Regensburg 2022 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 6: Computational Materials Modelling: Defects / Alloys

MM 6.8: Vortrag

Montag, 5. September 2022, 17:45–18:00, H44

strong impact of spin fluctuations on the antiphase boundary energies of weak ferromagnetic Ni3Al — •Xiang Xu^1,2, Xi Zhang², Andrei Ruban^3,4, 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.