In order to investigate the thermodynamic driving force for the experimentally observed accumulation of C in ferritic layers of severely plastically deformed pearlitic wires, the stabilities of C interstitials in ferrite and of C vacancies in cementite are investigated as a function of uniaxial stain, using density-functional theory. In the presence of an applied strain along 110 or 111, the C interstitial in ferrite is significantly stabilized, while the C vacancy in cementite is moderately destabilized by the corresponding strain states in cementite 100 and (010). The enhanced stabilization of the C interstitial gives rise to an increase in the C concentration within the ferritic layers by up to two orders of magnitude. Our results thus suggest that in addition to the generally assumed non-equilibrium, dislocation-based mechanism, there is also a strain-induced thermodynamic driving force for the experimentally observed accumulation of C in ferrite.
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机译:为了研究实验观察到的严重塑性变形珠光体线铁素体层中C积累的热力学驱动力,利用密度泛函理论研究了铁素体中C间隙和渗碳体中C空位的稳定性作为单轴染色的函数。在沿[110]或[111]施加应变的情况下,铁素体中的C间隙显著稳定,而渗碳体中的C空位则因渗碳体[100]和([010])中的相应应而适度失稳。C 间隙的增强稳定性使铁素体层内的 C 浓度增加了两个数量级。因此,我们的结果表明,除了通常假设的非平衡、基于位错的机制外,实验观察到的铁氧体中 C 的积累还存在应变诱导的热力学驱动力。
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