Diffusion bonding of high entropy alloy and stainless steel at a relative lower temperature via surface nano-crystallization treatment

HT Gao and GQ He and Q Li and YE Li and W Hu and SJ Zhou and FM Liu and JL Yi and YP Zhang and ZH Cai and S Ogata and LJ Qiao and L Gao, JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, 24, 475-487 (2023).

DOI: 10.1016/j.jmrt.2023.03.026

Sluggish diffusion effect of high entropy alloy limits its diffusion bonding with other components in practical applications. In this paper, the surface mechanical attrition treatment (SMAT) strategy for performing diffusion bonding joints of high entropy alloy (HEA) at a relative lower temperature is proposed. The EDS results demonstrate that the diffusion distance of Fe atoms increases significantly after SMAT since more gain boundaries are formed after SMAT. Furthermore, with this method the HEA/stainless steel joint can achieve a useable strength of 320 MPa at relative lower temperature of 850 degrees C (similar to 0.63 Tm, Temperature of melting). Molecular dynamics simulations show that the apparent diffusivity of Fe in the polycrystalline model is significantly higher than in the single-crystalline model because of fast diffusion at grain boundaries, i.e., the grain boundaries are fast diffusion channels. More detailed microstructure analysis indicates that although the density of dislocations increases after SMAT, its elemental diffusion ability is much weaker compared with grain boundaries. This study provides a feasible avenue for the application of diffusion bonding in HEAs, which could greatly broaden the applications fields of HEAs. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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