Microstructure and mechanical property evolution of in-situ ZrB2/AA7085 nanocomposites during hot rolling

The introduction of dispersed nanoparticle is considered to be an ideal strategy to achieve high strength and ductility of metals and alloys. In this work, the ZrB2/AA7085 nanocomposites were synthesized via the Al-K2ZrF6-KBF4 in-situ melt reaction system, and the microstructure and mechanical property evolution of the nanocomposites were further investigated. The average size of ZrB2 nanoparticles is 95 nm, and the agglomeration distribution of reinforced particles is modified by huge rolling force. With increasing rolling reduction, the refinement degree of alpha-Al grains increases, since the introduced ZrB2 particles promote the dynamic recrystal-lization (DRX) by causing dislocation pile-up. Precipitation behavior is accelerated by misfit dislocations presenting at the semi-coherent interface of ZrB2 and Al. The ultimate tensile strength and elongation of nanocomposites with 80% deformation are 649.7 MPa and 12.24%, increased by 7.64% and 28.71% compared to the matrix alloy. The strength increment is ascribed to optimized distribution of ZrB2 reinforced particles and equiaxed recrystallized grains. The improved ductility is attributed to the increased randomness of crack propagation path induced by ZrB2 nanoparticles. Thus, this work aims to provide a fundamental insight into the high strength and ductility nanocomposites developed by hot rolling.