Atomistic simulation of diffusion bonding of dissimilar materials undergoing ultrasonic welding
Atomistic simulation of diffusion bonding of dissimilar materials undergoing ultrasonic welding
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DOI：
10.1007/s00170-019-03582-9
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
A. Samanta;S. Xiao;N. Shen;Jingjing Li;Hongtao Ding
中科院分区：
文献类型：
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作者：
A. Samanta;S. Xiao;N. Shen;Jingjing Li;Hongtao Ding
超声波焊接（UW）工艺能够以低功耗为轻质金属合金创建高效的固态接头。在此过程中，观察到一个明显的扩散层，在高温下经历严重的塑性变形的接头界面处。本文提出了一种多尺度方法来预测异种材料超声焊接过程的扩散行为。该方法结合分子动力学和经典扩散理论计算焊接界面扩散层厚度。首次建立了考虑横向超声振动影响的分子动力学模型来模拟扩散层的演变。在原子水平上的超声振动的效果被假定为提供热能的关节界面和原子的机械运动。在超声振动过程中的正弦速度变化的影响被纳入通过数值积分的扩散率在不同的超声速度的时间。模拟结果表明，固相扩散系数与温度、压力和横向声速有关。较高的温度、压力和超声速度导致较高的扩散率，从而导致较大的扩散层厚度。本文提供了一个全面的审查扩散连接的行为及其依赖于工艺变量。提出了一种结合分子动力学和分层多尺度计算的数值方法来预测异种材料超声焊接过程中的扩散层厚度。
Ultrasonic welding (UW) process offers the ability to create highly efficient solid-state joints for lightweight metal alloys with low power consumption. During the process, a distinct diffusion layer is observed at the joint interface that undergoes severe plastic deformation at elevated temperature. A hierarchical multiscale method is proposed in this study to predict the diffusion behavior of the UW process of dissimilar materials. The method combines molecular dynamics and classical diffusion theory to calculate the thickness of the diffusion layer at the welded interface. A molecular dynamics model is developed for the first time that considers the effect of transverse ultrasonic vibration to simulate the evolution of the diffusion layer. The effect of ultrasonic vibration at the atomic level is assumed to provide thermal energy at the joint interface and the mechanical movement of atoms. The influence of sinusoidal velocity change during ultrasonic vibration is incorporated by numerically time integrating the diffusivity at different ultrasonic velocity. The simulation result shows that the solid-state diffusivity depends on temperature, pressure, and transverse ultrasonic velocity. Higher temperature, pressure, and ultrasonic velocity result in higher diffusivity leading to larger diffusion layer thickness. This article provides a comprehensive review of the diffusion bonding behavior and its dependence on process variables. It also presents a numerical approach combining molecular dynamics and hierarchical multiscale calculation to predict the diffusion layer thickness for the UW process of dissimilar materials.