Abstract

In the dynamic theory of martensitic transformations, temperature M_s of the start of transformation corresponds to conditions that are optimal for generating waves by nonequilibrium d electrons that control the growth of a martensitic crystal. The recognition of relative damping \({{\Gamma}}_{{\text{e}}}^{'}\) of s electrons plays a substantial role in this case. A general analysis that has made it possible to propose, for the first time, an analytical formula for critical size D_c\(\left( {{{\Gamma}}_{{\text{e}}}^{'}} \right)\) of austenite grains is used to interpret the results for chromium–nickel steels, in which the transformation is initiated by strong magnetic fields. Under conditions of positive bulk magnetostriction, a magnetic field with intensity H lowers the chemical potential of electrons. As a result, the D_c(\({{\Gamma}}_{{\text{e}}}^{'},\) H) value decreases and austenite with a grain diameter of D, which was stabilized by condition D < D_c(\({{\Gamma}}_{{\text{e}}}^{'},\) 0) in the absence of a field, becomes destabilized, since inequality D > D_c(\({{\Gamma}}_{{\text{e}}}^{'},\)H) is fulfilled. The dynamic theory predicts a sharp increase in the D_c(\({{\Gamma}}_{{\text{e}}}^{'},\) 0) value at \({{\Gamma}}_{{\text{e}}}^{'}\) → 1. This is evidenced by value D_c\(\left( {{{\Gamma}}_{{\text{e}}}^{'}} \right)\) ≥ 1 mm for steel 67Kh2N22, which is three orders of magnitude larger than D_c(\({{\Gamma}}_{{\text{e}}}^{'},\) 0) ≈ 1 μm for the Fe–31Ni alloy. Other peculiarities of the effect of magnetic field on the martensitic transformation are also discussed.

中文翻译：

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奥氏体晶粒尺寸接近临界值的钢中强磁场对马氏体相变影响的动力学理论

摘要

在马氏体相变的动力学理论中，相变开始的温度M _s对应于通过控制马氏体晶体生长的非平衡d电子产生波的最佳条件。在这种情况下，s电子的相对阻尼\（{{\ Gamma}} _ {{\ text {e}}} {{}}）的识别起着重要的作用。首次提出临界尺寸D _c的解析公式的通用分析\（\ left（{{{\ Gamma}} _ {{\ text {e}}} ^ {'} } \正确的）\）奥氏体晶粒的变化被用来解释铬镍钢的结果，其中的转变是由强磁场引起的。在正体磁致伸缩的条件下，强度为H的磁场会降低电子的化学势。结果，D _c（\（{{\ Gamma}} _ {{\ text {e}} ^ {'}，\） H）H值降低，奥氏体的晶粒直径为D，通过条件D < D _c（\（{{\ Gamma}} _ {{\ text {e}} ^ {'}，\） 0）在不存在字段的情况下变得不稳定，因为不等式D > D _c（\（{{\ Gamma}} _ {{\ text {e}}} ^ {'}，\）H）已实现。动态理论预测在急剧增加d _Ç（ \（{{\伽玛}} _ {{\文本{E}}} ^ {'}，\） 0）在值\（{{\伽玛}} _ {{\ text {e}} ^ {'} \） →1.这由值D _c \（\ left（{{{\ Gamma}} _ {{\ text {e}}} ^ {' }} \ right）\）对于67Kh2N22钢，≥1 mm，比D _c（\（{{\ Gamma}} _ {{\ text {e}}} ^ {'}，\）大3个数量级。 0）对于Fe–31Ni合金，≈1μm。还讨论了磁场对马氏体相变的其他影响。