High-strength NbMoTaX refractory high-entropy alloy with low stacking fault energy eutectic phase via laser additive manufacturing

• Published in: Materials & design Vol. 201; p. 109462
• Main Authors: Zhang, Hang, Zhao, Yizhen, Cai, Jianglong, Ji, Shaokun, Geng, Jiale, Sun, Xiaoyu, Li, Dichen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2021; Elsevier
• Subjects: Fracture resistant; High-entropy alloys; NbMoTa; Selective laser melting; Stacking fault energy; NbMoTa; High-entropy alloys; Stacking fault energy; Selective laser melting; Fracture resistant
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2021.109462

The high-entropy alloys (HEAs) exhibit outstanding high-temperature properties and promise in a wide range of applications, such as aviation, nuclear energy and other fields. However, the problems of formability and defect control limit the successful realization of HEAs. Herein, we newly developed NbMoTaTi0.5Ni0.5 HEA which renders a high room-temperature compressive strength of 2297 MPa and high-temperature (1000 °C) compressive strength of 651 MPa. Meanwhile we present that the addition of both Ni and Ti can suppress the crack formation and enhance the formability of NbMoTa HEA, prepared by selective laser melting (SLM), without compromising the mechanical performance. Actually, the fracture is suppressed by the transformation of microcracks due to grain boundaries with low stacking fault energy (SFE) which can greatly improve the formability of HEAs while ensuring its high-temperature performance. The current study shall serve as a guideline for the development of refractory high-entropy alloys via additive manufacturing, such as selective laser melting. [Display omitted] •The addition of TiNi elements effectively inhibited the cracks in NbMoTa alloy during SLM process.•The compression strength of NbMoTaTi0.5Ni0.5 HEA can up to 2297 MPa at room temperature and 651 MPa at 1000 °C.•The results of TEM analysis show that the main grain boundary phase of NbMoTaTi is αTi, and that of NbMoTaTi0.5Ni0.5 is Ni3Ta.•The crack suppression mechanism induced by low stacking fault energy phase is proposed, and verified by calculating stacking fault energy (αTi, 471.4 mJ/m2, Ni3Ta 357.1 mJ/m2).