How Local Stress Governs the Flow of Metallic Liquids at High Temperatures

Understanding how local structures govern relaxation dynamics of liquid metals is a central challenge in the physics of liquids. While the connection between viscosity and collective dynamics has been widely studied, the role of local stress states in controlling local relaxation remains poorly understood, particularly across different materials. Here, we employ molecular dynamics simulations to decompose the shear-stress autocorrelation function into atomic contributions for three model liquid metals: Zr50Cu50，Pd82Si18，Fe. We find that local shear relaxation times are strongly correlated with local pressure and von Mises stress for all systems studied. The results show that atomic sites under compression are more unstable against shear than those under tension, leading to faster relaxation of local shear stress. We also find that atomic sites with large von Mises stress relax the stress more rapidly. When expressed in terms of local volume or shear strain, the local relaxation times scaled by average relaxation time collapse onto temperature- and materialindependent linear relations, revealing a universal structure–dynamics relationship. A combined analysis of pressure and von Mises stress shows that atomic sites under high compression and large von Mises stress relax nearly twice as fast as those under tension with small von Mises stress, indicating pronounced spatial heterogeneities in local dynamics. These results establish local stress analysis as a powerful framework for linking local structure to local dynamics in liquids.