纳米晶Cu金属材料的协同强化及Hall-Petch效应

This research proposal will select a series of nanocrystalline Cu metallic materials, such as Cu, Cu-Zr、Cu-ZrB2 and Cu-Zr-ZrB2, as the model materials to investigate the influence of ZrB2 nanoparticles and Zr atoms segregated at grain boundaries on Hall-Petch coefficient, k, of nanocrystalline pure Cu. With a detailed and comprehensive microstructural characterization, mechanical measurement and data analysis, the intrinsic dependence of the Hall-Petch coefficient (k) of nanocrystalline Cu on the ZrB2 nanoparticles and grain boundary-segregated Zr atoms will be elucidated and revealed. Based on such findings, we will attempt to construct and validate a modified Hall-Petch relation. After construction, the modified Hall-Petch relation is able to predict the strength of nanocrystalline metallic materials with both dispersed second phase nanoparticles and solute atoms segregated at grain boundaries. The findings from this research proposal are expected to advance the development of the field of nanocrystalline metallic materials.

本项目以系列纳米晶Cu基材料（Cu、Cu-Zr、Cu-ZrB2及Cu-Zr-ZrB2）为研究模型材料，通过材料的显微组织表征、力学性能测试以及数据分析，研究纳米ZrB2颗粒和晶界偏聚Zr原子对纳米晶Cu的Hall-Petch系数k的影响，进而阐明和揭示纳米ZrB2颗粒及晶界偏聚Zr原子与Hall-Petch系数k之间的内在联系。以此为基础，构建和验证修正的Hall-Petch关系式，并把修正后的Hall-Petch关系式用于更准确地预测含有第二相纳米颗粒和晶界偏聚溶质原子的纳米晶金属材料的强度。本项目的研究结果将会对推动纳米晶金属材料领域的发展作出一定贡献。

溶质原子、弥散第二相颗粒及晶界析出相/晶界化学成分深刻地影响着纳米晶/超细晶金属合金的强度、热稳定性及其霍尔佩奇系数。本课题分别研究了纳米尺度富Zr晶界润湿相及富Zr纳米弥散颗粒对合金的加工硬化率及纳米晶粒热稳定性的影响、超细晶Al-Mg合金的霍尔佩奇系数对溶质Mg浓度的依赖和微合金化Ti元素细化和稳定第二相氧化物及铜晶粒的微观机理。主要研究发现有：1）纳米尺度富Zr晶界润湿相的形成提升了合金的加工硬化率；2) 原位生成的富Zr纳米颗粒可稳定纳米铜晶粒至铜的熔点附近；3）超细晶Al-Mg合金的霍尔佩奇系数随Mg浓度的增加而增大；4）微量元素Ti偏聚到氧化物/铜界面处以稳定氧化物颗粒粗化和铜晶粒长大。这些研究结果不仅能为相关合金的设计与开发提供科学参考依据，同时也为后续更深层次的科学研究活动储备了重要的原始数据。