B4C system

The composite (alpha-Al2O3+ZrC+ZrB2)/Al has been fabricated by using exothermic dispersion synthesis. When the reinforcement volume fraction is 100%, there are two exothermic peaks occurred in DSC curve of the Al-ZrO2 system. But when the reinforcement volume fraction is 30%, there is only one exothermic peak occurred in the DSC curve and the height of it decreases. When the molar ratio of B4C/ZrO2 is 0, the reaction products are consisted of alpha-Al2O3 grains and Al3Zr blocks. With an increase in the molar ratio of B4C/ZrO2, the amount of the Al3Zr decreases and the phases of ZrB2 and ZrC are formed. When the molar ratio of B4C/ZrO2 increases to 1/3, the Al3Zr almost disappear and the reinforcements of the composites are composed of alpha-Al2O3, ZrC and ZrB2. The corresponding XRD (X-ray diffraction) patterns also testify this.