(B4c+Al2o3)/Al Composites with Excellent High Temperature Strength and Thermal Stability Prepared by Sintering in Air Atmosphere

Abstract

B4C/Al composites are commonly used as neutron absorption materials. The introduction of amorphous Al2O3 through surface oxidation of Al powder can significantly enhance the mechanical properties of the composites; however, the thermal stability of the composite is compromised due to the inherent instability of amorphous Al2O3. In this study, (B4C+Al2O3)/Al composites were sintered in an air atmosphere for the first time, generating stable γ-Al2O3. It was found that in comparison with the conventional vacuum sintering process, (B4C+Al2O3)/Al sintered in an air atmosphere exhibited increases in ultimate tensile strength of 42% at room temperature and 88% at 350 °C. Furthermore, due to the reaction between Al and oxygen, the composite exhibited exceptional thermal stability when subjected to annealing at 620 °C, demonstrating an ultimate tensile strength of 144 MPa at 350 °C, surpassing values reported in other studies.

Keywords: Al matrix composites, neutron absorbing materials, (B4C+Al2O3)/Al composites, powder metallurgy, air atmosphere