多尺度界面结构协同提升W基第一壁材料服役性能及机理研究

The tungsten based materials are promising candidate of plasma facing materials (PFMs), but the performance of the developed W alloy is far away from satisfying the draconian servicing environment. This project will focus on the issues of low thermal load resistance, insufficient strength/ductility, low irradiation resistance/obvious sputtering corrosion and high hydrogen retention of the current W based candidate PFMs, designing and fabricating the bulk W alloys with coexistence of multi-scaled interface structure: micrometer scaled （～10-15μm）similar columnar grain boundary interface, sub-micrometer (～500-700nm）ultrafine equiaxial sub-grain boundary interface and ultrafine nanoscaled phase boundary interface between refined dispersed strengthening nano particles and W matrix. The purpose is to synergistically improve the mechanical properties, high thermal load resistance, irradiation resistance/plasma sputtering corrosion resistance and decrease the hydrogen retention of W alloy, at the same time to reveal the effects of fabrication and treatment technology parameters on the formation of interface structure in W based materials by analyzing the microstructure; to illustrate the mechanism of synergistic improvement of service performance by the multi-scaled interface structure on the basis of characterization the mechanical properties, high thermal load resistance, irradiation resistance and hydrogen retention as well as simulation; to provide the scientific basis for researching & developing W based PFMs with high performance and engineering application in future fusion reactor.

W基材料是最有前途的聚变堆面向等离子体第一壁材料，但目前发展的W合金综合性能还远不能满足苛刻服役环境需求。本项目针对当前W基材料的低热负荷容限、强韧不足、抗辐照性能不足/等离子刻蚀显著及氢滞留高等问题，设计制备具有集微米级（～10-15μm）类柱状母晶晶界界面、亚微米（～500-1000nm）超细等轴亚晶晶界界面及细小纳米弥散强化颗粒（～20-40nm）相界界面等多尺度界面结构于一体的块体W合金，通过多尺度界面协同作用实现材料的力学性能、抗热负荷性能及抗辐照/抗等离子体刻蚀、氢滞留性能协同提升。分析材料的微结构，揭示制备、处理工艺参数对W基材料界面结构影响规律；表征材料的力学性能、抗高热负荷、抗辐照及氢同位素滞留性能，结合计算模拟，阐明多尺度界面结构共同作用对W基材料服役性能协同提升的机理，为研发高性能第一壁W基材料及其在未来聚变堆的工程应用提供科学依据。

W基材料是最有前途的聚变堆面向等离子体第一壁材料，但目前发展的W合金综合性能还远不能满足苛刻服役环境需求，本项目基于多尺度界面结构协同提升钨基材料综合服役性能的思想，利用粉末冶金方法，通过机械合金化、加压辅助低温致密化烧结或无压高温烧结以及随后的热轧和退火处理，控制形变参数和热梳理工艺参数，制备出系列具有类柱状母晶、具有细小纳米颗粒均匀分散 (ZrC, TaC、 HfC、Y2O3)的超细亚晶于一体的多尺度界面结构W-Y2O3（TaC，ZrC、HfC）块体钨合金。系统地分析了材料的微结构包括类柱状母晶、等轴亚晶及碳/氧化物颗粒的尺寸和分布随初始钨粉体晶粒、制备工艺参数演化规律，揭示钨合金中多尺度界面结构的形成机理；系统地表征了材料的力学性能（包括抗拉/抗弯强度、DBTT和硬度）、抗高热负荷性能和抗中子辐照及氢同位素滞留性能，发现更加细小的第二项纳米颗粒有效抑制钨基体晶粒生长，提升了材料强度和热稳定性，从而进一步提升其抗热负荷性能；高密度的晶界/相界界面有效提升了钨合金抗辐照性能，低剂量中子辐照结果表明，相比纯W及其他钨合金，具有多尺度界面结构的W-ZrC合金的抗辐照性能最优。本项目研究结果，为今后研发高性能抗第一壁材料及其他材料提供了科学依据，同时为面向等离子体钨基材料工程应用提供材料和数据基础。