Ultrahigh-flux concerting materials unit
Organized Session: Nov. 9th, 9:00am - 12:00am (JST)Materials for fusion and other nuclear reactors, aerospace crafts, chemical plants etc. areused under extreme conditions of localized stress and steep gradient of temperature andcomposition. In addition, radiation damage is also overlapping under neutron and otherirradiation conditions, leading to ultrahigh flux of energy and various particles in materials.
Such non-equilibrium conditions induce amorphous and metastable compounds (metastablephase), and self-organization of constituent atoms including crystal lattice defects. As thehydrodynamic vortex in fluid and skin color patterns of animals, such as giraffe and zebra,
metastable cyclic pattern structures are produced in mesoscale larger than the water moleculeand plasmas in the former case, and biological cell and coloring agent in the latter case.
Self-organization patterns with an interval of several 10 nanometers to microns have been
identified many times even in solid matters with strong atomic bonding for hard enoughself-standing crystal, under heavy-cycle deformation, and neutron and ion irradiation
conditions.
Even though formation of the metastable phase and mesoscale patterns has been
analyzed and well simulated by experiments and calculations, their physics are still incomplete,
novel and very interesting to reveal how the self-organization phase and patterns induce themacroscopic properties. Based on the physics, the non-equilibrium self-organization structure
can be correlated with the material properties, and enables us for materials design to accelerate
the adaptive structures to the extreme conditions. One of the purposes of this research unit is aparadigm shift from resistant and stable materials to adaptive and metastable materials, leading
to 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 basedon the understanding of reversibility and irreversibility of materials structure and properties,
and seeks long life materials and precision estimation of their life to develop engineeringsystems using the minimum materials for compatibility with economical and safetyrequirements.
This research unit investigates structural and functional materials. The structural
materials for investigations consist of metals and ceramics, however their boundary is notnecessarily clear. The metallic materials investigated are (1) refractory metals, where covalentbond is relatively larger than the other metals, and therefore good high-temperature strength isexpected as ceramics, and (2) non-refractory metals strengthened by dispersion of refractory
ceramic nano-particles. On the other hand, ceramic materials investigated are to be modified formetallic pseudo-ductility etc. by extrafine fibrillization, joining and composite assembly withmetallic materials. Besides, the ceramic functional materials are to be improved by metallic
dispersion and introduction of supersaturated non-metallic ion vacancy defects andaccompanied metallic bonding, in order for novel and accelerated functional characteristics. In
other words, meta-states, such as ceramic metals and metallic ceramics, are expected to create
novel materials. The fabrication for the meta-state materials is generally composed of
microstructural control by non-equilibrium hybrid processes. From a viewpoint of condensed
matter physics, control of collective atoms dynamics including crystal lattice defects inmaterials is indivisible and continuum through the engineering stages for the production anduse of materials, thus the research unit seeks their comprehensive understanding andsystematization.

In the functional hydrogen materials field, investigations and discussion formechanisms and applications of ultrahigh flux of hydrogen atoms much greater thanequilibrium, using injection of accelerated hydrogen ions into high hydrogen solubility
materials with a less solubility coating on the injection surface, are ongoing. Challenging goals
are, for examples of various applications, (1) creation of extremely greater hydrogen storage
than intrinsic solubility limit in materials, using the supersaturated-hydrogen-induced
metastable phase as the trapping site, and (2) high efficiency tritium decontamination by
isotope exchange under high-flux hydrogen in the clearance of expecting materials after the use
in nuclear reactors.