激光粉末床熔融增材制造高导热银-铜异种金属界面的微观组织和显微硬度研究

Microstructure and Microhardness of Interfaces of High Thermal Conductivity Ag-Cu Dissimilar Metals Fabricated by Laser Powder Bed Fusion Additive Manufacturing

银和铜由于其优异的高导电和导热(HETC)特性,被广泛应用于智能电子、可穿戴设备、医疗等关键领域。激光粉末床熔融(LPBF)技术是一种高精度制造异种金属部件的创新技术,拓展了银-铜在新兴高科技领域的应用。本研究采用LPBF技术成功制备无宏观缺陷的Ag7.5Cu/Cu10Sn/Ag7.5Cu银-铜异种金属样件,探究了Ag7.5Cu/Cu10Sn(A/C)和Cu10Sn/Ag7.5Cu(C/A)界面的微观组织对显微硬度的影响。研究发现,高导热基底增强了A/C和C/A界面结合区的熔池流动,减少了孔隙与裂纹缺陷,提高了界面结合强度。界面结合区的梯度晶粒阻碍了微裂纹的扩展,有利于减少裂纹缺陷,晶粒的各向同性使两个界面都具有良好的宏观力学性能。A/C界面更强烈的马兰戈尼对流形成了更宽的结合区,促进了元素的广泛迁移,减少了宏观偏析,使结合区的平均硬度(183.34HV)高于C/A界面的(134.27HV)。本研究为LPBF制备HETC异种金属提供了理论指导和工艺参考。

Ag and Cu are widely used in key fields such as smart electronics,wearable devices,and healthcare due to their excellent high electrical and thermal conductivity(HETC)properties.The laser powder bed fusion(LPBF)technology is an innovative technology for high-precision manufacturing of dissimilar metals,which can expand the application of Ag-Cu in the emerging high-tech fields.In this study,we have pioneered the successful fabrication of Ag7.5Cu/Cu10Sn/Ag7.5Cu dissimilar metal samples without macroscopic defects using LPBF technology.The effect of microstructure on microhardness of the Ag7.5-Cu/Cu10Sn(A/C)and Cu10Sn/Ag7.5Cu(C/A)interfaces is investigated.The results show that the high thermal conductivity substrate promotes the molten pool convection in the A/C and C/A interface fusion zones,which can help reduce the porosity and crack defects and improve the interface bonding strength.The gradient grain in the fusion zone prevents the propagation of the microcracks,and facilitates the reduction of crack defects.The isotropy of the interface results in a good combination of macroscopic mechanical properties for the both interfaces.The more intense Marangoni convection at the A/C interface causes a wider fusion zone,which promotes the extensive elemental migration and reduces the macroscopic segregation,and makes the average hardness(183.34HV)in the fusion zone higher than that(134.27HV)at the C/A interface.This study provides theoretical guidance and process reference for the fabrication of HETC dissimilar metals by LPBF.