因瓦合金纳米抛光材料去除机理的分子动力学模拟

As a unique kind of low-expansion materials, Invar alloy has been widely used in high-tech fields, such as aerospace, but few studies are conducted on its ultra-precision machining theory and technology. Among them, nano-polishing is an important method for ultra-precision machining of Invar alloy. Aiming at showing the material removal mechanism of Invar alloy in the nano-polishing process, the influence of polishing speed on the material removal rate, subsurface damage and the smoothness of polished surface is studied based on molecular dynamics simulation. Specifically, through the analysis of polishing chip, energy, polishing force and dislocation movement, the deformation and damage mechanism of Invar alloy is revealed. It is shown that the material removal rate will reach a critical value as the polishing speed increases. When the velocity increases, the grinding heat promots nucleation of dislocations, and therefore the subsurface damage thickness increases. However, with the velocity over than 100 m/s, the drastically increased strain rate leads to the limitation of dislocation movement, which reduces the thickness of subsurface damage. This paper enriches the theoretical understanding and provides technological references for realizing the high efficiency and low damage machining mechanism of Invar alloy.