Regensburg 2022 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 6: Computational Materials Modelling: Defects / Alloys
MM 6.8: Talk
Monday, September 5, 2022, 17:45–18:00, H44
strong impact of spin fluctuations on the antiphase boundary energies of weak ferromagnetic Ni3Al — •Xiang Xu1,2, Xi Zhang2, Andrei Ruban3,4, Siegfried Schmauder1, and Blazej Grabowski2 — 1Institute for Materials Testing, Materials Science and Strength of Materials, University of Stuttgart, Germany — 2Institute for Materials Science, University of Stuttgart, Germany — 3KTH Royal Institute of Technology, Stockholm, Sweden — 4Materials Center Leoben Forschung GmbH, Leoben, Austria
The antiphase boundary (APB) was believed to be crucial for explaining the anomalously increased yield stresses of L12 Ni3Al. However, an accurate temperature-dependent APB energy is still missing and the magnetic effect was often underestimated or even neglected. In this work, the influence of longitudinal spin fluctuations (LSF) as well as other thermal mechanisms were considered within the ab-initio framework up till the melting point. We found that the calculated T-dependent APB energies show a remarkable agreement with the experimental data despite the large discrepancy between different works. The LSF effect was determined to crucially increase APB energies, especially for (100)APB with a maximum of 50% over the nonmagnetic data. This significant contribution prompts to take serious consideration of LSFs when studying the paramagnetism, even for weak itinerant ferromagnetic materials. The accurate APB energy acquired in this work can be used to set up quantitative models for simulating dislocation motions and the elastic-plastic behavior for Ni-based superalloys on the macro scale.