Fe50Rh50体系中的预马氏体与马氏体

铁基合金FCC-BCC相变马氏体生长的波动模型

The wave model of martensite growth for the FCC-BCC transformation of iron-based alloys

这本书是科学文献中的第一本专著，致力于铁基合金中的FCC-BCC转变，其中动力学方法用于解释马氏体生长阶段。冷却马氏体晶体的快速生长被认为是一个由准纵向晶格位移波（DW）控制的自组织过程。DW初始激励的状态是刚性的。DW具有来自超声波带的频率~ $10^{10} sec^{-1}$和提供变形水平~ $10^{-3}$的振幅。分析了非平衡d电子产生DW的必要条件。广泛的问题（从电子光谱的特性宏观形态指标），与铁基合金的FCC-BCC马氏体相变的物理解释，进行了讨论。在专着的结论中给出了对建立描述马氏体形核过程的物理模型具有根本意义的结果的简短回顾。结果表明，非均匀形核和波动长大过程与FCC-BCC马氏体相变有着遗传联系。最后一位作者的结果揭示了FCC-BCC马氏体相变的所有替代品的马氏体晶体形成的物理机制控制过程的特点的简短回顾给出了专着的结语。

FeC和FeN马氏体的弹性性能

Elastic Properties of FeC and FeN Martensites

用基于密度泛函理论的从头计算方法计算了体心立方铁和体心立方FeC、FeN合金的单晶弹性常数。应变晶体的能量已被计算在几个值的应变强度使用超胞方法，和刚度系数已被确定从能量与应变关系的平方的斜率。一些三阶弹性常数也进行了评估。体心立方铁的计算值的绝对值是在公平的协议与实验，包括三阶常数，虽然计算的弹性各向异性是比测量弱得多。四边形扭曲的稀释FeC和FeN合金表现出较低的刚度比体心立方铁，特别是在张量分量C33，而弹性各向异性几乎是相同的。还计算了多晶团聚体的弹性模量的平均值。杨氏模量和刚性模量，以及体积模量，减少了约10%，通过添加C或N到3.7原子百分比，这与FeC马氏体的实验数据相一致。

铁基合金fcc-bcc马氏体相变的物理本质

Physical nature of fcc-bcc martensitic transformation in iron based alloys

总结了作者提出的揭示马氏体晶体形成物理机制特征的模型。冷却马氏体晶体的快速生长被认为是一个由准纵向晶格位移波（DW）控制的自组织过程。结果表明，在自发的fcc-bcc马氏体相变中，非均匀形核和波动生长过程具有遗传联系。应变马氏体形成的博览会被认为是在一个晶体模型的背景下。

An atomistic perspective of martensite twinning in Iron

The martensitic transformation is one of the most important phenomena in metals science due to its essential contribution to the strength of steels and most engineering alloys. Yet the basic, atomistic mechanisms leading to martensite nucleation and twin morphology are not yet known. A detailed picture in this regard is required if the strengthening effects of martensite are to be properly understood. This work presents molecular dynamics (MD) simulations of the martensitic transformation using a model fcc/bcc semi-coherent interface with Nishiyama-Wasserman orientation relationship. Significa…

fcc-bcc马氏体相变的一步理论

One-step theory of fcc-bcc martensitic transformation

钢中的马氏体相变是它们非常高的强度的原因，因此自Martens的第一部作品以来，已经研究了一个多世纪。然而，还没有简单的物理理论。一个严格的分类的晶体subgroupoid（包）的KS变种和KS，NW和Pitsch变种之间的连续性被引入到代表与马氏体相变的晶体错综复杂。从这个分析，提出了一个新的简单的理论的基础上Pitsch失真。扭曲尊重铁原子的硬球包装，并意味着存在一个中性线沿紧密包装的方向。其主应变为0、-5.8和+15.5%，远低于贝恩畸变的+12、+12和-20%值。马氏体变体通过相变连续变形的奥氏体基体中的Pitsch畸变形核。马氏体变体通过相同的Pitsch畸变生长;它们局部处于Pitsch取向，因此在奥氏体的变形场内逐渐取向，导致包括KS和NW的连续取向。现在可以重新解释文献中报道的许多观察结果。

Extensive anisotropic lath martensite plasticity in dual-phase steels: A numerical-experimental investigation

