Tuning the microstructure and strengthening mechanism of the CoCrFeNi high-entropy alloy via doping metalloid and interstitial elements
JOURNAL OF ALLOYS AND COMPOUNDS(2023)
摘要
The synergistic strengthening and toughening of metalloid and interstitial elements were demonstrated for the first time in the CoCrFeNi high-entropy alloy (HEA) by the sequential addition of Si, B, and N elements. The addition of Si simultaneously enhances the strength and ductility of the CoCrFeNi HEA, further, the doping of B promotes the formation of Cr2B precipitates and the grain refinement, and the addition of N further refines the grain size and increases the lattice distortion and the degree of chemical short-range order (SRO). The strengthening effect to yield strength of the addition of Si, B, and N elements is well described by the strengthening model. Doping Si, B, and N elements can regulate the stacking fault energy (SFE), lattice distortion, and short-range order of the alloy, and consequently induce the multiple twins and nanoscale transformation from the face-centered cubic (FCC) to the hexagonal close-packed (HCP) phase upon room-temperature tension, which enhances the work-hardening capability of the alloy. Finally, a dual heterostructure of grain size and precipitate phase distribution is formed in CCFN-Si-B-N-70 0 HEA by regulating heat treatment. The yield strength of the current alloy is further enhanced up to 1.2 GPa, and the ductility is maintained at 13 %. This study not only provides new insights into the strengthening and toughening mechanism of metalloid and interstitial elements but also a new paradigm for the development of HEAs with excellent strength-ductility synergy.(c) 2023 Elsevier B.V. All rights reserved.
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关键词
Synergistic strengthening and toughening,High-entropy alloy,Metalloid and interstitial elements,Strengthening model,Chemical short-range order (SRO)
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