Optimizing strength and fatigue crack propagation resistance of in-situ TiB2/Al-Cu-Mg composite sheet

Abstract

The industrial-grade TiB2/Al-Cu-Mg composite sheet was fabricated via casting and rolling methods. Cold-rolling coupled with low-temperature aging treatment was used to regulate the grain size, dislocation density, precipitates and TiB2 particle distribution, to optimize the strength and fatigue crack propagation (FCP) resistance of the sheet. The results show that pre-rolling deformation combined with low-temperature long-term aging is beneficial for obtaining fine grains, high-density dislocations, high-density nano precipitates and uniform particle distribution, all of which are conducive to improving strength. The TiB2/Al-Cu-Mg composite sheet can achieve remarkable ultimate tensile strength over 600 MPa regardless of its excellent elongation (12 %). Furthermore, uniformly distributed TiB2 particles and high-density nano precipitates are beneficial for offsetting the negative effect of high-density dislocations on FCP. Finally, the small pre-rolling deformation (5 %) combined with low-temperature long-term aging achieves excellent strength and FCP resistance combination.