聚变堆用V-4Cr-4Ti合金的机械合金化过程与性能研究

V-4Cr-4Ti alloy is assigned as the first candidate structural material for liquid Li blanket of fusion reactors in the future. Nowadays, the high-temperature strength of this alloy still needs to be enhanced further. This work considers to use mechanical alloying (MA) for strengthening the V-4Cr-4Ti alloy, and improve its creep resistance at high temperatures. The main studies of this work include: (1) to study the dissolution behaviours of alloying elements during the mechanical alloying process; (2) to study the effects of nano-particle size, density and grain size on the high-temperature deformation of the mechanical alloyed V-4Cr-4Ti material; (3) to study the effects of thermal stability and coherency conditions of nano-particles on the strengthening for mechanical alloyed V-4Cr-4Ti material. Mechanical properties of these alloys are to be tested at room temperature and high temperatures which meet the operation requests of a fusion reactor. Microstructures are observed to investigate the strengthening mechanisms. A large scale dispersion strengthened V-4Cr-4Ti alloy of 2 kg and with high performance is to be fabricated for further studies in the future. This work is expected to benefit the strengthening of fusion structural materials, enhancing the safety and saving of the blanket components. The achievements of MA process study and strengthening mechanisms are expected to provide the optimization of MA fabrication for other metals with scientific principles.

V-4Cr-4Ti合金是未来核聚变堆中液态自冷包层的首选结构材料。针对该合金的高温力学性能还有待进一步增强的现状，本课题拟采用机械合金化的方法来强化该合金，使其抗高温蠕变性能大幅提升。项目将分析（1）高能球磨条件下，各主要合金元素在基体中的合金化过程；（2）弥散粒子尺寸、密度和晶粒大小对V-4Cr-4Ti合金高温变形行为的影响；（3）不同热稳定性和共格特性的弥散粒子对V-4Cr-4Ti合金的强化效果等要点。实验将参考聚变堆部件的工况条件，通过室温、高温力学性能测试和显微结构分析，研究该合金的强化效果和内在机理；并利用优化的工艺，指导生产出2公斤的高性能弥散强化V-4Cr-4Ti合金，为今后的其它研究作基础。本项目的实施，对聚变堆结构材料的强化有重要现实意义，可以提升包层部件的工程安全性和经济价值；所研究出的合金化过程和强化规律可以为其它金属材料的机械合金化工艺优化提供科学依据。

V-4Cr-4Ti 合金是未来聚变堆中液态锂包层的首选结构材料，它的高温强度和抗中子辐照抗力这两项关键性能都可以通过机械合金化来获得提升。机械合金化的钒合金中，多种沉淀相可以起到一个叠加的弥散强化效果。这些弥散颗粒的各种属性，尤其是热稳定性会对高温强化起到一个非常重要的影响。为了优化高温应用下钒合金的弥散强化颗粒选择，本课题主要研究了钒合金在添加钇和碳化物等物质后的强化。为了更好地认识不同纳米颗粒的强化效果，本研究进行了合金化程度、晶粒度、致密度、杂质含量等多方面影响因素的对比。虽然碳化物的溶解可能非常微弱，但依然发现了Ti3SiC2 的添加对钒合金起到了非常显著的强化作用，并且经过1450oC退火后依然最稳定。