基于纳米碳化物弥散和晶界净化制备高强韧钨基材料及其性能优化机理研究

Tungsten materials are promising candidates for plasma-facing materials in fusion reactors. However, current tungsten materials could not satisfy the requirement for practical application, and tungsten materials with excellent mechanical properties, high-temperature stability as well as thermal-shock resistance are highly needed. The present proposal plans to enhance the strength and toughness of tungsten materials by nanosize carbide dispersion and grain boundary purification. Trace Zr, C or ZrC would be employed to diminish the detrimental effect of impurity elements, such as O, N, and hence purify/strengthen grain boundary and improve the low-temperature ductility. At the same time, very small (<10 nm) second-phase (ZrC) particles introduced in tungsten by solution-precipitation method could elevate the strength, toughness and high-temperature properties. Additionally a large amount of particle-matrix phase interfaces would be promising for enhancing the thermal-shock resistance and irradiation resistance. Therefore, nanostructured W-Zr-C alloys with excellent comprehensive properties can be expected. Basing on the W-Zr-C alloys, multi-component W-Zr-Ta-C alloys would be developed, due to their potential in reducing deuterium/tritium retention and inhibiting hydrogen bubble formation. The preparation technology and mechanism of carbide particle refinement, as well as the synergistic effect of nanosize carbide dispersion and grain boundary purification on the comprehensive properties of tungsten materials would be systematically investigated. The project will provide theoretical and experimental foundation for the development of high-performance tungsten materials required for fusion reactors and other extreme applications.

钨基材料是核聚变堆面向等离子体材料的主要候选者，但目前的钨基材料在力学性能、高温稳定性和抗热冲击性能等方面不能满足实际应用的要求。对此，本项目拟通过纳米碳化物弥散和晶界净化协同提升钨基材料的强韧性：通过微量Zr、C或ZrC调控杂质O、N而净化/强化钨晶界和提高材料的低温韧性，同时利用固溶-析出机制使第二相颗粒（ZrC）控制在10nm以下且均匀分布在细小钨晶粒中，从而大幅提高材料的强度、韧性和高温性能，并利用ZrC与钨基体之间形成的大量相界面提高抗热冲击性能和抗辐照性能，最终研制出综合性能优异的钨基合金(W-Zr-C体系)。在此基础上发展多元W-Zr-Ta-C合金，使合金具有更优的氘氚滞留特性和抗氢泡形成能力。本项目将系统地研究钨中碳化物颗粒细化的工艺和机理，阐明纳米碳化物弥散和晶界净化协同提升钨基材料综合性能的微观机理，为聚变堆及其它极端条件下使用的高性能钨基合金的研发提供理论和实验基础。

钨被认为是最有前景的聚变堆面向等离子体材料，但钨存在室温脆性、再结晶脆性、辐照脆化等不足。针对钨基材料面临的主要问题，我们基于纳米碳化物弥散和晶界净化开展高性能钨合金材料的制备及性能优化机理研究，制备了W-ZrC、W-Zr/Ta-C等纳米碳化物弥散增强的钨合金材料，考察了纳米碳化物尺寸、含量及制备工艺对钨合金力学性能、高温稳定性、热负荷性能及抗辐照性能的影响规律，研制了若干体系高性能的钨合金材料。通过固溶-析出、激光粉碎等方法，使W-ZrC合金中ZrC颗粒尺寸细化至10nm以下；在纳米碳化物弥散钨合金基础上，发展了钨合金的复合强韧化方法，探索制备了高温高强韧的W-ZrC-K、W-ZrC-Re合金等材料。研制的纳米结构W-ZrC合金板材具有优异的力学性能、高温稳定性、抗热负荷冲击、抗等离子体刻蚀和抗中子辐照性能，综合性能指标处于国际先进水平，被国家重点研发计划《CFETR国产先进材料小样品高剂量中子辐照及结构性能测评》项目组选为入堆辐照的两种国产先进钨基材料之一。相关研究为我国未来聚变堆用高性能钨基材料的研发提供了科学基础。