This newly developed material is expected to contribute to the weight reduction of automobiles and the like as a lightweight and highly safe metal material.

The Japan Institute of Materials and Materials (NIMS) recently announced that by adding manganese and refining the crystal grains, it has successfully developed a magnesium alloy that can deform like an accordion at room temperature (see figure). The energy absorption properties of the newly developed material are more than three times that of existing materials, so it is expected to contribute to the weight reduction of automobiles and the like as a lightweight and highly safe metal material.

Comparison of compression test results between existing materials and newly developed deformable magnesium alloys

Magnesium is the lightest among practical metal materials, and thus attracts attention as a lightweight material for automobiles and train carriages. However, at room temperature, even if a large force is applied, magnesium can only undergo small plastic deformation and be destroyed instantly. Therefore, from the viewpoint of safety, there are problems such as being unsuitable as a raw material for parts such as automobiles, and incapable of processing complex shapes.

This time, the NIMS research team developed a magnesium alloy that added a very small amount of manganese and refined the crystal grains to 5 μm or less by extrusion at a temperature of 200°C. Using the developed materials and commercially available magnesium alloy materials, a cylindrical test piece with a height of 8 mm and a diameter of 4 mm and a cylindrical test piece with a thickness of 0.7 mm and an outer diameter of 6 mm were fabricated by machining, and compared the two at room temperature. Variation in compression test.

The commercial material was damaged instantly after the oblique cracking, while the developed material was not damaged quickly, but deformed into an accordion or cup shape. This shows that, even when subjected to force, the developed material can absorb energy like a shock absorber and is less prone to damage. The absorption energy of the developed material for damage is more than three times that of the existing material, which is very excellent. The appearance of these phenomena is due to the concentration of manganese between the crystal grains that have become smaller due to the extrusion process, which promotes the 'grain boundary slip' in which the crystal grains slide against each other.

This achievement can be expected to be used for weight reduction of automobile bodies, car seats, train car seats, bicycle stands, and the like. In addition, it is also expected to reduce the temperature of press working and secondary working to achieve energy saving and reduction of equipment cost.