Liquid And Amorphous Al <sub> 94-x </ Sub> Ni <sub> 6 </ Sub> La <sub> X </ Sub> Alloy Structure Ab Initio Molecular Dynamics Simulations

A194-xNi6Lax amorphous alloy with random close packed structure and non-directional metallic bonding, is the ideal model material for the study of amorphous materials. Because of its extremely good physical properties such as high strength and high flexibility, it has a broad application prospects in industry. It has been the goal of the researchers, how to control the content of each component for the more easily formation of amorphous alloys. The study for the physical structure under the different components of the alloy, is of great significance for its large-scale production.Because the behavior of alloy after cooling has a significant relation to its thermal history, liquid and amorphous alloys Al94-xNi6Lax (x=3-9) were simulated by ab initio molecular dynamics, which is based on density functional theory and the supercell model. We can get the pair correlation function, coordination number, mean square displacement and other information from the simulation results. We analysed the total pair correlation function, total coordination number, partial pair correlation function and partial coordination number one by one. The result is in agreement with the known experimental results.Simulation results show that the alloy emerged completely long-range disordered structure at high temperature. This is not surprising. The system obtained under quenching didn't crystallize, but showed amorphous characteristics. The structure of amorphous alloys is similar to the structure of liquid alloys, but only short-range ordering has been enhanced. Consequently, we can approximately describe the amorphous nature with the liquid structure. By the mean square displacement analysis of high temperature system, we can find that with the increase of La atoms, the diffusion coefficient of the whole system become smaller and the system liquidity deteriorated. This is because that La atom has a large radius and big quality. The increase of La atoms prevented the diffusion of other atoms in the system, resulting in decreased diffusion coefficient. In the process of quenching, the system has no time to reach steady state corresponding to its temperature, leading to the metastable amorphous structure. It is also due to the addition of La atoms.