Multi-heterostructure and mechanical properties of N-doped FeMnCoCr high entropy alloy

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

2 Scopus Citations
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Author(s)

  • Zhufeng He
  • Nan Jia
  • Haile Yan
  • Yongfeng Shen
  • Mingwei Zhu
  • Xianjun Guan
  • Xiaoli Zhao
  • Shenbao Jin
  • Gang Sha

Detail(s)

Original languageEnglish
Article number102965
Journal / PublicationInternational Journal of Plasticity
Volume139
Online published19 Feb 2021
Publication statusPublished - Apr 2021

Abstract

High-entropy alloys (HEAs) have been extensively studied in recent years. However, yield strength of HEAs in which austenite is the dominating phase is usually low, far from satisfying the engineering demands. Improving performance-cost ratio of such alloys will help for their practical structural applications. Here we report a novel strategy to produce ultrastrong, tough, and low-cost HEAs, in which heavy nitrogen-doping (2.6 at.%) was applied to an inexpensive metastable FeMnCoCr HEA. Coupled with simple thermomechanical processing, we produced a multi-heterostructure, which consisted of fine α-martensite laths, deformed austenite with dense dislocations, recrystallized ultrafine grains and nano-nitride precipitates. Our novel FeMnCoCrN HEA exhibits a high yield strength of 1310 MPa which is ~5.2 times stronger than its base alloy without nitrogen doping. In particular, the highly dislocated body-centered cubic (bcc) martensite laths formed in the austenitic deformation matrix has an unexpected area fraction up to 24%. The hetero-deformation induced strengthening then reaches 750 MPa at the yield point, leading to a remarkable yield strength elevation of the material. Moreover, the high nitrogen content changes the dominant deformation mechanism from martensitic transformation to twinning, which contributes to a satisfactory uniform elongation of 16.5%, while the material is further strengthened by the dynamically refined microstructure. The high-nitrogen duplex alloy design strategy developed here provides a new paradigm for developing high-performance fcc HEAs.

Research Area(s)

  • Ductility, Heterostructure, High entropy alloy, Strengthening

Citation Format(s)

Multi-heterostructure and mechanical properties of N-doped FeMnCoCr high entropy alloy. / He, Zhufeng; Jia, Nan; Yan, Haile; Shen, Yongfeng; Zhu, Mingwei; Guan, Xianjun; Zhao, Xiaoli; Jin, Shenbao; Sha, Gang; Zhu, Yuntian; Liu, Chain T.

In: International Journal of Plasticity, Vol. 139, 102965, 04.2021.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review