La元素对高导热Al-5Ni合金微观组织和性能的影响

Effect of La element on microstructure and properties of high thermal conductivity Al-5Ni alloy

Al-5Ni合金具有较高的导热性能,是新一代高导热材料的主要研究方向之一,但力学性能偏低,热-力矛盾显著。利用金相显微镜、扫描电镜、万能试验机、激光导热仪、数字电导率仪等,研究了微量稀土元素La添加对高导热Al-5Ni合金微观组织、力学性能及导热率和导电率的影响。结果表明,当La元素的添加量为0.2%(质量分数)时,合金α-Al晶粒细化程度最高,共晶组织内部纤维状的Al3Ni相近乎全部转化为球状,极限抗拉强度和硬度由未变质时的122.24 MPa和45.94 HV提升到140.48 MPa和47.28 HV,分别提升了14.92%和2.92%;合金的导热率和导电率几乎没有下降,为213.23 W/(m·K)和31.84 MS/m。稀土变质La元素的变质处理有效缓解了Al-5Ni合金的热-力矛盾,显著提高合金的综合性能。

Al-5Ni alloy has high thermal conductivity and is one of the main research directions for the new generation of high thermal conductivity materials.However,its mechanical properties are relatively low,and the thermal-mechanical contradiction is significant.The effects of trace rare earth element La addition on the microstructure,mechanical properties,thermal conductivity and electrical conductivity of high thermal conductivity Al-5Ni alloy were studied using metallographic microscope,scanning electron microscope,universal testing machine,laser thermal conductivity meter,and digital conductivity meter.The results indicate that after adding 0.2%(mass fraction)La element,the refinement degree of alloyα-Al grains is the highest,and the fibrous Al 3Ni phase inside the eutectic structure is almost completely transformed into spherical.The ultimate tensile strength and hardness have increased from 122.24 MPa and 45.94 HV before modification to 140.48 MPa and 47.28 HV,an increase of 14.92%and 2.92%;the thermal conductivity and electrical conductivity of the alloy have hardly decreased,reaching 213.23 W/(m·K)and 31.84 MS/m.The modification treatment of rare earth La element effectively alleviates the thermal-mechanical contradiction of Al-5Ni alloy and significantly enhances the overall performance of the alloy.