Graduate School of Engineering
Department of Metallurgy

Materials Forming and Structural Control
Computational Microstructure Design (Prof. Kainuma)

Research Topics

Thermodynamic Analysis for Materials

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

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.

Development of Smart Materials

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.

Fig. 1:HAADF-STEM image of nano-precipitate (NiAl) and stable superelasticity in various temperatures in Fe-Mn-Al-Ni alloy.

Fig. 1:
HAADF-STEM image of nano-precipitate (NiAl) and stable superelasticity at various temperatures in Fe-Mn-Al-Ni alloy.

Fig. 2: Single crystal of Cu-Al-Mn superelastic alloy bars obtained by abnormal grain growth (AGG) induced by cyclic heat treatment. Inverse pole figure (IPF) map and schematic illustration of AGG are also shown.

Fig. 2:
Single crystal of Cu-Al-Mn superelastic alloy bars obtained by abnormal grain growth (AGG) induced by cyclic heat treatment. Inverse pole figure (IPF) map and schematic illustration of AGG are also shown.