Overview

For the demand of energy saving, our laboratory is developing heat-resistant alloys that can be used even at 1500 ° C or higher, and light alloys that are lighter in density than iron and have high specific strength.

Based on "experimental" works and "theoretical" understanding, including computational material science, to establish the relationships among alloy composition, microstructure and physical properties (nano-micro-meso), we pursue alloy development in the shortest route. We aim to combine microstructure design and composition design for realizing high-level physical characteristics and functions by optimizing the physical properties of each macro hierarchical structure and harmonizing between the layers.

Themes of Our Researches

1. Microstructure and composition design of refractory metal-based super heat-resistant alloy
   

   "Refractory metals" such as Nb, Mo and Ta show superior strength at high temperature range above the melting point of conventional alloys based on iron and nickel. In order to realize high-efficiency power generation based on gas combustion including H₂ and NH₃ at high temperature, we aim to further improve their characteristics by combining an oxidation-resistant coating and a composite reinforced phase.

2. Development of high-strength super light weight materials
   

   For the improvement of the deformability and strength of Al and Mg alloys, effect of additives such as rare-earth elements, and a new strengthening phase such as LPSO, have been investigated based on mainly experimental studies on plastic deformation of single- or bi-crystals, and on ternary or higher order phase diagrams. By controlling nanoclusters and precipitates, we will create Al-based alloy with an excellent strength-ductility balance.

3. Basic research on a relationship between various properties and microstructure of crystalline materials
   

   It is well known that the properties of crystalline materials are strongly influenced by lattice defects such as dislocations and grain boundaries, solute atoms, precipitates, and other secondary phases. The purpose of this study is to obtain basic knowledge on the relationship between mechanical properties and microstructure of various crystalline materials, such as aluminum alloys, copper alloys and carbide ceramics, using nano indenter and uniaxial tensile / compression testing machine and various electron microscopy. Based on the knowledge obtained, we will establish a material design guideline with superior properties.

4. Theoretical calculateion and computer simulation
   

   For understanding behavior of materials from the atomistic points of view, we also use techniques of the computational material science. The electronic structure calculation is used for obtaining from the first-principles the energy of solids which is the key to understand the phase stability of the materials. For treating stochastic and temperature depending aspect of materials, we use Monte Carlo simulation based on Metropolis algorithm or kinetic Monte Carlo. We also adopt the molecular dynamics method and the phase field simulation for bridging the atomic-scale world where the interactions between the individual atoms decide the motion of players and the larger-scaled world where dislocations and phase boundaries play important roles.