High cycle fatigue behavior of in-situ ZrB2/AA6111 composites.

In this work, the in-situ ZrB 2 /AA6111 composites with different particle volume fractions were prepared by direct melt reaction method and followed by hot extrusion deformation and T6 heat treatment. The microstructure characteristics, tensile and fatigue properties were carefully studied. The results showed that the addition of nano-ZrB 2 particles made ZrB 2 /AA6111 composites have finer grains and the ultimate tensile strength of composites increases with the increase of particle volume fraction. The ZrB 2 /AA6111 composites showed higher fatigue limits than the unreinforced alloy, and the composites with a particle volume fraction of 2 vol% have the highest fatigue limit of 125 MPa, which is a 31.5% increase compared to the unreinforced alloy. Through microstructure analysis, it is found that the fatigue limit was related to the volume fraction and distribution of ZrB 2 particles. The initial cracks of composite and unreinforced alloy were both caused by persistent slip bands and the crack propagation of the composites was more complex due to the resistance of reinforcing particles. [ABSTRACT FROM AUTHOR]