Christian Doppler Laboratory "Early Stages of Precipitation"

01.10.2007 - 30.09.2015
Research funding project
Technically relevant structural high-performance materials, such as tool steels, Nickel-base alloys and refractory alloys, owe their superior mechanical properties to specific microstructural features such as small or extremely small grain sizes, the existence of extremely narrow spaced interfaces within grains or a fine dispersion of second phase particles such as precipitates. Hardening by particles is considered as one of the most important strengthening mechanisms. Therefore, improvement of conventional materials and development of new materials require a deep understanding of precipitation reactions and their influence on mechanical properties and thus an extensive characterization is necessary. However, the course of precipitation reactions cannot be followed continuously by any microanalytical technique. The progress of the reaction is usually reconstructed from the microstructure that develops at various stages of the precipitation reaction. Thus, it is necessary to analyse the spatial extension and the amplitude of compositional fluctuations of incipient second-phase particles as well as morphology, number density, size, and chemical composition of individual precipitates at various stages of the reaction. For this purpose microanalytical tools are required that are capable of resolving very small ¿ typically of a few nm ¿ solute clusters and which allow an analysis of their chemical composition. The tools which, in principle, meet these requirements are transmission electron microscopy and atom probe field ion microscopy (direct imaging techniques) as well as small-angle scattering, differential-scanning-calorimetry (indirect imaging techniques). Besides the experimental characterization of precipitation reactions, computer modelling became increasingly important within the last two decades. Nowadays, computer simulations of multi-phase equilibria, i.e. so-called "computational thermodynamics", as well as simulation of phase transformation kinetics are more or less standard tools in materials development and research. However, although many studies can be found in literature aiming at the characterization of precipitates, simulation of the precipitation kinetics as well as the modelling of mechanical properties are still demanded because of limitations and shortcomings of the inspection techniques. Furthermore, the commercially available software packages for the simulation of precipitation kinetics often do not describe the precipitation kinetics in complex metallic materials accurately. Consequently, the proposed Christian Doppler Laboratory is focused on precipitation reactions and the influence of precipitates on mechanical properties of structural high-performance materials. In detail, the following research activities are planned: ¿ Establishing and improvement of inspection techniques (transmission electron microscopy, atom probe field ion microscopy, small-angle neutron and X-ray scattering and differential scanning calorimetry) for characterizing nm-sized precipitates in tool steels, Nickel-base alloys and refractory alloys as well as the improvement of the data evaluation ¿ Detailed characterization of precipitation reactions as well as the development of precipitates during application in high-performance materials by the complementary use of direct and indirect inspection methods ¿ Improvement of the understanding of the relationship between microstructure (precipitates) and mechanical properties ¿ Further development of software tools for the simulation of precipitation kinetics in multi-phase metallic materials

People

Project leader

Project personnel

Institute

Grant funds

  • Christian Doppler Forschungsgesells (National) Christian Doppler Research Association (CDG)

Research focus

  • Special and Engineering Materials: 20%
  • Structure-Property Relationsship: 15%
  • Computational Materials Science: 15%
  • Sustainable Production and Technologies: 5%
  • Modeling and Simulation: 25%
  • Materials Characterization: 20%

Keywords

GermanEnglish
Computer SimulationComputer Simulation
Ausscheidungenprecipitates

External partner

  • Plansee AG
  • voestalpine Stahl Donawitz
  • voestalpine BÖHLER Aerospace GmbH &
  • voestalpine BÖHLER Edelstahl GmbH & Co KG
  • voestalpine Austria Draht
  • voestalpine Stahl Judenburg

Publications