Fe-Cr-B-C抗磨合金的组相设计和强韧化机理研究

In order to improve the microstructure and properties of Fe-Cr-B-C wear-resistant alloy and promote the process of industrial application, the multiscale computation is used to analyze quantitatively the influence of different alloying elements on the structure and performance of the phases combining with the advanced micro-nano-scale characterization techniques in project. Firstly, the first-principles calculations and molecular dynamics are used to quantitatively study the solid solubility, distribution, migration and migration of alloying elements in the phases. Secondly, the effect of alloying elements on strengthening-toughening, thermodynamic properties and interface are also investigated to quantitative describe the performance matching of different phases. The theoretical results are verified by means of high resolution transmission electron microscopy, electron probe microanalysis and nanoindentation to select the alloy element type and determine the optimum composition range. Finally, the multiphase thermodynamic model is used to predict the equilibrium phase composition and macroscopic mechanical properties to achieve the goal of quantitatively regulating the optimal phases. This project builds the links between the atomic electron behaviors at the nanoscale and the strengthening-toughening and collaboration of the micro-phases and the macroscopic toughness of the anti-wear resistant alloy. New methods are developed to design and optimize the alloys from the source of atoms, which has important theoretical significance and engineering application values.

Fe-Cr-B-C合金作为年消耗量百万吨以上的抗磨合金，提高其使用性能在节约资源领域具有重要意义。为改善其组织和性能，本项目采用多尺度理论计算结合先进的微纳尺度结构和性能表征技术，定量分析不同合金元素对组相结构和性能演变的影响规律。首先，采用第一原理结合分子动力学，从原子-电子层次定量研究合金元素在不同组相中的固溶度、分配、迁移和扩散，对结构演变的影响；其次，探究合金元素对组相强韧性、热力学性质和界面结合的影响规律，定量描述组相间的性能匹配，结合高分辨透射电镜、电子探针微区分析和纳米压痕验证理论结果，快速筛选合金种类、确定最佳成分范围；最后，通过多相热力学模型预测平衡相组成与宏观力学性能，实现定量调控最优组相的目标。通过将纳米尺度的原子电子行为、微观组相的强韧性、组相间协同性与合金宏观强韧性与抗磨性建立关联，发展从源头快速设计和优化抗磨合金的新方法，具有重要的理论意义和工程应用价值。

为提高Fe-Cr-B-C多组元抗磨合金中各组元间强韧性与性能协同性，本项目整合第一性原理计算、多相热力学模型和先进的微结构和性能表征技术，快速全面的进行合金元素种类的优化选取以及含量确定，探究合金元素的微观行为对组相结构和性能演变的影响规律。通过理论与实验得到的定量结果，建立微观组相的强韧性、组相间性质和界面的协同性与合金宏观强韧性与抗磨性的关联，完成 Fe-Cr-B-C 合金的成分优化与设计，获得最佳组成。结果表明，Cr、Mn、Co和Mo等元素是硬质相合金化的主要候选元素，根据相图计算的结果确定(Fe, M)2(B, C)是Fe-Cr-B-C抗磨合金中最主要的硬质相。通过理论计算结合关键实验确定Cr元素可以同时改善(Fe, M)2B硬度和韧性。对于(Fe, M)7(C,B)3型硬质相，固溶W+B和W+Mo情况下可以改善其韧性但不明显降低其硬度和模量。通过界面性质计算证明了合金元素Cr，Mn，Ni，Nb，Mo，Ta和W均可增加基体相和硬质相界面的稳定性，同时确定Cr，Mn，Ni可以提高基体相与硬质相界面的塑性和强度，即Cr，Mn，Ni作为提高硼铁基合金强韧性的合金元素。最后通过实验获得抗磨合金的强度、耐磨性的宏观力学性能，本项目全面研究了合金元素对Fe-Cr-B-C多组元抗磨合金微观结构、相组成、力学性质，为Fe-Cr-B-C多组元抗磨合金的成分设计提供理论基础与支撑，具有重要的理论意义和工程应用价值。