The service temperature of commercial Ti-6Al-4V alloy usually does not exceed 400 ℃. In this work, Ti-8Al-4V-1Nb-xB (wt%) alloy was designed based on Ti-6Al-4V by the Calphad method to improve the properties at high temperatures at a low cost. Compared to Ti-6Al-4V, the strength and elongation of Ti-8Al-4V-1Nb-0.1B increased by 20 % and 75 %, respectively. The Ti-8Al-4V-1Nb-0.28B achieved excellent strength 560±21 MPa and elongation 25.7±1.4 % at 550 ℃. The fracture of Ti-8Al-4V changed from intergranular to the combination of intergranular and transgranular with the addition of B. The solid solution strengthening of Al, the grain boundary α reinforced by TiB particles, and the increase in density of α/β interfaces and α/α high-angle grain boundaries accounted for the improvement of strength. The oxidation resistance was significantly improved because of the addition of Al and Nb elements. This work provided a new idea to enhance mechanical properties at high temperatures and increased the service temperature of Ti-Al-V by alloying and microstructure design at a low cost.

中文翻译：

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新型铸态α+β Ti-8Al-4V-1Nb-xB合金在550 ℃下具有优异的强度和延伸率


商业Ti-6Al-4V合金的使用温度通常不超过400℃。本工作以Ti-6Al-4V为基础，采用Calphad方法设计了Ti-8Al-4V-1Nb-xB（wt%）合金，以低成本改善高温性能。与Ti-6Al-4V相比，Ti-8Al-4V-1Nb-0.1B的强度和延伸率分别提高了20%和75%。 Ti-8Al-4V-1Nb-0.28B在550℃时获得了优异的强度560±21 MPa和伸长率25.7±1.4%。 B的添加使Ti-8Al-4V的断裂由沿晶断裂转变为沿晶与穿晶相结合的断裂形式。Al的固溶强化、TiB颗粒强化晶界α、α/β界面密度增加α/α大角度晶界有助于强度的提高。由于Al、Nb元素的添加，抗氧化性能显着提高。该工作为提高Ti-Al-V材料的高温力学性能、通过合金化和组织设计以低成本提高其使用温度提供了新的思路。