Precipitation evolution and properties of Cu-15Ni-8Sn alloys via Al microalloying during ageing  

作　　者：Wei Luo Li-Jun Peng Xu-Jun Mi Hao-Feng Xie Yi-Cheng Cao Shu-Hui Huang 

机构地区：[1]State Key Laboratory of Nonferrous Metals and Processes,GRINM Group Co.,Ltd.,Beijing 100088,China [2]GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China [3]General Research Institute for Nonferrous Metals,Beijing 100088,China [4]School of Materials Science and Engineering,South China University of Technology,Guangzhou 510640,China

出　　处：《Rare Metals》2024年第10期5216-5228,共13页稀有金属（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(No.52271038);the Technological Innovation 2025&Major Special Project of Ningbo(No.2021Z084)。

摘　　要：Studies have shown that microalloying Cu-Ni-Sn alloys using Al inhibits discontinuous precipitation reactions;however,the mechanism has not been investigated yet.Thus,this study explored the properties and precipitation evolution of Cu-15Ni-8Sn alloys without and with 1 wt%Al(Cu-15Ni-8Sn-1Al)during ageing at 500℃ through X-ray diffraction(XRD),scanning electron microscopy and high-angle annular dark-field scanning transmission electron microscopy.The results revealed that in Cu-15Ni-8Sn alloy,DO_(22)ordering first occurred after spinodal decomposition,subsequently transitioning to an L1_(2)ordering phase,during which the discontinuous precipitates gradually nucleated at the grain boundaries and formed ingrains.The alloy hardness increased sharply with ordering and then decreased rapidly after reaching its peak value,due to the dominance of the discontinuous precipitation reaction.However,the DO_(22)ordered phase did not appear during the ageing of Cu-15Ni-8Sn-1Al alloy,and a Ni_(3)(Al_(x),Sn_(1-x))intermetallic compound with L1_(2)structure was formed,consuming Ni and Sn atoms,thereby significantly suppressing the discontinuous precipitation reaction and improving the stability during prolonged ageing.The tensile strength(yield strength)of Cu-15Ni-8Sn and Cu-15Ni-8Sn-1Al alloys at peak hardness were 855(755)and 936 MPa(892 MPa),respectively,and their main strengthening mechanisms were solid solution strengthening and precipitation strengthening.The addition of 1 wt%Al effectively improved the precipitation strengthening effect of Cu-Ni-Sn alloys but severely decreased the ductility.

关 键 词：CU-15NI-8SN Al addition Precipitation sequence Strengthening mechanism 

分 类 号：TG166.2[金属学及工艺—热处理]