Nitrogen-induced hardening in an austenitic CrFeMnNi high-entropy alloy (HEA)

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:804

Article

Traversier, Mathieu¹  Mestre-Rinn, Pierre¹  Peillon, Nathalie¹  Rigal, Emmanuel²  Boulnat, Xavier³  Tancret, Franck⁴  Dhers, Jean⁵  Fraczkiewicz, Anna¹ 

[1] Univ Lyon, MINES St Etienne, CNRS, UMR 5307 LGF,Ctr SMS, F-42023 St Etienne, France

[2] CEA LITEN, F-38054 Grenoble, France

[3] Univ Lyon, INSA Lyon, MATEIS UMR CNRS 5510, F-69621 Villeurbanne, France

[4] Univ Nantes, CNRS, Inst Mat Jean Rouxel, IMN, F-44000 Nantes, France

[5] Framatome France, Lyon, France

关键词: High entropy alloys (HEA);    Nitrogen alloying;    Solid solution;    Microstructure;    Tensile properties;   

DOI  :  10.1016/j.msea.2020.140725

来源: Elsevier

【 摘 要 】

Nitrogen is a well-known gamma-stabiliser in austenitic steels, also responsible for significant solid solution hardening of these materials. Yet, only few papers have studied its impact on austenitic high-entropy alloy (HEA) matrixes. This study focuses on a cobalt-free, non equimolar CrFeMnNi HEA doped with nitrogen. A series of alloys was cast under a nitriding atmosphere to promote nitrogen absorption into the liquid alloy. Study of as-cast alloys has shown nitrogen presence in solid solution up to 0.3 wt % (1.2 at. %). Over the whole range of compositions, a linear increase of hardness (134 HV/wt. % of N) was measured as well as an expansion of the lattice parameter of Delta a/a = 1.01/wt. % N due to nitrogen addition in the interstitial sites of the lattice. Tests on forged and annealed samples showed that the increase of hardness with nitrogen addition is higher than in as-cast state (210 HV/wt. % of N) surely due to presence of other strengthening mechanisms. Tensile tests confirmed that the presence of dissolved nitrogen increases yield strength and ultimate strength and enhances strain-hardening, without any modification of ductility.

【 授权许可】

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