Mg元素对Al-Cu-Ce共晶合金导热和力学性能的影响  

Effects of Mg Addition on Thermal Conductivities and Mechanical Properties of Al-Cu-Ce Eutectic Alloys

作　　者：李乘波 侯慧兵 刘磊磊 黄程毅 任月路[2] 杜军[1] Li Chengbo;Hou Huibing;Liu Leilei;Huang Chengyi;Ren Yuelu;Du Jun(School of Materials Science and Engineering,South China University of Technology,Guangzhou 510641,China;Guangxi Key Laboratory of Materials and Processes of Aluminum Alloys,ALG Aluminiumlnc.,Nanning 530031,China;Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization,School of Materials and Environment,Guangxi Minzu University,Nanning 530105,China)

机构地区：[1]华南理工大学材料科学与工程学院,广东广州510641 [2]广西南南铝加工有限公司广西铝合金材料与加工重点实验室,广西南宁530031 [3]广西民族大学材料与环境学院广西先进结构材料与碳中和重点实验室,广西南宁530105

出　　处：《稀有金属材料与工程》2024年第5期1385-1390,共6页Rare Metal Materials and Engineering

基　　金：广西科技基地与人才专项(桂科AD22035222);南宁市科学研究与技术开发计划项目(20221017);南宁市创新创业领军人才“邕江计划”资助项目(2021006);广西民族大学校级引进人才科研项目(2020KJQD04)。

摘　　要：以共晶型Al-14Cu-7Ce合金作为研究对象,通过调整Mg元素的添加量,探究其微观组织演变与导热和力学性能的变化规律。结果表明,铸态Al-14Cu-7Ce合金主要由α-Al和Al8CeCu4两相组成,其微观组织由粗大的共晶组织(α-Al+Al8CeCu4)构成。添加少量Mg元素可细化该共晶组织,提高其力学性能。当Mg元素的添加量为1.0%(质量分数)时,合金的屈服强度和抗拉强度分别提升至164 MPa和263 MPa,提升幅度为29%和19%,断后延伸率提升至4.5%,提升幅度为约41%,导热率为130.2 W/(m·K),下降幅度约为12%。随着Mg元素进一步添加至2.0%,合金的力学性能有所下降,其屈服强度和抗拉强度分别降至151 MPa和249 MPa,其断后延伸率降为3.9%,导热率降至108.3 W/(m·K)。合金导热率下降主要原因是固溶的Mg原子形成散射源,阻碍电子在晶格内的运动,减小了电子和声子的平均自由程。当Mg添加量达到2.0%时,Mg与Al和Cu元素发生冶金反应生成Al2MgCu相,以鱼骨状共晶组织(α-Al+Al2MgCu)形式分布于晶界处,增加合金中第二相的体积分数,进一步恶化合金的导电导热性能。而合金的力学性能下降主要由于存在(α-Al+Al8CeCu4)和(α-Al+Al2MgCu)两种共晶组织,增加相界面处微裂纹萌生的位点。综上所述,添加1.0%Mg元素可获得兼具高强度和高导热的Al-Cu-Ce共晶合金。This study focuses on the eutectic Al-14Cu-7Ce alloy to investigate the evolution of its microstructure and the changes in thermal conductivity and mechanical properties by adjusting the addition amount of Mg element.The results show that the as-cast Al-14Cu-7Ce alloy is mainly composed ofα-Al and Al8CeCu4 phases,with a microstructure consisting of coarse eutectic structure(α-Al+Al8CeCu4).The addition of a small amount of Mg element can refine the eutectic structure and improve its mechanical properties.With an addition of 1.0%Mg,the yield strength and tensile strength of the alloy increase to 164 MPa and 263 MPa,respectively,with an improvement of 29%and 19%,respectively.The elongation at break is enhanced to 4.5%,with an improvement of approximately 41%.The thermal conductivity is 130.2 W/(m·K),with a decrease of about 12%.As the Mg element content is further increased to 2.0%,the mechanical properties of the alloy decrease,with the yield strength and tensile strength decreasing to 151 MPa and 249 MPa,respectively.The elongation at break decreases to 3.9%,and the thermal conductivity decreases to 108.3 W/(m·K).The decrease in thermal conductivity is mainly due to the solid solution of Mg atoms acting as scattering centers,hindering the movement of electrons within the lattice,and reducing the average free path of electrons and phonons.When the Mg content reaches 2.0%,the Mg reacts with Al and Cu elements to form the Al2MgCu phase,which is distributed in a fishbone-shaped eutectic structure(α-Al+Al2MgCu)at grain boundaries.This increases the volume fraction of the second phase in the alloy and further deteriorates its electrical and thermal conductivity.The decrease in mechanical properties of the alloy is mainly attributed to the presence of two eutectic structures,(α-Al+Al8CeCu4)and(α-Al+Al2MgCu),which increase the initiation points of microcracks at the phase interfaces.In summary,the addition of 1.0%Mg can obtain an Al-Cu-Ce eutectic alloy with high strength and high thermal conductivity.

关 键 词：Al-Cu-Ce合金 Mg元素 导电导热性能 力学性能 

分 类 号：TG146.21[一般工业技术—材料科学与工程]