Research Contents
We are facing a number of clear and urgent issues regarding our environment: global warming, climate change, air pollution, high CO2 emission, etc. We need to significantly enhance the environmental sustainability and energy saving; one key method is by reducing the structural weight of metallic materials in the value-added components for transportation systems in automobiles, railway vehicles, ships, and aerospace. Magnesium has a density of 1/4 that of iron and 2/3 that of aluminum, making it the lightest of all practical metals. However, Mg alloys have several technical short comings such as low strength, low corrosion resistance, and low ignition temperature. We are conducting research to overcome these technical problems of Mg alloy.
Research introduction
Our research is aimed to design and develop a "high-strength, non-corrosive, non-combustible magnesium alloy system." We’ve succeeded in developing two new alloys, a long-period stacking ordered (LPSO) phase type magnesium alloy and a C36 type non-combustible magnesium alloy.
Mg alloys with LPSO phase
The Mg alloys, which have a novel phase constituent called the Long-Period Stacking Ordered structure (LPSO) phase, exhibit excellent strength. The main strengthening mechanism is that the LPSO phase undergoes a novel deformation called kink deformation. This LPSO phase is thermally stable and it exhibits high heat resistance. In addition, it has high ignition temperature because the rare earth element of the alloy forms a continuous protective oxide film, which tends to block oxygen’s diffusion into the alloy interior.
C36 type non-combustible Mg alloys
Another important research material is the development of the noncombustible magnesium alloys with intermetallic compounds having a C36 structure. The alloy exhibit : (1) high strength because the C36 compound is finely dispersed during extrusion deformation, (2) excellent corrosion resistance, (3) very high ignition temperature equal to or higher than the boiling point of pure magnesium(1,091℃) by adding Ca, and (4) excellent thermal conductivity.