The effect of nitrogen on the microstructure and mechanical behavior of several Co-free high entropy alloys (HEAs) from the CrFeMnNi family was studied. Alloy design approach, based on thermodynamic computations, was implemented to obtain alloys with a high chromium content, a high nitrogen solubility as well as good austenite stability. An optimisation was made to meet selected criteria which led to three compositions with different nickel contents (Cr₂₀Fe₄₀Mn₁₅Ni₂₅, Cr₂₀Fe₄₄Mn₁₅Ni₂₁, and Cr₂₀Fe₄₇Mn₁₅Ni₁₈) optimised for, respectively, 0.4, 0.5 and 0.6 wt.% N. Such optimised alloys were elaborated and compared with another Co-free HEA (Cr₁₄Fe₄₆Mn₁₇Ni₂₃) doped with 0.11 to 0.29 wt.% N. It was shown that up to 0.56 wt.% N could be dissolved in the matrixes in agreement with their computed high nitrogen solubility. The differences in chemical composition between the four studied matrixes did not lead to any change in behavior in presence of nitrogen: the lattice parameter expansion and mechanical resistances (yield strength and tensile strength) evolve linearly with nitrogen addition, up to at least 0.56 wt.%. Especially, a significant effect of nitrogen content on strain-hardening was observed and was attributed to the formation of nanotwins in nitrogen-rich alloys.

中文翻译：

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在新设计的无钴奥氏体高熵合金中增强应变硬化，具有优化的氮溶解度


研究了氮对 CrFeMnNi 家族几种无钴高熵合金 （HEA） 的微观结构和力学行为的影响。采用基于热力学计算的合金设计方法，获得具有高铬含量、高氮溶性以及良好奥氏体稳定性的合金。为了满足选定的标准，进行了优化，导致三种具有不同镍含量的成分（Cr₂₀Fe₄₀Mn₁₅Ni₂₅、Cr₂₀Fe₄₄Mn₁₅Ni₂₁ 和 Cr₂₀Fe₄₇Mn₁₅Ni₁₈）分别针对 0.4、0.5 和 0.6 wt.% N 进行了优化。对这种优化的合金进行了细制，并与另一种掺杂 0.11 至 0.29 wt.% N 的无钴高翘 （Cr₁₄Fe，₄₆Mn₁₇Ni₂₃） 进行了比较。结果表明，高达 0.56 wt.% 的 N 可以溶解在基质中，这与它们计算的高氮溶解度一致。在氮存在下，四种研究的基质之间的化学成分差异不会导致行为发生任何变化：晶格参数膨胀和机械阻力（屈服强度和拉伸强度）随氮的添加线性变化，最高可达至少 0.56 wt.%。特别是，观察到氮含量对应变硬化的显着影响，这归因于在富氮合金中形成纳米孪生。