Scientific Events

Local Phase Transformations: A New Creep Strengthening Mechanism in Ni-Base Superalloys

Polycrystalline Ni-based superalloys are vital materials for disks in the hot section of aerospace and land-based turbine engines due to their exceptional microstructural stability and strength at high temperatures. In order to increase operating temperatures and hold times in these engines, hence increasing engine efficiency and reduction of carbon emissions, creep properties of these alloys becomes increasingly important. Microtwinning and stacking fault shearing through the strengthening g’ precipitates are important operative mechanisms in the critical 600-800°C temperature range. Atomic-scale chemical and structural analyses indicate that local phase transformations (LPT) occur commonly during creep of superalloys. Furthermore, the important deformation modes can be modulated by LPT formation, enabling a new path for improving high temperature properties. [more]

High-resolution micro-plasticity in advanced high-strength steels

The persistent demand for green, strong and ductile advanced high strength steels, with a reduced climate footprint, calls for novel and improved multi-phase microstructures. The development of these new steels requires an in-depth understanding of the governing plasticity mechanisms at the micron scale. In order to address this challenge, novel numerical-experimental methods are called for that account for the discreteness, statistics and the intrinsic role of interfaces. This lecture sheds light on recent and innovative developments unravelling metal plasticity at the micron scale. Multi-phase through-thickness samples allow for a full characterization of the underlying microstructure. Using computational crystallographic insights, a slip system based local identification method has been developed, which provides full-field crystallographic slip system activity maps. The resulting deformation maps are directly used to assess the model predictions. Heterogeneous spatial variations are introduced by sampling the slip system properties of individual atomic slip planes from a probability density function. This allows to recover naturally localized slip patterns with a high resolution. It is demonstrated that this discrete slip plane model adequately replicates the diversity of active slip systems in the corresponding experiment, which cannot be achieved with standard crystal plasticity models. Recent experimental observations on dual-phase steels demonstrate substructure boundary sliding parallel to the habit plane in lath martensite, for which a habit-plane slip enriched laminate model is developed. This model adequately captures the role of the substructure boundary sliding on the deformation of the martensite aggregate. [more]

An atoms eye view of Solar System Evolution

An atoms eye view of Solar System Evolution
  • Date: Sep 15, 2023
  • Time: 10:00 AM - 11:00 AM (Local Time Germany)
  • Speaker: Dr. Luke Daly, University of Glasgow, Scotland, UK
  • Dr Luke Daly is a Reader in Planetary Geoscience at the University of Glasgow. He completed his MSc degree in Geology at Imperial College London. His PhD was with Prof. Phil Bland at Curtin University Australia which focused on platinum group element alloys in meteorites. His current research focusses on applying correlative microscopy including atom probe tomography to meteorites and asteroid sample return mission materials in order to understand how our Solar System formed and evolved: in particular, trying to answer the question of how Earth became a habitable planet. He is a participating scientist on JAXA's Hayabusa 2 mission and treasurer of the UK Fireball Alliance - a network of meteor cameras that successfully recovered the Winchcombe meteorite in 2021.
  • Location: MPIE, virtual seminar
  • Host: Dr. Patricia Jovičević-Klug
  • Contact: p.jovicevic-klug@mpie.de
Atom probe tomography is a powerful technique that has a long history in Material Science applications, however, it has only recently been applied to geological and extraterrestrial materials. In this talk I will present the work we have been conducting using atom probe tomography to date some of the oldest minerals in the Solar System and determine how space weathering could provide a new reservoir of water on the Surfaces of airless worlds. [more]

Effect of droplets on inhibitor performance for steel and galvanized steel

Effect of droplets on inhibitor performance for steel and galvanized steel

Real-time hydrogen visualization system with high spatial and temporal resolutions: Imaging the preferential hydrogen permeation at grain boundaries of pure Ni

Real-time hydrogen visualization system with high spatial and temporal resolutions: Imaging the preferential hydrogen permeation at grain boundaries of pure Ni

Stability of electrochemical hydrogen charging into iron in an aqueous solution containing NH₄SCN

Stability of electrochemical hydrogen charging into iron in an aqueous solution containing NH₄SCN
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