Nanostructure Features In The Rapid Solidification Process Of Fe₃Si

The inter-metallic compound Fe₃Si is an important magnetic functional material,which has a wide range of applications due to its high hardness,excellent corrosion resistance,low electrical conductivity and excellent soft magnetic properties.At present,there are many studies on the relatively stable DO₃ type structure in Fe₃Si,but there are few work related to microstructure features in related researches.Nanostructures are often used as the key research objects in material simulation.Molecular dynamics method is used to simulate the solidification processes of Fe₃Si under different conditions.The exploration of nanostructures will help to further understand its physical properties and provide theory guide for the application of this material.In this study,the molecular dynamics simulation of the rapid solidification process of liquid Fe₃Si at different cooling rates and different pressures was carried out using the Tersoff potential which is suitable for use in Fe₃Si system.The obtained data were analyzed in detail by means of the atomic average energy,the pair distribution function,the specific volume,the coordination number,the angular distribution function,the common neighbor sub-cluster,the standard cluster analysis and microstructure visualization.The results show that the cooling rates affect the degree of crystallization?or amorphization?of liquid Fe₃Si.The secondary phase transition of Fe₃Si occurs in the solidification at 10¹⁰ K/s.At a cooling rate of 10¹² K/s,the system is finally in a state between the crystalline state and the amorphous state,and when different pressures are applied at the cooling rate,the formation of the amorphous structure of the system is promoted.In this study,the relationship between the percentage of the topologically close-packed largest standard cluster and the temperature is affected by the common neighbor sub-cluster S555.At 30GPa,there are some S555 and topologically close-packed largest standard clusters in the solidified Fe₃Si,and the percentage of them reached the maximum.For the system under 2GPa,the solidified Fe₃Si has a large number of nanostructures[8/300],which is in a low-energy steady state with a higher medium-range ordering degree.The different size medium-range ordered structures related to[8/300]mainly form larger-sized amorphous by the mosaic of two kinds of nanostructures[2/200,6/300]and[6/200,4/300].In addition,these three kinds of nanostructures are easy to form long chains of non-long range order with other Fe atoms,and form locally compact short chains with Si atoms in the system.These long and short chains are connected to each other to improve the overall structural stability.