摘要
用团簇加连接原子模型设计了系列用于制作引线框架的Cu-Ni-Si合金。在Cu含量小于95%的浓溶质区,采用单团簇模型[(Ni2/3Si1/3)-Cu12]Cu1~6设计合金成分;在Cu含量大于或等于95%的稀溶质区,采用双团簇模型{[(Ni2/3Si1/3)-Cu12]Cu3}A+{[Cu-Cu12]Cu3}B设计合金成分。利用XRD、OM、TEM、Vickers硬度计、电导率测量仪等实验获得Cu-Ni-Si合金的成分规律。结果表明,在Cu-Ni-Si合金的成分范围内存在Cu含量为95.0%~95.8%的成分敏感区,此区间内合金同时存在时效析出强化和调幅分解强化,致使Vickers硬度突然增加,导电率降低,两者变化趋势相反,且与成分之间无规律性依赖关系。成分敏感区前后的浓溶质区和稀溶质区的合金中,不存在调幅分解强化,Vickers硬度(H)随Cu含量(CCu)增加而减少,分别满足H=-12.6CCu+1362.7和H=-26.2CCu+2777.3的线性关系;相应的导电率(σ)随CCu的线性增加关系分别为σ=0.2CCu+28.6和σ=5.2CCu-466。
Cu-Ni-Si alloys are among the most widely used electrical conductive(>30%IACS) alloys with quite high strength level(>500 MPa), so they are especially suitable for lead frames and connector joints. However, these two properties are quite composition sensitive, apart from their tight connection with processing. Moreover, their compositions fall within quite broad ranges that poses difficulties for the industries. For instance, typical C7025 alloy has a specified composition(mass fraction,%) range of Ni2.2~4.2, Si 0.25~1.2, Mg 0.05~0.3, plus less than 0.5 of other impurity elements. Obviously the composition ranges of the elements are far from even their absolute contents. The present work focuses on understanding the composition rule of Cu-Ni-Si via a new structural tool, the cluster-plus-glue-atom model. In this model, any solid solution is described by a nearest neighbor coordination polyhedron plus a one-tosix glue atoms. Specifically for Cu-based alloys, the cluster is cubooctahedron. The composition formulafor solute-rich Cu-Ni-Si alloys and pure Cu are established, respectively [(Ni2/3 Si1/3)-Cu12]Cu1~6 and[Cu-Cu12]Cu3. A series of Cu-Ni-Si alloys were designed on the basis of the cluster-plus-glue-atom model.In the concentrated solute region with Cu content less than 95%, the alloys were designed using the single cluster model [(Ni2/3 Si1/3)-Cu12]Cu1~6. In the dilute solute region where Cu content is larger than or equal to 95%, the alloys were designed using the double cluster model {[(Ni2/3 Si1/3)-Cu12]Cu3}A+{[Cu-Cu12]Cu3}B.The alloys were arc-melted into ingots under Ar atmosphere and were subjected to a solution treatment at 950 ℃ for 1 h plus water quenching, and then to an ageing at 450 ℃ for 4 h plus water quenching. The microstructure and properties of the alloys were characterized and tested by XRD, OM, TEM, Vickers hardness tester and digital metal conductivity instrument. The composition rule of the designed Cu-Ni-Si alloy was obtained by experiments.The results shown a special range of Cu content in 95.0%~95.8% as a composition sensitive region, in which, in addition to ageing precipitation strengthening, the alloys also have amplitude modulated decomposition strengthening, resulting in a sudden increase in Vickers hardness and a decrease in electrical conductivity. Vickers hardness and electrical conductivity change with composition variations in an irregular manner. In the concentrated and dilute solute region before and after the composition sensitive region, Vickers hardness(H) is linearly related to the Cu content(CCu) by H=-12.6 CCu+1362.7 and H=-26.2 CCu+2777.3, and the corresponding electrical conductivity(σ) is also linearly related to the CCuby σ=0.2 CCu+28.6 and σ=5.2 CCu-466.
作者
李冬梅
姜贝贝
李晓娜
王清
董闯
LI Dongmei;JIANG Beibei;LI Xiaona;WANG Qing;DONG Chuang(Key Lab of Materials Modification by Laser,Iron and Electron Beams (Ministry of Education),School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China;School of Mechanical Engineering,Inner Mongolia University For Nationalities,Tongliao 028000,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第10期1291-1301,共11页
Acta Metallurgica Sinica
基金
国家重点研发计划项目No.2017YFB0306100
国家自然科学基金项目No.11674045~~
关键词
CU-NI-SI合金
成分规律
硬度
导电率
成分敏感区
Cu-Ni-Si alloy
composition rule
hardness
electrical conductivity
composition sensitive region
作者简介
李冬梅,女,1973年生,博士生;通讯作者:董闯,主要从事合金相成分设计等的研究,E-mail:dong@dlut.edu.cn.
