Enhanced aging kinetic of Al3BC/6061 Al composites and its micro-mechanism

Abstract In this work, the aging behavior of Al 3 BC/6061 Al composites was investigated and the impacts of Al 3 BC on the aging kinetic as well as its micro-mechanism were unveiled. It is found that the aging kinetic of the composites is considerably accelerated and the peak aging time at 175 °C comes down from 14 to 6 h. Both positive and negative impacts due to the incorporation of Al 3 BC on the aging kinetic of the composites were discussed. The high density dislocations can either act as the heterogeneous nucleation substrate or play as the diffusion path to expedite precipitation process, while the low vacancy concentration and solute segregation on the interface suppress the formation of GP zone and reduce the chemical driving force for precipitation, respectively. Obviously, the positive effects caused by the dislocation contribute more in the current work. Microstructure characterizations verify that needle-like β″ phase and lath Q′ phase precipitate in the matrix and are impacted by the Al 3 BC differently. In the area free of Al 3 BC particle, they distributed uniformly in the matrix. However, in the vicinity of Al 3 BC particles, the precipitation of β″ is inhibited for the low vacancy concentration and segregation of Mg, Si elements on the Al 3 BC/Al interface, while the precipitation of Q′ phase is accelerated for the preferred nucleation of Q′ phase on the dislocation.