Grain boundary mobility of γ-Fe in high-purity iron during isothermal annealing. (June 2023)

• Record Type: Journal Article
• Authors: Kern, Maximilian; Bernhard, Michael; Bernhard, Christian; Kang, Youn-Bae
• Is Part Of: Scripta materialia. Number 230(2023)
• Publication Date: 2023-06
• Subjects: Kinetics (annealing) -- HT-LSCM -- Austenite grain growth -- Grain boundary migration -- Iron; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2023.115431
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Grain boundary migration in pure electrolytic iron (Fe > 99.98 %) was studied under isothermal conditions at 1050 °C, 1150 °C, 1250 °C and 1350 °C. High-temperature laser scanning confocal microscopy (HT-LSCM) was used to observe the in-situ grain growth of austenite (γ-Fe) on the sample surface. The dependence of the arithmetic mean grain size on time and temperature were considered in a mathematical model according to classic grain growth theory. As no other effects, e.g., pinning by precipitation or impurity-induced solute drag, occur in pure Fe, the grain boundary mobility M was directly determined by fitting the experimental results. The temperature relationship followed an Arrhenius equation with M = 6.79*10 −6 *exp(-172750R −1 T −1 ) m 4 J −1 s −1 . The mobility obtained differed by more than two orders of magnitude from Turnbull's postulation, which agreed with observations in the literature. The results matched published data extrapolated from a recent study on austenite grain growth in multicomponent steels. Graphical abstract: Image, graphical abstract