Graduate School of Engineering
Department of Materials Science

Nano-materials Science
High Temperature Materials (Prof. Yoshimi)

Research Topics

Our research group has maintained its history and tradition of excellence by addressing high-temperature structural materials that can be a solution to the global environment and energy resource problems. The major interests of the group are design and life-time evaluation of novel high temperature structural materials that include refractory-metal based superalloys, heat-resistant steel, intermetallics based composites and heat-resistant ceramics through mechanical property characterization at ultrahigh temperature and advanced microstructure analysis.

(1) Development of Novel Ultra-high Temperature Materials Based on MoSiBTiC Alloys

The thermal efficiency of heat engines, such as turbines engines for aircrafts and electric power generation, is enhanced by increased operation temperature. The MoSiBTiC alloy, a novel ultrahigh temperature material developed by our group, exhibits outstanding strength at elevated temperature compared with Ni based superalloys that are commonly used in hot sections of heat engines and moderate damage tolerance at ambient temperature. The goal is to establish the alloy design strategy to attain satisfactory materials performance in terms of fracture toughness, creep strength, and oxidation resistance.

Fig. 1

3D SEM Microstructure of 1st Generation MoSiBTiC alloy. Copyright: Kyosuke Yoshimi

(2) Design of Advanced Heat-Resistant Steels.

Increased efficiency of thermal power plants leads to reduced CO2 emission and fossil fuel consumption. For example, the Advanced Ultra Super-Critical (A-USC) power plant, which is a steam power plant with the steam temperature higher than 700℃, is being realized in near future, however the conventional ferritic heat resistant steels cannot withstand such high temperature circumstances. We aim to develop novel heat resistant steels superior to conventional 9-12Cr ferritic steels from a new perspective of alloy design.

Fig. 2

3D reconstruction of the precipitates formed in a crept heat-resistant steel. (blue: M23C6, yellow: Laves phase)

(3) Intermetallic and Ceramic Based Compounds for Aviation and Transportation Applications.

Intermetallic/ceramic composites have great potential for aviation and transportation applications, since they are strong, light-weight and heat-resistant. We study the physical, chemical, and mechanical properties of various classes of intermetallic and ceramic based materials to identify the effective material design guidelines.

Fig. 3

Atomic-scale ordering parameter in Fe-40mol%Al intermetallic compound. Copyright: Kyosuke Yoshimi