The Interface Structure Of Amorphous Alloy During Solidification And Thermodynamic Characteristics

Phase transition of liquid-solid is a common phenomenon in nature. The liquid-solid interface has a high degree of complexity and dynamic variability in the process of alloy's solidification, which often behaves in non-equilibrium and nonlinear. The existence of the interface has a significant impact on the thermodynamic properties of the interfacial region as well as its motion, transportation and chemical reaction.This paper based on the microstructure of supercooled liquid and the movement of atoms in it, GEAM potential function is used to describe the interaction force between atoms by molecular dynamics simulations, pair correlation function, mean square displacement (MSD) and other analytical methods, are used to study the solidification process of amorphous alloy Cu66Ti34 under different conditions. At the same time, amorphous alloy Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 was prepared by water quenching and characterized by using scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry.Solidification processes of Cu66Ti34 alloy melt from 1600K to 300K at cooling rate 4×1011 K/s and 4×1013 K/s are studied, showing that amorphous is formed in the 4×1013K/s cooling rate, glass transition temperature was 600K. In the beginning stage of solidification, the binding force is same, so that the interface is flat, after some time, the binding force is different, show a non-planar interface, which can be seen from the MSD images. At the 4×1011 K/s cooling rate, part of the melt is crystallized at 800K. Diffusion ability of particles at the 4×1011 K/s cooling rate is bigger than that of at 4×1013K/s, solidification rate decrease two orders of magnitude, while the MSD increases two orders of magnitude, which indicate that with lower solidification rate and longer solidification time, the particles have enough time for rearrangement and migration.Amorphous alloy was made by water quenching method, showing that the interface of amorphous alloys, at first, was smooth, then developed to paste state. In the water quenching conditions, the quartz tube as well as quartz tube and heat the reaction layer of liquid metal state determine the rate of solidification. Enthalpy, internal energy and volume vs temperature was obtained in the simulation process. The specific heat of the alloy is calculated, which distributed in secondary order vs temperature at 4×1013K/s cooling rate, Tg calculated by dynamic properties was closer to experimental results.