Effects of in situ generated ZrB_2 nano-particles on microstructure and tensile properties of 2024A1 matrix composites

摘要

The main purpose of this paper is to investigate the effects of nano-size ZrB_2 particles on the microstructure and tensile properties of 2024A1 matrix composites. The microstructure and tensile properties of the 2024A1 matrix composites reinforced by ZrB_2 nano-particles fabricated from 2024Al-K_2ZrF_6-KBF_4 system by direct melt reaction are investigated by XRD, OM, SEM, EDS, TEM and tensile testing. The results reveal that the ZrB_2 nano-particles exhibit rectangular and nearly hexagon shape with the size ranging from 30 to 100 nm, and the reasonable uniform distribution of ZrB_2 nano-particles gives rise to significant grain refinement of 2024A1 alloy. Tensile testing results show that the tensile strength and yield stress of the composites increase continuously. However, the elongation of the composites increases almost linearly and declines later as the increasing of ZrB_2 content. The fracture morphologies are in accord with corresponding ductility results. What's more, the strengthening mechanism of ZrB_2 nano-particles is established.