晶界/相界界面结构效应多孔钛构建及储氚固氦性能研究

In the application of tritium and helium storage of porous titanium used in nuclear industry, the production and accumulation of helium could led to the decrease of the critical threshold and the degradation of material mechanics performance. The purpose of this research is to achieve long-term stable service. This paper will research on the aspects of pore structure stereoscopic optimization design of porous titanium, fiber/powder synchronous SPS rapid sintering and molding, and the controllable keeping activity of helium. Combined with the synchronization sintering mechanism of new structure， the analysis of mechanical properties and the helium placeholder distribution, this paper will research the porous titanium preparation of grain boundary/phase boundary interface structure effect systematically and improve the comprehensive behavior of the tritium and helium storage critical threshold. This project will explore the microporous design and construction of porous titanium with the character of superfine crystal in nm/nano and super-large specific surface area and will explorer the evolution of sintering neck formed in fiber/powder different forms synchronous sintering and the sintering mechanism, and developing the preparation technology of porous titanium with the character of high-performance tritium and helium storage. In this project, the way of hydrogen/ deuterium ion injection will used in the research of helium storage ability of porous titanium materials to find the placeholder and the distribution of helium in titanium fiber porous materials and the evolution regulation of different stages in long-term storage, and ascertaining the correlation of the porous titanium microstructure materials. Based on this research project, we will achieve the theory of improving the service life of tritium store device and achieve the theory of practice.

针对核用多孔钛在储氚固氦应用中氦产生累积导致临界阈值下降，材料力学性能劣化的应用难题，以实现长期稳定服役的目的。本项目从多孔钛立体结构优化设计，纤维/粉末同步SPS快速烧结成型，氦量保持行为可控，结合新型结构同步烧结机制、力学性能分析及氦的占位分布，系统研究晶界/相界界面结构效应多孔钛制备和提高储氚固氦临界阈值综合行为。探索具有微/纳米超细晶、超大比表面积多孔钛微孔设计和构建、纤维/粉末不同形态同步烧结过程中烧结颈的演化和烧结机制，开发高性能储氚固氦用多孔钛制备技术。采用离子注氢/氘模拟实验研究多孔钛固氦能力，获得氦在多孔材料中占位分布及长期储存中的不同阶段演化规律，探明多孔钛微结构调控与其储氚与固氦行为相关性，获得提高储氚原器件的寿命理论和实践依据。

纯钛是迄今发现的金属材料中吸氢密度最高的材料之一，常用作储存氚的靶材或储氢材料，从多孔钛立体结构优化设计，纤维/粉末、粉末/粉末同步SPS快速烧结成型，探索多孔钛原料性能对孔结构特性的构建原则和制备技术，揭示多孔钛材料中纤维与粉末界面交互作用的烧结微观机制。在材料制备过程中，通过SPS烧结研究根据不同成型压力和不同烧结温度下孔结构的构建及显微组织的变化规律。SPS粉末/纤维复合孔结构多孔钛孔隙率范围为1.10~22.65%，孔径主要分布在20~150μm，样品孔隙率随着烧结温度、烧结压力和纤维含量的增加而呈下降趋势。烧结后样品主要物相结构为密排六方的α-hcp Ti，且烧结温度和压力对物相组成影响不大。在烧结温度为800℃时，显微组织主要由等轴α和针状α组成，并含有少量孪晶，纤维上晶粒相比粉末上更加细小；升温到900℃时，显微组织同样以等轴α为主，但出现少量针状α和片层β组织；1000℃时，显微组织演变为锯齿状α片群和片层β组织。烧结后样品同时具有良好的塑性和较高的强度。综合样品孔结构、显微组织和压缩性能等，研究认为SPS粉末/纤维多孔钛最优烧结工艺为：烧结温度900℃、烧结压力15MPa、纤维含量4%，此时样品孔隙率为5.91%，弹性模量为5.69GPa，屈服强度为272.41MPa，抗压强度为700.75MPa(ε=30%)。采用高温气相充氢模拟钛合金在低氢浓度下长期服役期间的氢累积量，研究氢致钛合金室温组织、室温拉伸性能、高温压缩性能、断裂韧性和疲劳裂纹扩展行为演变及其微观作用机制，分析了高充氢钛合金中氢化物析出类型和相应析出机制，取得了氢或主要合金元素重新再分布的间接证据。通过调控注入He 离子能量和剂量的方式实现涂层预定位置仿真中子辐照损伤效应和氚老化效应，研究多孔钛样品层中注入He 或He 泡的分布及大小不同结果发现微/纳米超细晶、超大比表面积多孔钛晶界界面为捕获吸纳He提供了丰富的位点，不仅显著减少了He在晶粒内部累积损伤，而且还能抑制He元素在阻挡材料内部扩散迁移。