电镜原位电子束辐照下Au_(85) Sn_(15)纳米线的动态熔化过程（英文）

Dynamic melting process of individual 1D Au_(85) Sn_(15) nanosolders induced by electron beam irradiation in-situ HRTEM

金锡合金焊料由于其良好的性能逐渐成为一种可能替代锡铅焊料的无铅焊料,并且利用电子束辐照的焊接方式,一维金锡纳米线已经成功用于TiO_2纳米线的焊接,这为钛基半导体氧化物纳米材料的焊接提供了实验经验。然而,金锡焊料在电子束焊接时的熔化机制和动态过程的研究还很贫乏。在本文中,我们通过电化学沉积的方法制备了一维Au_(85) Sn_(15)合金纳米焊料,并详细地研究了在透射电镜中的电子束辐照下,其形貌,晶体结构,化学元素分布的演化过程,并进一步探究了电子束辐照熔化纳米焊料的机理。研究发现,在电子束辐照下,一维Au_(85) Sn_(15)合金纳米焊料的形貌由线状熔化为液滴状;其晶体结构由AuSn和Au_5 Sn为主,少量Au,β-Sn,SnO_2的混合相转化为单一的Au_5 Sn相;其化学元素在电子束辐照下发生质量损失,该过程既有物理相变又有化学相变。在电子束辐照传递的能量作用下,原子的流动或扩散迁移和重新排列是形成新的结合层的动力学机制。该工作不仅为应用纳米焊料进行电子束焊接提供了实验依据,而且为电子束辐照熔化金锡纳米合金纳米焊料的内在机制的研究提供了宝贵经验。

In this work,we have synthesized individual 1D Au_（85） Sn_（15） nanosolders with a low melting point and studied the evolution of their morphology,microstructure,chemistry,and phase changes induced by electron beam irradiation in situ transmission electron microscopy（ TEM） for the first time. The measurements show that individual 1 D Au_（85） Sn_（15） nanosolders is composed of five phases,which are Au Sn,Au_5Sn,Au,β-Sn and SnO2. The multi-phases can be transformed into a nearly homogeneous Au_5Sn phase under the irradiation of electron beam. The melting process is a combined transformation of chemical and crystal phases. Dynamical observation of their melting process at the lattice resolution in situ high-resolution TEM reveals that a liquid molten ball is quickly formed in the initial moment and then swallow the rest of single 1 D Au85 Sn15 nanosolder section by section. Our work is believed to provide a new glance at the intrinsic melting mechanism of the 1D Au85 Sn15 nanoscale solders under electron beam irradiation,which is essential for future nano-scale welding techniques.