铁基非晶合金快速局部加热钎焊润湿行为和界面反应及接头可靠性研究

High reliability joining of the amorphous alloy to itself or to other metallic materials has been a key issue and challenge for further applications of the amorphous alloy. This project proposal aims to study the solderability of Fe-based amorphous soft magnetic alloys by lead-free soldering process using rapid localized heating, and clarify the influence of the soldering process on the joint reliability (the amorphous phase stability of the alloys). The interfacial reaction and wetting behavior of the tin-based lead-free solders on Fe-based amorphous soft magnetic alloys of different microstructures will be characterized by sessile drop method; and the influence of microstructural feature, structural relaxation and the crystallization of the amorphous alloy on the interfacial reaction and wettability of the solder will be clarified. The microstructural characteristics at the wetting interface will be investigated by transmission electron microscope (TEM) and selected area electron diffraction (SAED) analysis, and the thermodynamics and kinetics correlation between the microstructural characteristics of the base alloy and wettability of the solder will be established. The interfacial reaction mechanism between the amorphous alloy and the solder, the change of the amorphous state of the alloy in vicinity of the joint and the mechanical behavior/magnetic performance of the joint will be studied by using sophisticated microanalysis and characterization approaches, such as electron microscopic analysis, differential scanning calorimetry (DSC) and dynamic mechanical analysis. The influence of wetting, interfacial reaction and the thermal cycle in soldering process on the amorphous state stability of the alloy and joints' properties will be identified; and the key issues affecting the solderability of the amorphous alloy, such as the material factor and processing factor, will be elucidated. In the completion of the project, it is envisaged that the outcomes of the study would provide theoretical background for high reliability joining of Fe-based amorphous alloys,and further enrich and develop the process theory for soldering advanced metallic materials.

实现非晶合金自身或与其它金属材料的高可靠性冶金连接是拓展该类新型金属材料应用的关键问题之一。本项目针对具有优异软磁性能的铁基非晶合金开展快速局部加热软钎焊性及接头可靠性（非晶稳定性）的研究；采用座滴法研究锡基无铅钎料在所制备的不同微观结构特征的非晶合金上的反应润湿行为，阐明非晶合金微区结构特征和结构弛豫及晶化等对润湿性和界面反应的影响；采用透射电镜选区电子衍射法确定润湿界面微区结构特征，建立基材微观结构与润湿性之间的热/动力学关系；利用电子显微分析、差热分析和力学性能评价等表征方法研究非晶合金与钎料之间的界面反应机理、钎焊区域微观组织演变及相应接头的力学和磁性能，揭示润湿和界面反应及热历程对钎焊区域非晶稳定性和接头可靠性的影响机制，阐明影响非晶合金钎焊的内因（材料）和外因（工艺及参数）及其作用规律，为实现铁基非晶合金的高可靠性连接提供技术基础支持，并丰富和完善先进金属材料的钎焊工艺理论。

实现非晶合金自身或与其它金属材料的高可靠性冶金连接是拓展该类新型金属材料应用的关键问题之一。本项目针对具有优异软磁性能的铁基非晶合金开展快速局部加热软钎焊性的研究，采用座滴法研究几种典型软钎料（即Sn-37Pb、Sn-58Bi、Sn-0.7Cu和Sn）在非晶态合金Fe84.3Si10.3B5.4及其退火后不同微观结构合金表面的润湿行为和界面特征，然后采用高频感应加热方法研究了Sn-Cu钎料钎焊Fe基非晶合金、Fe基非晶合金与纯铜、Fe基非晶合金与纯铝（1050Al）三种不同钎焊接头的界面微观组织，为实现铁基非晶合金的高可靠性连接提供技术基础支持，并丰富和完善先进金属材料的钎焊工艺理论。.主要研究结果如下：.（1）在250℃温度保温30min时，四种钎料在非晶态Fe84.3Si10.3B5.4合金基片上的平衡润湿角从小到大排序是：Sn-37Pb＜Sn-58Bi＜Sn-0.7Cu＜Sn。观察界面形貌发现Sn-0.7Cu与非晶态Fe84.3Si10.3B5.4合金基片的界面上出现间断的化合物，综合考虑良好的润湿性和合适的界面反应，Sn-0.7Cu钎料更适合非晶态Fe84.3Si10.3B5.4合金的焊接。.（2）随钎焊温度的升高，Sn-0.7Cu钎料在非晶态Fe84.3Si10.3B5.4合金基片上的平衡润湿角逐渐减小，润湿性获得改善；Sn-0.7Cu/非晶态Fe84.3Si10.3B5.4钎焊接头界面形成的金属间化合物（IMC）由间断分布变为连续分布。.（3）随钎焊温度的升高，Sn-0.7Cu钎料在退火后不同微观结构Fe84.3Si10.3B5.4合金基片上的平衡润湿角均逐渐减小，润湿性逐渐变好，界面反应逐渐增强；在相同的钎焊温度下，Sn-0.7Cu钎料在不同退火工艺处理后具有不同微观结构Fe84.3Si10.3B5.4合金基片上的平衡润湿角随退火温度升高而逐渐增大，润湿性逐渐变差，界面反应逐渐减弱。.（4）采用高频感应加热方法对Sn-0.7Cu钎料钎焊不同材料的接头进行研究后发现：非晶态Fe84.3Si10.3B5.4合金同质接头界面不存在明显的化合物相；非晶态Fe84.3Si10.3B5.4与Cu钎焊接头处靠近非晶侧的界面存在空洞，且没有观察到明显的化合物存在，而在靠近Cu侧的界面处形成了连续的Cu6Sn5相且钎料内部弥散分布大量的长条状Cu6Sn5相；非晶态Fe8