Chen Po-Sung, Kuo Bao-Teng, Tsai Pei-Hua, Jang Jason Shian-Ching, Chen Chih-Yen, Tsao I-Yu
Institute of Materials Science and Engineering, National Central University, Taoyuan 320, Taiwan.
Department of Mechanical Engineering, National Central University, Taoyuan 320, Taiwan.
Materials (Basel). 2025 May 11;18(10):2219. doi: 10.3390/ma18102219.
Because of their low density and excellent material properties, lightweight Ti-rich medium-entropy alloys (MEAs) have great potential for application in the aerospace and automotive industries. This study investigated the effects of B doping on the microstructure and mechanical properties of a (Ti(AlCrNbV))B alloy series. The mechanical properties of the alloys were then enhanced through thermomechanical treatment, and the strengthening mechanism was explored by characterizing the alloys' microstructure and mechanical properties. X-ray diffraction revealed that the (Ti(AlCrNbV))B alloys retained their body-centered cubic structure. However, the addition of B resulted in a rightward shift in the diffraction peaks due to B having a smaller atomic radius compared with the other constituent elements. Weak diffraction peaks corresponding to TiB were discovered in the diffraction patterns for the alloys with 0.4 or 0.6% B content (named B0.4 and B0.6, respectively). The hardness of the homogenized alloys was increased from 321 Hv for the base alloy (B0) to 378 Hv for B0.6. In tensile testing, the homogenized alloy with 0.2% B content (B0.2) exhibited a yield strength of 1054 MPa and 21% elongation, which represented 17% greater strength compared with B0. Conversely, the mechanical properties of B0.4 and B0.6 were poorer due to precipitation at grain boundaries. After thermomechanical treatment, the alloys' strength and hardness increased with increasing B content despite various heat treatment conditions. The recrystallization behavior of the alloys tended to be delayed by B doping, resulting in an increase in the recrystallization temperature. After recrystallization at 900 °C, the elongation of B0, B0.1, and B0.2 exceeded 20%. Of the (Ti(AlCrNbV))B alloys in the series, B0.2 presents the optimal combination of favorable yield strength and ductility (1275 MPa and 10%, respectively).
由于其低密度和优异的材料性能，轻质富钛中熵合金（MEA）在航空航天和汽车工业中具有巨大的应用潜力。本研究调查了B掺杂对（Ti(AlCrNbV))B合金系列微观结构和力学性能的影响。然后通过热机械处理提高合金的力学性能，并通过表征合金的微观结构和力学性能来探索强化机制。X射线衍射表明，（Ti(AlCrNbV))B合金保留了其体心立方结构。然而，由于B的原子半径比其他组成元素小，B的添加导致衍射峰向右移动。在含0.4%或0.6%B的合金（分别命名为B0.4和B0.6）的衍射图谱中发现了与TiB对应的弱衍射峰。均匀化合金的硬度从基础合金（B0）的321 Hv提高到B0.6的378 Hv。在拉伸试验中，含0.2%B的均匀化合金（B0.2）的屈服强度为1054 MPa，伸长率为21%，与B0相比，强度提高了17%。相反，由于晶界处的析出，B0.4和B0.6的力学性能较差。热机械处理后，尽管热处理条件不同，但合金的强度和硬度随B含量的增加而增加。B掺杂倾向于延迟合金的再结晶行为，导致再结晶温度升高。在900℃再结晶后，B0、B0.1和B0.2的伸长率超过20%。在该系列的（Ti(AlCrNbV))B合金中，B0.2具有良好的屈服强度和延展性（分别为1275 MPa和10%）的最佳组合。
