Ultrahigh-flux Concerting Materials Unit

Research Summary

What are ultrahigh-flux concerting materials

The word ultrahigh-flux means the state of flow of tremendous energy and matters. The materials used in fusion and fission reactors, aerospace crafts and chemical plants, are exposed to huge heat flow and intense particles beam. The subject of the research unit is creation of self-fitting materials not only damaged under such severe conditions, but transform their own structures to adapt to the ultrahigh flux, as music harmony for concerting.

image
Figure1. Materials concerting with ultrahigh flux.

Focus of the subject in the research unit

Materials for fusion and other nuclear reactors, aerospace crafts, chemical plants etc. are used under multiplex extreme conditions, where non-equilibrium states are promoted with ultrahigh-flux energy and various particle matters by steep gradient of temperature, stress and compositions, in some cases overlapped with radiation damage due to neutron and other particles irradiation. Such non-equilibrium conditions induce amorphous and metastable compounds (metastable phase), and metastable periodic patterns (dissipative structure) by self-organization of constituent atoms including crystal lattice defects. New material behavior of so-called adaptation, such as a stop of the deterioration with self-stabilization and even an improvement of the properties, is expected based on profound understanding and utilization of the formation mechanisms for the metastable structures and their contributions to material properties. Especially for the correlation between the inhomogeneous and various mesoscale structures induced by the self-organization, and the macroscopic material properties, such as material strength, its physics is still incomplete, remains to be very interesting and lively subject of studies. Based on the understanding of the mesoscale structure-macroscale property correlation, stable strengthening and functioning agents are introduced and enhanced, leading to a paradigm shift from resistant materials to adaptive materials under the extreme conditions, in order for creation of novel materials. On the other hand, perfect adaptation is absolutely unrealistic, because materials degradation is unavoidable if the adaptive self-organization is less enough for perturbation of the extreme conditions, accumulation and intrinsic mutation of materials damage structure. This research unit focuses on also the unavoidable materials damage based on the understanding and control of reversibility and irreversibility of materials structure and properties, and seeks long life materials and precision estimation of their life to develop engineering systems using the minimum materials for compatibility with economical and safety requirements.

Since fusion environment includes all the multiplex extreme conditions, fusion research can lead the other relating engineering researches. Thus, the research unit investigates and systematizes the physics for adaptation and life of materials, and seeks creation of long-life, high strength and high functioning materials, and establishment of materials theory for life estimation.

image
Figure2. Focuses by the research unit.

Formulation of the subjects and strategy for investigation

Microstructures and dynamics of resulting macroscopic material properties will be understood and controlled based on the collective atoms behavior under the non-equilibrium conditions induced by ultrahigh-flux energy and particle matters. The investigations focus on the stability of the strengthening and functioning agents introduced in the material processing, formation of the metastable phase and development of the self-organization structures. The investigations reveal the effects of temperature, stress and composition fields, and radiation on them, including their synergetic effects, and also establish modellings for understanding of their mechanisms.

In order for material adaptation, the research unit makes profound studies on materials design with strengthening and functioning agents surviving or newly formed under the extreme and non-equilibrium conditions. Based on the fundamental mechanisms for the control of physical life of the agents and microstructures, new material theories will be established for understanding and precision estimation of materials life limited by the macroscopic property degradation under the engineering requirements, and also the systems life composed of various materials and their contact interfaces.

The research targets are categorized into structural materials and functional materials. The structural materials consist of metals and ceramics. The metallic materials for investigations are (1) refractory metals, where covalent bond is relatively larger than the other metals, and therefore good high-temperature strength is expected as ceramics, and (2) non-refractory metals strengthened by dispersion of refractory ceramic nano-particles. On the other hand, ceramic materials for investigations are to be modified for metallic pseudo-ductility etc. by extrafine fibrillization, joining and composite assembly with metallic materials. Besides, the ceramic functional materials are to be improved by metallic dispersion and introduction of supersaturated non-metallic ion vacancy defects and accompanied metallic bonding, in order for novel and accelerated functional characteristics. In other words, meta-states, such as ceramic metals and metallic ceramics, are more promising to create novel materials.

image
Figure3. Meta-states in the classification of solid and crystals.

Keywords

Fusion Science

  • Fusion reactor materials
  • Blanket
  • Diverter
  • Vacuum vessel
  • Low-activation materials
  • Fuel breeding materials
  • Neutron multiplier
  • Hydrogen isotopes
  • Hydrogen permeation
  • High heat flux
  • Heavy irradiation

Interdiscipline

  • Metastable phase
  • Self-organization
  • Mesoscale structure
  • Physical properties
  • New materials creation
  • Strength
  • Hydrogen super-permeation
  • Hydrogen storage
  • Lattice defects
  • Deformation
  • Diffusion
  • Metals
  • Ceramics
  • Composites
  • Coatings
  • Interface
  • Structural materials
  • Functional materials
  • Non-equilibrium thermodynamics
  • Non-equilibrium statistical mechanics
  • Non-equilibrium chemistry
  • Severe environment
  • Lifetime
  • Adaption

Unit Members

NAGASAKA, Takuyaorcid Research Fields Metals, Strength, Fusion reactor structural materials
TANAKA, Teruyaorcid Research Fields Ceramics, Materials science, Fusion reactor systems
TAKAYAMA, Sadatsugu Research Fields Ceramics, Electromagnetics, Microwave applications
KOBAYASHI, Makotoorcid Research Fields Ceramics, Physical chemistry, Hydrogen isotope applications
NOTO, Hiroyukiorcid Research Fields Metals, Metallurgy, Material systems & processing
Shen, Jingjieorcid Research Fields Metals, Histology, High heat flux plasma facing wall

Contact

Ultrahigh-flux concerting materials Unit
Email: ulcomat(at)nifs.ac.jp
*Replace (at) with @.