WCPM: Naomi Hirayama, Warwick
2025-01-13 13:00 - 14:00 | A2.05B
Location: A2.05B (there will be an informal sandwich lunch outside D2.02 at 12.30) Time: 13.00-14.00 To join this meeting online click here. Title: Theoretical Study on Local Structures in Fe-based Amorphous Alloys Abstract: Local atomic arrangements, such as short-range order and medium-range order, are crucial in determining the physical properties of amorphous materials. Direct experimental observation of these microscopic structures is challenging; nevertheless, computational approaches such as molecular dynamics simulations afford valuable insights. This study investigates Fe–Si–B amorphous alloys, recognised for their excellent soft magnetic properties, making them promising candidates for high-efficiency motor core materials. However, their challenging manufacturability has limited their widespread adoption. Addressing this issue requires a deeper understanding of the origins of their mechanical properties. In our study, melt-quench simulations were conducted using a machine learning potential based on the Gaussian approximation potential (GAP). The radial distribution functions obtained from these simulations closely matched the experimental data. The results revealed that B-centred clusters predominantly exhibit anti-prism and trigonal prism structures, while the Si-centred clusters are characterised by icosahedral and related geometries. These cluster structures formed rapidly near the glass transition temperature during quenching and subsequently coalesced into networks. The modes of connection between cluster pairs—vertex, edge, face, and multipoint sharing—were found to depend on the cluster type. The hierarchical ordering observed in these alloys should play a crucial role in understanding their mechanical behaviour. This study highlights the potential of GAP for uncovering the structural properties of amorphous alloys, offering a pathway to improve their manufacturability and broader applicability. Bio: Background · 2020–Present: Associate Professor (Next Generation Tatara Co-Creation Centre, Shimane University) · 2009–2020: Project Researcher (University of Tokyo, Osaka University, and others); Assistant Professor (Tokyo University of Science, Tokyo Metropolitan University) · March 2009: PhD in Science (Ochanomizu University, Tokyo, Japan) Research Field · Amorphous alloys: Investigation of structural and mechanical properties using machine-learning molecular dynamics simulations · Thermoelectric materials: Calculation of electronic and thermoelectric properties based on first-principles calculations.
