为了研究熔融Mg-Zn-Al合金与镁基母材钎焊过程中的界面扩散行为及超声辅助下振动参数对钎焊效果的影响规律，本工作构建了Mg/Mg-Zn-Al界面原子模型，采用分子动力学方法在纳米尺度模拟计算了温度和超声参数对Mg/Mg-Zn-Al界面扩散行为的影响，讨论了超声辅助对界面力学性能的影响，并对超声辅助Mg/Mg-Zn-Al钎焊界面的温度和应变率响应进行了分析。结果表明，超声辅助的引入使体系扩散系数增大5~10倍，结合层厚度增大2.5~7.6倍，所需钎焊温度也大幅降低。相较于超声振幅，增大超声频率会加快界面趋衡速率，从而得到厚度更大、分布更均匀的界面结合层。在力学性能方面，在振幅0.2 nm、频率1000 GHz条件下，超声辅助钎焊界面拉伸强度较高温钎焊界面提高11.5%。多种加载条件下界面的力学行为对比模拟结果表明，相较于应变率，钎焊界面力学性能对温度更为敏感。在高温条件下，最大拉伸应力的应变率敏感度更高。

Magnesium alloys are characterized by low density, high specific strength, high specific modulus, and excellent heat dissipation, which have garnered increasing attention from both academia and industry. Brazing, as a metal and alloy joining technique, is highly valued for its stability in forming and its ability to preserve the microstructure and properties of the base metal. However, due to magnesium's high chemical activity, low melting point, high thermal and electrical conductivity, and tendency to oxidize easily, selecting and designing suitable solder for the brazing process present significant challenges. The Mg-Zn-Al alloy, with its low melting point and composition matching the base metal, is considered a suitable filler metal for brazing magnesium alloys. To study the interfacial diffusion behavior of the molten Mg-Zn-Al alloy during the brazing of Mg-based metals and the influence of the ultrasonic-assisted vibration parameters on the brazing process, a Mg/Mg-Zn-Al interface molecular model was constructed to study the microscopic mechanisms involved. The diffusion behavior at the Mg/Mg-Zn-Al interface was simulated using molecular dynamics on the nanoscale, exploring how ultrasonic assistance on the mechanical properties of the interface, including an analysis of the temperature and strain rate response at the brazing interface under ultrasonic assistance. The results show that ultrasonic assistance increases the diffusion coefficient of the system by 5-10 times and the thickness of the bonding layer by 2.5-7.6 times, significantly lowering the required brazing temperature. Furthermore, while both ultrasonic frequency and amplitude enhance interface equilibrium, increasing the ultrasonic frequency leads to a thicker and more uniformly distributed bonding layer. In terms of mechanical properties, the tensile strength of the ultrasonic-assisted brazing interface, with an amplitude of 0.2 nm and a frequency of 1000 GHz, is 11.5% higher than that of a high-temperature brazing interface. Meanwhile, compared with the mechanical behavior of the interface under various loading conditions, the mechanical properties of the brazing interface are more temperature-sensitive than strain-rate-sensitive, with high-temperature conditions amplifying strain-rate sensitivity for maximum tensile stress.