The impact of magnetic transition on Mn diffusion in α-iron: Correlative state-of-the-art theoretical and experimental study

Omkar Hegde (1) , Vladislav Kulitckii (2) , Anton Shneider (3) , Frédéric Soisson (3) , Tilmann Hickel (1) , Jörg Neugebauer (1) , Gerhard Wilde (2) , Sergiy Divinski (2, 4) , Chu Chun Fu (3)

1 Max-Planck-Institut für Eisenforschung GmbH
2 WWU - Westfälische Wilhelms-Universität Münster = University of Münster
3 SRMP - Service de recherches de métallurgie physique
4 Samara National Research University

An accurate prediction of atomic diffusion in Fe alloys is challenging due to thermal magnetic excitations and magnetic transitions. We investigate the diffusion of Mn in bcc Fe using a novel effective interaction model and first-principles based spin-space averaged relaxations in magnetically disordered systems. The theoretical results are compared with the dedicated radiotracer measurements of 54Mn diffusion in a wide temperature range of 773 to 1173 K, performed by combining the precision grinding (higher temperatures) and ion-beam sputtering (low temperatures) sectioning techniques. The temperature evolution of Mn diffusion coefficients in bcc iron in theory and exper- iment agree very well and consistently reveal a reduced acceleration of Mn solute diffusion around the Curie point. By analyzing the temperature dependencies of the ratio of Mn diffusion coefficients to self-diffusion coefficients we observe a dominance of magnetic disorder over chemical effects on high-temperature diffusion. Therefore, the missing acceleration mainly reflects an anomalous behaviour of Mn in the magnetically ordered low temperature state as compared to other transition metals.

Domains: Physics [physics]

Omkar Hegde, Vladislav Kulitckii, Anton Shneider, Frédéric Soisson, Tilmann Hickel, et al.. The impact of magnetic transition on Mn diffusion in α-iron: Correlative state-of-the-art theoretical and experimental study. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2021, 104 (18), pp.184107. ⟨10.1103/PhysRevB.104.184107⟩. ⟨cea-03602990⟩