CuNiMnFe合金中溶质原子迁移过程的调控及强韧化机理研究

CuNiMnFe alloy has poor plasticity and toughness due to coarse dendrite structure, large segregation of primary precipitation phase in the interdendritic and at the grain boundary, and the vacancy effect formed by the Cu matrix lattice vacancy caused by a large number of solute atom precipitation after the secondary phase generated. In order to improve its plasticity and toughness, the project study the microstructure evolution of as-cast CuNiMnFe alloy under different load condition, and the effect of deformation treatment, applying positive and negative load, and the ageing treatment on precipitation behavior of CuNiMnFe alloy. From above investigations, the factors which affect the plasticity are disclosed, and the methods are proposed to refine the microstructure, inhibit the composition segregation and control the primary phase of as-cast CuNiMnFe alloy, along with the regulation measures of size, amount and distribution for ageing precipitates. The investigation can provide new ideas for the improvement on the plasticity for the multiple copper alloys with high solute content, and acquire new knowledge of grain refinement by controlling melt structure and precipitation strengthening phase regulation under the action of mechanical load for multiple CuNiMnFe alloy. Subsequently, it can lay the foundation of the preparation of the high-strength and high-ductility copper alloys with high solute content as well.

针对高溶质含量的CuNiMnFe合金因树枝晶粗大、溶质偏析、初生相偏聚及次生相析出不均匀等原因导致其塑性和韧性较低的问题，本项目拟通过在凝固过程中对熔体、半固态和高温固态合金施加压应力，在时效处理时，施加预制应力与在线轴向压（拉）应力，分别用于调控CuNiMnFe熔体凝固时溶质原子的迁移和时效时溶质原子脱溶过程，期望改善合金的组织缺陷。研究重点在于：阐明压应力作用下高溶质铜合金熔体中溶质元素分布及晶体生长中原子堆垛方式与铸态组织细化的内在关系，揭示不同加载方式对高溶质铜合金中次生相析出行为的影响规律。在此基础上，对合金的凝固和时效过程进行调控，实现高溶质含量的CuNiMnFe合金强度提高的同时保持良好的塑性和韧性。研究结果可提供一种改善高溶质的多元铜合金强度和韧性的新方法；获得预制应力与在线应力作用下调控次生相析出方式的新知识，为制备高强高韧性高溶质铜合金奠定基础。

本项目针对高溶质含量的CuNiMnFe合金凝固组织中树枝晶粗大、成份偏析和初生相偏聚，以及时效处理过程中次生相析出不均匀等原因导致其塑性和韧性较低的问题深入研究。通过在凝固过程中对熔体、半固态和高温固态CuNiMnFe合金施加压应力，并在后期时效处理时对合金施加预制应力与在线轴向压（拉）应力，分别用于调控CuNiMnFe熔体凝固时溶质原子的迁移和时效时溶质原子脱溶过程。研究结果得到了一种压力凝固制备细晶粒CuNiMnFe合金的方法，提供了一种改善高溶质含量CuNiMnFe合金强度和韧性的新方法。阐明压应力载荷作用下，CuNiMnFe合金晶粒细化过程、晶体生长行为及次生相析出方式；揭示高溶质铜合金凝固过程中，应力载荷调节溶质原子迁移和堆垛方式，以及预制应力与在线应力下次生相析出动力学规律；建立应力载荷调控高溶质铜合金溶质元素的有效分布，提高塑性和韧性的新知识，为制备高强高韧性高溶质铜合金奠定基础。