Influence of TiB 2 particles on aging behavior of in-situ TiB 2 /Al-4.5Cu composites

In this paper, the aging process of in-situ TiB2/Al-4.5Cu composites has been investigated carefully, especially the precipitation behavior in the presence of TiB2 particles. The mechanism of this particle-assisted precipitation in the composites are also studied systemically. Comparisons of the aging behavior between composites and matrix alloy have been made to investigate the effect of TiB2 particles. Moreover, attention has also been paid to tensile properties and hardness of TiB2/Al-4.5Cu composites and matrix alloy during aging procedure. Results indicate that TiB2 particles accelerate the aging processes and also induce inhomogeneous distribution of Al2Cu precipitates due to the high-density dislocations adjacent to particles. Besides, a rare phenomenon was found that the evolution on mechanical properties of the composites can be divided into two stages and this evolution is in good accordance with the evolution of the Al2Cu precipitates. Moreover, the time to peak-aged condition of the composites in mechanical properties comes down from 20 h to 8 h.