Simulation On Rapid Solidification And Microstructure Analysis Of Magnetic Material FeNi Alloys

This article briefly summarizes the solidification of liquid metal alloys,the properties and application status of magnetic materials Fe Ni alloys,introduces in detail rapid solidification technology,molecular dynamics methods and microstructure characterization methods,and focuses on simulating the rapid solidification process of liquid Fe Ni alloys under different conditions,so as to further study the solidification law and microscopic evolution mechanism of the alloys.Firstly,molecular dynamics simulations on the rapid solidification process of liquid Fe₈₀Ni₂₀alloy under different cooling rates is conducted.The research indicates that the microstructure of solidification is different under the four cooling rates,corresponding to different transition temperatures.The critical cooling rate of Fe₈₀Ni₂₀alloy solidified into crystal is in the range of 10¹¹K/s to 10¹⁰K/s.Moreover,compared with the amorphous,the Fe₈₀Ni₂₀crystalline system has lower energy and configuration entropy.The cooling rates not only make the alloy form crystalline and amorphous separately,but also quantitatively cause the difference in the microstructure of the system.Secondly,the simulation on the rapid solidification process of liquid Fe_xNi_?100-x??x=10,20,30,40,50,60,70,80,90?alloys has been conducted to investigate the crystallization mechanism.The results show that at the cooling of 10¹¹K/s,Fe₁₀Ni₉₀,Fe₂₀Ni₈₀,Fe₃₀Ni₇₀and Fe₉₀Ni₁₀are rapidly cooled into crystalline solids.The effect of composition of alloys on chemical order of liquid is rather weak,while stronger on solids and Fe₂₀Ni₈₀has the relative strongest chemical order.Among the Fe₁₀Ni₉₀alloy,five-fold symmetrical grain boundaries including truncated decahedron atoms hamper the hcp?fcc transition due to their different orientations.But the parallel grain boundaries in Fe₃₀Ni₇₀alloy is easy covert,resulting in a pathway of supercooled-liquid??fcc+hcp??fcc states,crystallization is accompanied with the reduction in the number of cluster kinds,the average potential energy,and the structure entropy.In addition,the transformation process of crystal structures at the atomic scale is unveiled by employing the tracing method.These findings will significantly advance the understanding on the crystallization of liquid alloy as well as other metals.Finally,the rapid solidification process and the amorphous law of microstructure on five liquid alloys Fe_xNi_?100-x??x=40,50,60,70,80?are simulated,and it is further found that the five alloy systems are solidified into amorphous solids,which have a similarity in the medium-range order,and the corresponding glass transition temperature has a nonlinear relation with the composition.When Fe Ni amorphous alloys solidify,the most obvious cluster growth is Z12 in TCP structures,but the high content of Ni may have an inhibitory effect on TCP structures,and the Fe₄₀Ni₆₀alloy has the least TCP structures.The influence of element content on amorphous alloys is also reflected in the central atom of TCP structures,which is mainly Ni and Fe in Ni-rich and Fe-rich alloys,but slightly more Ni in Fe₅₀Ni₅₀alloy.Among amorphous alloys,Fe₄₀Ni₆₀with the strongest chemical order has the lowest energy and the most stable structure.