微合金化元素对Cu-Cr-Nb系合金的相变和高温蠕变行为的影响规律

For the current high strength, high thermal conductivity copper alloys, it is increasingly difficult to meet the requirements of high strength, high thermal conductivity and high creep resistance of thermal sinking materials for rocket engines and nuclear reactors. This proposal intends to take high thermal conductivity, high creep resistance Cu-Cr-Nb copper alloy as the object. This project is proposed to reveal the mechanisms of micro-alloying elements to improve the strength and the creep resistance of Cu-Cr-Nb alloy through the micro-alloying combined with the first principle calculation, ultrastructure characterization at the atomic level, performance testing, and et al. The main research contents include: ① the optimal design of composition and preparation process; ② the influence of micro-alloying elements on the behavior of Cr2Nb precipitation in rapid solidification and the behavior of nanophase precipitation during aging, and ③ the influence mechanisms of Cr2Nb phase and precipitates on high temperature creep behavior of the designed alloys. The project intends to solve two key scientific problems: ① the effects of alloying elements on the Cr2Nb phase solidification behavior and the phase transition behavior during aging; and ② the influence of alloying elements on the size and distribution of Cr2Nb phase formed during solidification, the influence on the heat resistance stability of nanoscale phase precipitated by aging precipitation, and its influence on the high temperature creep behaviors. The completion of this project will lay a theroretical and experimental foundation for developing new high strength, high thermal conductivity, high temperature creep resistant copper alloys.

目前的高强高导铜合金难以满足火箭发动机和核反应堆用热沉材料的高强、高导热和高抗蠕变性能要求。本项目拟以高导热、高抗蠕变Cu-Cr-Nb系合金为研究对象，通过微合金化进一步提升其综合性能，结合第一性原理计算、超微结构表征和性能测试揭示微合金化元素提高强度和抗蠕变性能的机理。主要研究内容包括：①微合金化成分优化设计和喷射沉积制备工艺优化；②揭示微合金化元素对快速凝固Cr2Nb相析出行为和时效纳米相析出行为的影响规律；③阐明微合金化耐热合金快速凝固析出相Cr2Nb和时效析出纳米相对合金高温蠕变行为的影响机理。拟解决两个关键科学问题：①微合金化元素对凝固析出Cr2Nb相和时效析出相变行为的影响规律；②合金化元素对凝固析出Cr2Nb相的尺寸和分布、时效沉淀析出纳米相的耐热稳定性、以及合金高温蠕变行为的影响机理。项目的完成将为新型高强、高导热、高抗蠕变耐热铜合金材料提供理论和实验基础。

项目以Cu-Cr-Nb系耐热铜合金为研究对象，通过计算结合实验验证优化合金化元素的成分与配比，采用粉末冶金法制备坯锭，结合性能测试和超微结构表征优化制备工艺。充分利用微合金化合金的Cr2Nb相以及时效析出纳米相提升材料综合性能。. 项目周期内已经完成项目研究内容、研究目标，解决了关键科学问题，揭示了微合金化元素对合金凝固析出Cr2Nb相和时效析出相变行为的影响规律，探索了合金化元素对凝固析出Cr2Nb相的尺寸和分布、时效沉淀析出纳米相的耐热稳定性。制备出新型高强度、高导热、高抗蠕变耐热铜合金；建立基于第一性原理计算与实验验证相结合的成分设计和组织结构设计原则；阐明了合金化元素交互作用及其影响耐热铜合金快速凝固过程和沉淀析出相变过程的规律；探明凝固析出的Cr2Nb相和沉淀析出纳米相对合金性能的影响机理；获得了高强度、高导热、高抗蠕变耐热铜合金的成分设计、制备工艺、组织结构与性能的关系。. 项目周期内发表SCI论文14篇（均有标注资助），中文论文1篇，申请并获得国家发明专利2项，培养研究生2人。. 项目采用大气熔炼法和粉末冶金法制备了Cu-4.06Cr-1.25Nb (wt.%) 合金，经950 ℃/4 h均匀化+900 ℃热轧80%+940 ℃/4 h固溶处理+冷轧50%+400 ℃时效处理2 h后，大气熔炼法制备的Cu-4.06Cr-1.25Nb合金的电导率为77.8% IACS，在室温、400 ℃、450 ℃、500 ℃下的抗拉强度分别为440 MPa、285 MPa、266 MPa、230 MPa。经950 ℃/4 h均匀化+900 ℃热轧80%+940 ℃/4 h固溶处理+冷轧50%+400 ℃时效处理2 h后，SPS烧结粉末冶金法制备的Cu-4.06Cr-1.25Nb合金的电导率为68.1% IACS，在室温、400 ℃、450 ℃、500 ℃下的抗拉强度分别为496 MPa、256 MPa、212 MPa、165 MPa。. 该项目目前还未体现出直接经济价值和效益，但是为后续的CuCrNb合金的产业化提供了试验和技术基础，有望为我国高端热沉零部件（如火箭发动机燃烧室）提供新的高性能铜合金候选材料。