Wang Mingfei, Chen Shuaifeng, Wang Songwei, Zhang Mengxiao, Song Hongwu, Zhang Shihong
School of Rare Earths, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026, China.
Ganjiang Innovation Academy, Chinese Academy of Sciences, 1 Science Academy Road, Ganzhou 341119, China.
Materials (Basel). 2023 May 31;16(11):4105. doi: 10.3390/ma16114105.
A Cu-2.35Ni-0.69Si alloy with low La content was designed in order to study the role of La addition on microstructure evolution and comprehensive properties. The results indicate that the La element demonstrates a superior ability to combine with Ni and Si elements, via the formation of La-rich primary phases. Owing to existing La-rich primary phases, restricted grain growth was observed, due to the pinning effect during solid solution treatment. It was found that the activation energy of the NiSi phase precipitation decreased with the addition of La. Interestingly, the aggregation and distribution of the NiSi phase, around the La-rich phase, was observed during the aging process, owing to the attraction of Ni and Si atoms by the La-rich phase during the solid solution. Moreover, the mechanical and conductivity properties of aged alloy sheets suggest that the addition of the La element showed a slight reducing effect on the hardness and electrical conductivity. The decrease in hardness was due to the weakened dispersion and strengthening effect of the NiSi phase, while the decrease in electrical conductivity was due to the enhanced scattering of electrons by grain boundaries, caused by grain refinement. More notably, excellent thermal stabilities, including better softening resistance ability and microstructural stability, were detected for the low-La-alloyed Cu-Ni-Si sheet, owing to the delayed recrystallization and restricted grain growth caused by the La-rich phases.
为了研究添加La对微观结构演变和综合性能的作用，设计了一种低La含量的Cu-2.35Ni-0.69Si合金。结果表明，La元素通过形成富La初生相，表现出与Ni和Si元素结合的卓越能力。由于存在富La初生相，在固溶处理过程中，由于钉扎效应，观察到晶粒生长受到限制。研究发现，随着La的添加，NiSi相析出的激活能降低。有趣的是，在时效过程中，由于固溶过程中富La相对Ni和Si原子的吸引，观察到NiSi相在富La相周围的聚集和分布。此外，时效合金板材的力学性能和导电性能表明，添加La元素对硬度和电导率有轻微的降低作用。硬度降低是由于NiSi相的弥散强化作用减弱，而电导率降低是由于晶粒细化导致晶界对电子的散射增强。更值得注意的是，对于低La合金化的Cu-Ni-Si板材，由于富La相导致的再结晶延迟和晶粒生长受限，检测到了优异的热稳定性，包括更好的抗软化能力和微观结构稳定性。
