基于同步辐射X射线成像液/固复层界面氢气泡的形核、生长演变与运动行为的原位研究

In Situ Study on the Nucleation,Growth Evolution,and Motion Behavior of Hydrogen Bubbles at the Liquid/Solid Bimetal Interface by Using Synchrotron Radiation X-Ray Imaging Technology

利用同步辐射X射线二维成像技术对液/固复层界面加热过程中氢气泡的生长、运动行为及形态演变进行了原位表征,研究气泡的形核机理、生长机制与运动特征。结果表明,氢气泡的形核机制主要为非均质形核与双层表面膜演变;成分不均匀与双层膜转变将群体气泡的生长分为2个不同阶段,气泡平均尺寸与时间的变化关系遵循stochastic随机模型;其生长机制为跳跃合并与熟化吞并机制,伴随着氢气泡形态由球状向椭球状与非规则状转变;氢气泡的运动包含向上迁移与无定向跳跃,在金属间化合物阻碍下氢气泡的生长经历多次跳跃,主要归因于双层表面膜转变为气泡、变形气泡尺寸增加、化合物溶解与化合物的扰动。

Pore defects at the liquid/solid interface contribute to the interfacial bonding quality.Understanding the formation and growth mechanism of pores can help control their size distribution and eliminate their formation.However,the traditional static-research methods limit the in-depth study of the dynamic evolution behavior of bubbles.The growth,motion behavior,and morphological evolution of hydrogen bubbles at the liquid/solid bimetal interface during heating were characterized in situ,using synchrotron radiation X-ray imaging technology,and the bubbles’nucleation,growth mechanisms,and motion characteristics were investigated.The results show that the nucleation mechanism of hydrogen bubbles contains heterogeneous nucleation and bifilms.Bubble growth is divided into two stages:the inhomogeneous composition and bifilm transformation into hydrogen bubbles.The relationship between the bubbles’mean diameter and heating time conform to the stochastic model.The growth mechanism of bubbles exhibits jump merging and annexation behaviors,accompanied by the morphological transformation from spherical to elliptic and irregular shapes.The motion of the hydrogen bubbles includes upward migration and astatic jumping.The bubbles’growth,hindered by intermetallic compounds(IMCs),has experienced several jumps,attributed to the transformation of bifilms into bubbles,increasing bubble size and deformation,IMC dissolution,and IMC disturbance.