Evolution of surface tension in strained molten aluminum: a liquid-vapor interface study.

As a key physical property determining the wettability, adsorption, and structural stability of liquid materials, surface tension is of great significance in material preparation and micro-nano processing. However, traditional methods often rely on chemical composition or temperature adjustments, and how to achieve dynamic control of surface tension under pure mechanical loads remains a frontier issue in surface physics and materials science. Especially under high-frequency extreme loads, the microscopic mechanism of the surface dynamics of molten metal is still unclear, and it is necessary to establish effective theoretical models and numerical methods to reveal it. In this case, we simulated the mechanical response characteristics of the molten aluminum metal surface system to the lateral mechanical cyclic load, and analyzed the steady oscillatory behavior of the cyclic load using the dynamic surface tension of the system. This paper demonstrates that under the 50 GHz high frequency and 5% high amplitude cyclic loading conditions, the average growth rate of the dynamic surface tension of the aluminum liquid can reach approximately 5%. The peak and valley values of the instantaneous dynamic surface tension can respectively reach 30% and 15% of the equilibrium surface tension, showing a controllable trend of significant increase in surface tension with the increase of the load. We applied the previously proposed method of quantitatively adjusting the surface tension under load action to the surface system of the aluminum liquid, and obtained the conclusion that the surface tension of the aluminum liquid can also be dynamically adjusted. This verifies the reliability and universality of this regulation strategy in metal liquids, and provides strong support for the generalized intrinsic frequency and damping constant correlation theory. The analysis of liquid layering clarifies the cross-scale correlation mechanism between macroscopic mechanical response and atomic-scale dynamics, providing new insights into the microscopic mechanism of surface behavior. The research results clarify the quantitative relationship between frequency, amplitude and the rate of surface tension change. This provides direct basis for the process optimization and parameter design of liquid aluminum in precision casting, additive manufacturing and microfluidic systems. By reasonably regulating the load conditions, active control of the surface tension can be achieved. This will enhance the scientificity and process controllability of system design in applications such as wetting adjustment, interface stability improvement and flow behavior optimization.