Transition from Crystal to Metallic Glass and Micromechanical Property Change of Fe-B-Si Alloy During Rapid Solidificati
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RAPID solidification of liquid metal is a non-equilibrium liquid/solid phase transition process that can be achieved by a high undercooling or a large cooling rate.[1,2] The drop tube with containerless processing technique can be used to comprehensively simulate the ‘‘no container, microgravity and ultra-high vacuum’’ characteristics of a space environment, which can be used to realize the combination of a large cooling rate and high undercooling. The technique provides an ideal experimental opportunity to study the new phase nucleation and phase selection in a metastable liquid phase, as well as the rapid crystal growth and microstructure evolution away from equilibrium. It is also conducive to the realization of three-dimensional rapid solidification, as well as providing another way to develop new metastable metallic materials.[3–5]
P.C. ZHANG, J. CHANG, and H.P. WANG are with the Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710072, China. Contact e-mail: [email protected] Manuscript submitted August 20, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
As important soft magnetic alloys, both Fe78Si13B9 (S1) and Fe78Si9B13 (S2) alloys have good amorphous forming ability, high saturation magnetic flux, high magnetic permeability, low loss, and other advantages. These excellent materials can be employed to prepare transformers, signal transducers, mutual inductors, magnetic recording cores, computer cores, and other electronic devices, which realize important functions, such as transfer, exchange, and storage between information and energy. These materials are widely used in many fields, such as energy, electricity, and electronics.[6,7] Because of the limitations of the application of amorphous metastable alloys, in practical applications, a method based on obtaining a nanocrystalline structure under heat treatment of the amorphous condition is used.[8,9] For many years, amorphous-nanocrystalline soft magnetic materials have been studied via various methods.[10–12] A Fe-Si-B amorphous ribbon containing Cu and Nb was annealed to obtain a special microstructure in which a-Fe(Si) particles of approximately 15 nm in size were uniformly distributed onto the amorphous matrix, which showed excellent soft magnetic properties.[13] Lu et al.[14] reported research progress for the thermal crystallization, electro/magnetic crystallization, isostatic crystallization, and thin-band continuous crystallization heat treatment of amorphous-nanocrystalline alloys.
For Fe83B17 eutectic alloy, Yang et al.[15] found that the metastable phase Fe3B was directly precipitated in competitive nucleation and maintained at room temperature when the undercooling exceeded 386 K. Zhang et al.[16] prepared bulk Fe76B12Si12 nanomaterials by using high undercooling and water quenching. It was concluded that the nanocrystalization of the solidified microstructure is due to the small growth rate of the eutectic phases, small rate of coarsening of the microstructure, low partition coefficient of the solute balance, and
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