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-1T-1) m4J-1s-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.
Bibliographische NotizFunding Information:
The authors gratefully acknowledge the financial support under the scope of the COMET program within the K2 Center “ Integrated Computational Material, Process and Product Engineering (IC-MPPE) ” (Project No 859480 ). This program is supported by the Austrian Federal Ministries for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK) and for Digital and Economic Affairs (BMDW) , represented by the Austrian research funding association (FFG) and the federal states of Styria, Upper Austria and Tyrol. This research was also partially supported by the Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea ( NRF-2022H1D3A2A01081708 ).
© 2023 Acta Materialia Inc.