电场对AZ31B/Al扩散结合界面结构及力学性能的影响

应用电场激活扩散连接技术(FADB)进行AZ31B与铝的固相连接,研究电场条件下结合界面快速形成的微观结构及其力学性能。采用OM、SEM、EDS及XRD等分析扩散溶解层的微观组织、成分分布和剪切断口形貌及相组成,并利用显微硬度计和微机控制电子万能试验机对接头界面扩散区显微硬度和接头抗剪强度进行分析。研究结果表明,激活电流降低扩散界面金属化合物生成的激活能,促进Mg-Al间的扩散反应,形成的梯度扩散溶解层对提高接头抗剪切强度有显著影响。在温度为450℃,时间为50 min,电流密度为80 A/cm2时,过渡层宽度达120μm,接头抗剪强度最大值35 MPa。

Influence of electric field on microstructure and mechanical properties of the diffusion joining interface of the AZ31B/Al joint

Microstructure and properties of the Mg-Al diffusion-dissolution layer in the interface of AZ31B/Al joints prepared by the field-active diffusion bonding(FADB) process were investigated.The microstructure,composition distribution of the Mg-Al diffusion-dissolution layer and phase composition of the shear fractures were analysed by means of OM,SEM,EDS and XRD.The hardness of the diffusion joint area and the shear strength of AZ31B/Al interface were analyzed.The results show that the electric field promotes the diffusion of Mg and Al elements by reducing the activation energy of formation of the intermetallic compounds.The gradient morphology of the diffusion-dissolution layer and the shear strength are affected obviously by the electric field strength and current time correspondingly.When the current density is 80 A/cm2,the thickness of the transition layer is 120 μm,and the shear strength of the AZ31B/Al interface achieves 35 MPa at 450 ℃ for 50 min.