Faculty and Staff
- Ryosuke Kainuma
Phase diagram is sometimes referred as "Map for development of advanced materials". One of our missions is to experimentally determine phase diagrams in various alloy or compound systems and to thermodynamically analyze the Gibbs free energy of phases in their systems.We are also assessing diffusivity and mobility.
Microstructural control is one of our research topics. We are investigating texture, grain growth and precipitation in structural and functional materials. These researches are closely related not only to fundamental understanding of microstructures but also to development of new materials. We have succeeded in obtaining superelasticity in Fe-based alloy by the combination of the above-mentioned microstructural controls.
NiTi (Nitinol) alloys which are of the most famous shape memory (SM) alloy system have been already applied in several industrial and medical fields. The low ductility and the non-magnetism of Nitinol, however, restrict to expand the practical field. Recently, we have developed a new kind of SM alloys Cu-Al-Mn with high ductility and SM properties. This new material has been practically applied to a medical device for correcting ingrown nails. Recently, we have been developing a large-scale Cu- and Fe-based SM alloys for buildings, in which the abnormal grain growth for single crystal is one of the key issues. Ferromagnetic SM alloys are also one of our research targets. Up to now, we have found a lot of new alloy systems including the Ni-Mn-based and Co-based Heusler alloys.
HAADF-STEM image of nano-precipitate (NiAl) and stable superelasticity at various temperatures in Fe-Mn-Al-Ni alloy.