Effect of nitrogen on microstructure and mechanical properties of CrMnFeVTi6 high entropy alloy
(1. Bgrimm MTC Technology Co., Ltd., Beijing 102628, China;
2. Beijing System Design Institute of Electro Mechanic Engineering, Beijing 100854, China;
3. The Fourth Academy of CASIC, Beijing 100028, China)
2. Beijing System Design Institute of Electro Mechanic Engineering, Beijing 100854, China;
3. The Fourth Academy of CASIC, Beijing 100028, China)
Abstract: In order to evaluate interstitial strengthening effect on the properties of high entropy alloy (HEA), a nitrogen-doped CrMnFeVTi6 HEA was fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). XRD, SEM, TEM and FIB were used to characterize the phase composition and microstructure of this material. The sintered bulk HEA exhibits a microstructure comprising TiNx, BCC, Laves and B2 phases. The HEA exhibits high yield strength (>2729 MPa) and hardness in lower temperature range of <380 °C. Quantitative calculations of the contributions from each strengthening mechanism in the BCC phase indicate that the interstitial strengthening by nitrogen is the dominant mechanism. Nitrogen additions in the BCC phase can produce a yield strength increase of ~634 MPa/at.%, which is much higher than the strengthening effects of carbon or boron additions in other alloys. This demonstrates that adding nitrogen is a viable approach for enhancing the strength of HEAs.
Key words: high entropy alloy; nitrogen element; mechanical properties; interstitial strengthening