多元掺杂钨合金中复杂氧化物的析出调控及强韧化机理研究

W has been considered as important candidate material for plasma facing materials in fusion system. The limited operational temperature range of W due to the high ductile-to-brittle transition temperature and recrystallization induced brittleness can be extended by dispersion strengthening. However, particles with relatively large size tend to locate along grain boundaries (GBs), which contribute little to improve the high temperature strength and the brittleness resulted from the impurities concentrated on GBs. In order to solve this performance limiting issue, this project aims to investigate the precipitation control of complex oxide particles and the related strengthening-toughening mechanism in multi-doped W alloy. The research contents are as following: (1) investigation of the solution behavior of multi-doped constituents in W matrix during high energy ball milling to achieve fully mechanical alloying, (2) investigation of the relationship between heat treatments and precipitation behavior of complex oxide particles to tailor their size and distribution, and (3) characterization of microstructure and analysis of mechanical properties to understand the related strengthening-toughening mechanism. Based on the above study, a novel method and technique of obtaining W alloy with uniformly dispersed nanoscaled complex oxide particles will be developed. This project will provide scientific basis on how to develop high-performance W alloy for plasma facing materials in fusion system.

钨是聚变堆面向等离子体材料的重要候选材料。弥散强化有望扩宽钨由于低温及再结晶脆性造成的狭窄服役温度窗口。但是，制备过程中弥散相易在晶界处形成大尺寸颗粒，导致强化效果差且无法有效改善晶界杂质造成的脆性，严重限制了其工程实际应用。针对上述问题，本项目拟开展多元掺杂钨合金中复杂氧化物的析出调控及强韧化机理研究，主要包括（1）探究高能球磨过程中多元组分在钨基体中的固溶行为，制备多元掺杂机械合金化钨粉；（2）系统研究热处理工艺参数对复杂氧化物析出行为的影响规律，建立钨合金中复杂氧化物形成与演化行为的调控机理；（3）结合微结构和力学性能测试结果，阐明复杂氧化物对钨合金强韧化的作用机理。在此基础上，形成多元掺杂钨合金中纳米复杂氧化物的析出及其可控分布的新方法/新技术，为研发高强韧钨合金并最终应用于聚变堆面向等离子材料提供科学依据。

针对氧化物弥散强化钨合金中弥散颗粒易在晶界处形成大尺寸颗粒，导致强化效果差且无法有效改善晶界杂质造成的脆性问题，本项目围绕多元掺杂钨合金中复杂氧化物的析出调控及强韧化机理开展了研究，取得的主要研究成果如下：（1）与简单掺杂方式相比，多元掺杂机械合金化粉末颗粒更细且具有更多的晶体缺陷，有助于提高稀土氧化物组分在钨基体中的固溶度；（2）多元掺杂W-YT合金中弥散相为纳米级复杂Y2Ti2O7，晶内弥散相占比有所提高且与钨基体呈共格关系；（3）通过调控烧结制度即在1000℃保温5min保证纳米的γ-Al2O3形成，实现了含Al多元掺杂钨合金中弥散相的细化及强韧性的改善。（4）多元掺杂钨合金强韧性的改善得益于复杂氧化物弥散相吸收了多余的氧杂质及其晶粒细化作用。基于此，提出了可形成复杂氧化物弥散相的多元掺杂钨合金成分设计原则。本项目的研究成果为制备高强韧钨合金提供了新的途径和技术支撑，为其在聚变堆等极端环境中的工程应用奠定了一定的基础。