Fabrication of Al-YOF/TiB2 composites by molten-salt-assisted stirring casting

Abstract

The poor wettability between oxides and Al melt and presence of alumina film on Al melt surface seriously limits the fabrication of Al matrix composites (AMCs) reinforced by oxides via casting method. The wettability of oxides can be improved by modification with fluorine, and the oxyfluoride is more feasible to incorporate into Al melt, but the strength of the oxides may decrease after modification. Therefore, it is necessary to assess the strengthening effect of oxyfluoride by comparison with classical reinforcement. In this work, AMCs reinforced with yttrium oxyfluoride (YOF) and TiB2 were successfully fabricated by molten-salt-assisted stirring casting. YOF particles exhibit a better distribution in Al matrix than TiB2 particles, and the YOF particles show better bonding strength with Al matrix than TiB2 due to reactive wetting. Al-YOF composite shows higher hardness, tensile strength, and ductility than Al-TiB2 composite. The values of microhardness, yield strength (σ0.2) and ultimate tensile strength (σb) of Al-YOF composite are 27.2 HV, 55 MPa and 81 MPa, which are 25.9 %, 62 % and 53 % higher than that of pure Al.