Zhao Chao, Li Daoxi, Liu Xiaotao, Sun Minghan, Wang Zhi, Luo Zongqiang, Zhang Weiwen
School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China.
Materials (Basel). 2023 Feb 1;16(3):1252. doi: 10.3390/ma16031252.
Grain refinement has been found to be an effective method for simultaneously enhancing strength and toughness. To avoid the sharp coarsening of grains in Cu-Ni-Sn alloys during solution treatment and thereby overcoming the tradeoff between strength and ductility, this work attempted to modify the composition and improve the thermal stability of the fine-grained structure in Cu-Ni-Sn alloys. The grain growth behavior during a solution treatment of the Cu-15Ni-8Sn alloys with/without Si and Ti additions was systematically investigated. The result reveals that compared to the grain size of 146 μm in the based alloy (without trace additions) after solution processing at 1073 K for 2 h, the fine-grained structure with a size below 20 μm is maintained owing to the benefit from Si and Ti addition. It was observed that the addition of Si and Ti offer the inhibition effect on the dissolution of the γ phase and NiSiTi particles after solution treatment. The grain boundary movement is severely hindered by these two aspects: the pinning effect from these particles, and the drag effect induced by additional solute atoms. Based on the analysis of grain growth kinetics, the activation energy of grain growth is increased from 156 kJ/mol to 353 kJ/mol with the addition of Si and Ti.
细化晶粒已被发现是一种同时提高强度和韧性的有效方法。为了避免在固溶处理过程中Cu-Ni-Sn合金中晶粒急剧粗化，从而克服强度和延展性之间的权衡，这项工作试图改变成分并提高Cu-Ni-Sn合金中细晶组织的热稳定性。系统研究了添加和不添加Si和Ti的Cu-15Ni-8Sn合金在固溶处理过程中的晶粒生长行为。结果表明，与在1073 K下固溶处理2 h后的基体合金（无微量添加）中146μm的晶粒尺寸相比，由于添加了Si和Ti，尺寸低于20μm的细晶组织得以保持。观察到，添加Si和Ti对固溶处理后γ相和NiSiTi颗粒的溶解具有抑制作用。晶界移动受到两个方面的严重阻碍：这些颗粒的钉扎效应以及额外溶质原子引起的拖曳效应。基于晶粒生长动力学分析，添加Si和Ti后，晶粒生长的激活能从156 kJ/mol增加到353 kJ/mol。