This work presents a detailed experimental-numerical analysis of a low-carbon dual-phase steel microstructure, revealing evidence of significant anisotropic plastic deformation in lath martensite. A careful determination of the habit plane orientations in the present martensitic variants demonstrates that the observed traces of plastic slip coincide with the directions of the corresponding habit planes. To study the local lath martensite plastic activity, a dedicated substructure-enriched crystal plasticity based model is exploited. Compared with conventional bcc crystal plasticity, the model …

钢中核壳Cu析出的原子尺度研究：原子探针断层扫描与第一性原理计算

Atomic-scale study on core-shell Cu precipitation in steels: atom probe tomography and ab initio calculations

本研究结合APT、DFT和MD模拟，揭示了中锰钢中纳米级核壳Cu析出物的形成机制，发现Ni和Al在析出物外壳形成稳定共偏析以抑制Cu析出物生长，为开发Cu污染循环钢提供了理论方法。

Design of a V-Ti-Ni alloy with superelastic nano-precipitates

Stress-induced martensitic transformations enable metastable alloys to exhibit enhanced strain hardening capacity, leading to improved formability and toughness. As is well-known from transformation-induced plasticity (TRIP) steels, however, the resulting martensite can limit ductility and fatigue life due to its intrinsic brittleness. In this work, we explore an alloy design strategy that utilizes stress-induced martensitic transformations but does not retain the martensite phase. This strategy is based on the introduction of superelastic nano-precipitates, which exhibit reverse transformatio…

Grain boundary-induced martensitic transformations: A phase-field study of nucleation, size-effect, triple junction-effect, microstructures, and compatibility at the nanoscale

An original thermodynamically consistent large strains-based multiphase phase-field (PF) approach of Ginzburg-Landau type is developed for studying the grain boundary (GB)-induced martensitic transformations (MTs) in polycrystalline materials at the nanoscale considering the structural stresses within the interfaces. In this general PF approach, N independent order parameters are used for describing the austenite (A)<->martensite (M) transformations and N(>1) martensitic variants, and another M independent order parameters are considered for describing M(>1) grains in the polycrystalline sampl…

Minimization of atomic displacements as a guiding principle of the martensitic phase transformation

We present a unifying description for the martensitic transformation of steel that accounts for important experimentally observable features of the transformation namely, the Neumann bands, the interfacial (habit) plane between the transformed and untransformed phases and their orientation relationship (OR). It is obtained through a simple geometric minimization of the total distance traveled by all the atoms from the austenite (FCC or $γ$) phase to the martensite (BCC or $α$) phase, without the need for any explicit energy minimization. Our description unites previously proposed mechanisms bu…

Towards the ab initio based theory of the phase transformations in iron and steel

Despite of the appearance of numerous new materials, the iron based alloys and steels continue to play an essential role in modern technology. The properties of a steel are determined by its structural state (ferrite, cementite, pearlite, bainite, martensite, and their combination) that is formed under thermal treatment as a result of the shear lattice reconstruction "gamma" (fcc) -> "alpha" (bcc) and carbon diffusion redistribution. We present a review on a recent progress in the development of a quantitative theory of the phase transformations and microstructure formation in steel that is ba…

通过固态轻推弹性带方法的磁结构变换：在压力下铁的应用

Magneto-structural transformations via a solid-state nudged elastic band method: Application to iron under pressure

我们扩展了固态轻推弹性带方法来处理一个非保守的序参量-特别是磁化，耦合到体积，并导致许多观察到的磁系统中的效果。我们将这种形式主义的压力诱导铁的转变过程中，从铁磁体心立方（BCC）奥氏体六方密排（HCP）马氏体的研究磁体积崩溃。我们发现bcc-hcp平衡共存压力为8.4 GPa，在此压力下的过渡态焓为156 meV/Fe。磁化强度和相干应力的不连续性发生在过渡态，它具有一个尖点的形式上的势能面（但所有的原子和细胞的自由度是连续的）;计算的压力跃变25 GPa是与所观察到的25 GPa的扩展测量共存压力所产生的样品中的马氏体和相干应力。我们的结果与实验一致，但必然不同于那些所产生的阻力和限制参数化方法有不适当的约束或不受控制的自由度。