Dynamic Analysis of Recalescence Process and Interface Growth of Eutectic Fe 82 B 17 Si 1 Alloy
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JMEPEG (2018) 27:1784–1791 https://doi.org/10.1007/s11665-018-3269-y
Dynamic Analysis of Recalescence Process and Interface Growth of Eutectic Fe82B17Si1 Alloy Y. Fan, A.M. Liu, Z. Chen, P.Z. Li, and C.H. Zhang (Submitted August 24, 2016; in revised form February 25, 2018; published online March 12, 2018) By employing the glass fluxing technique in combination with cyclical superheating, the microstructural evolution of the undercooled Fe82B17Si1 alloy in the obtained undercooling range was studied. With increase in undercooling, a transition of cooling curves was detected from one recalescence to two recalescences, followed by one recalescence. The two types of cooling curves were fitted by the break equation and the Johnson–Mehl–Avrami–Kolmogorov model. Based on the cooling curves at different undercoolings, the recalescence rate was calculated by the multi-logistic growth model and the Boettinger–Coriel–Trivedi model. Both the recalescence features and the interface growth kinetics of the eutectic Fe82B17Si1 alloy were explored. The fitting results that were obtained using TEM (SAED), SEM and XRD were consistent with the changing rule of microstructures. Finally, the relationship between the microstructure and hardness was also investigated. Keywords
eutectic Fe82B17Si1 alloy, growth kinetics, recalescence rate, undercooling
1. Introduction Alloy solidification has industrial significance and has received considerable attention from the scientific community (Ref 1, 2). For predicting mechanical properties, solidification kinetics, which is used to determine the microstructure of metallic castings, needs to be understood. Over the past few decades, a number of researchers have developed multiple theories to predict the solidification velocity of pure metals and alloys (Ref 3, 4). To develop a qualitative description of alloy solidification and a numerical model, the solidification kinetics of diluted Ni-B, Ni-C, Ni-Ti and Ni-Sn alloy systems was used (Ref 5-7). The solidification velocity data and the solidification structure were used to develop a description of alloy solidification kinetics. Because of the large nucleation rate and the low growth rate, a refined microstructure can be obtained from the undercooled melts (Ref 1-5). Furthermore, re-melting and fragmentation resulting from the recalescence and convection in the melt favor the formation of a fine microstructure (Ref 8). As one of the simplest metal–metalloid ternary eutectic alloys, FeBSi ternary eutectic alloys have been studied because of their soft magnetic properties (Ref 9, 10). To obtain and to finally control the refined microstructure of the FeBSi alloy, the microstructure evolution and phase formation mechanism needs to be understood. Using melt fluxing, the microstructure formation from small FeBSi molten droplets was studied by Zhang et al. Y. Fan, Z. Chen, and P.Z. Li, School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221008 Jiangsu, Peoples Republic of China; A.M. Liu and C.H. Zhang, School of Mechanical an
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