Strength–ductility trade-off in TiB-TC4 composites with a pseudo core–shell structure
Yuanhao Sun, Zhixi Zhu, Qiang Wang, Xiaotong Jia, Wenjun Li, Zhaohui Zhang, Xingwang Cheng
Abstract
Heterogeneous structure is practical to improve the strain hardening abilities of materials due to the effect of hetero-deformation induced hardening, especially of composites. In this study, a series of TiB/TC4 composites with a pseudo core–shell structure of bimodal grain distribution were fabricated via a two-step ball-milling and spark plasma sintering. The synthesized TiB/TC4 composites have a structure of coarse lamella α-Ti grains of average 23.6 μm in diameter surrounded by fine α-Ti lamella grains of average 4.2 μm, with TiB distributed on the primary TC4 surface areas. TiB/TC4 composites with 0.4 wt% TiB2 exhibited the best comprehensive mechanical properties with an ultimate tensile strength of 1161.95 MPa (a 35.1% increase compared with that of pure TC4) and an elongation of 7.57%. In conclusion, the pseudo core–shell structure improved the strength by improving the strain-hardening abilities, achieved by the coordinated deformation between coarse grains and fine grains.