Achieving refined microstructure and enhanced mechanical properties in a Ti-46Al-5Nb-0.1C alloy via in-situ co-precipitation of multi-phase reinforcements
Weigang Yang, Dingbang Sun, Yongfeng Liang, Mingao Li, Wenjing Li, Junpin Lin
Abstract
A novel TiAl composite with multi-phase reinforcements has been successfully prepared by combination of plasma rotating electrode process, low-energy ball milling and induction hot-press sintering in the present study. The introduction of multi-phase reinforcements significantly refined the lamellar colonies and enhanced the mechanical properties of TiAl composites. With the addition of B 4 C, nano TiB, nano Ti 2 AlC, and TiB whiskers precipitated at the boundaries of lamellar colonies, collectively forming a network-like reinforcement structure. Meanwhile, the mean grain size of (α 2 + γ) lamellar colonies decreased significantly from 425.3 μm to 78.5 μm with 0.1 wt% B 4 C addition. In addition, TiAl composites with 0.05 wt% and 0.1 wt% B 4 C achieved UTS and elongation of 637.68 ± 29.13 MPa/0.24 ± 0.12 % and 659.85 ± 35.47 MPa/0.09 ± 0.05 % (room temperature), as well as 591.19 ± 27.95 MPa/1.76 ± 0.44 % and 553.85 ± 36.34 MPa/1.47 ± 0.39 % (800 °C), respectively. The addition of B 4 C refined the lamellar colonies, mitigated stress concentration, leading to a more homogeneous distribution of dislocations within the microstructure. Simultaneously, the introduction of multi-phase reinforcements in TiAl composites induced substantial nano twins during deformation, thereby effectively alleviating stress concentration and enhanced its plasticity.