Influence mechanism of grain boundary α phase configuration on the strength and toughness of TC18 near-β titanium alloy
FAN Jingxian1, LIU Chaoqiang1, ZHAN Xiaodong2, YANG Xiuye1, GE Jinyang1,3
1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. Hunan Xiangtou Goldsky Titanium Industry Technology Co., Ltd, Changde 415001, China; 3. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
Abstract：Near-β titanium alloys, owing to their outstanding strength and toughness, have become key structural materials in aerospace applications. However, achieving the synergistic coordination of strength, plasticity, and toughness remains a critical challenge. This study focuses on lamellar structured TC18 near-β titanium alloy. By employing two different processes, namely dual annealing and forging combined with dual annealing, alloys with distinct grain boundary α configurations (C-GB and D-GB) were prepared. The aim is to investigate the influence mechanism of grain boundary α configuration on the strength and toughness of the alloy. The results indicate that the content and size of primary α phase within the grains are similar in both C-GB and D-GB alloys. The main difference lies in the distribution of the grain boundary α phase, which is continuous in the C-GB alloy, while it exhibits a discontinuous distribution in the D-GB alloy. The grain boundary α configuration has a minor effect on the tensile strength of the alloy, the tensite strength of D-GB alloy (1 052.8 MPa) is approximately 6.7% higher than that of the C-GB alloy (986.3 MPa). However, it plays a decisive role in plasticity and fracture toughness. The elongation and fracture toughness of the D-GB alloy (12% and 91.5 MPa·m1/2) are significantly higher than those of the C-GB alloy (3% and 76.7 MPa·m1/2). In the C-GB alloy, the continuous grain boundary α phase acts as a preferential pathway for crack initiation and propagation. In contrast, in the D-GB alloy, the discontinuous grain boundary α phase and the randomly oriented α lamellae prevent local dislocation pile-up, leading to more uniform plastic deformation, then effectively inhibiting void nucleation and crack propagation. This study provides insights for designing titanium alloys with both high strength and high damage tolerance.
范静娴, 刘超强, 詹孝东, 杨秀烨, 盖晋阳. 晶界α相构型对TC18近β钛合金强韧性的影响机制[J]. 粉末冶金材料科学与工程, 2026, 31(2): 188-198.
FAN Jingxian, LIU Chaoqiang, ZHAN Xiaodong, YANG Xiuye, GE Jinyang. Influence mechanism of grain boundary α phase configuration on the strength and toughness of TC18 near-β titanium alloy. Materials Science and Engineering of Powder Metallurgy, 2026, 31(2): 188-198.
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2026, Vol. 31 
