Magnesium alloy to make cars greener

By Kim Tong-hyung
Staff Reporter

A lightweight magnesium alloy has been garnering attention for its potential as material for low-emission, fuel-efficient cars of the future.

Now, a team of Korean researchers are claiming a breakthrough in expanding the use of the alloy in car parts and frames by creating a technique to improve the life and durability of this promising light metal.

Pure magnesium is about one-third lighter than aluminum and two-thirds lighter than steel, and in cars, lighter weight translates into greater fuel efficiency. Automakers are already spending a large amount of effort and money to employ hybrid, fuel cell and other automotive technologies to develop green vehicles, and magnesium alloy parts are considered an important piece of the puzzle.

The involvement of magnesium in car frames and parts would reduce the vehicle's weight by around 10 percent and also make it 6 to 8 percent more fuel efficient, according to Lee Chong-soo, a materials science expert from the Pohang University of Science and Technology (POSTECH).

However, the commercial adoption of magnesium in cars has been slowed due to the lack of knowledge over its fatigue behavior, or predicting how the properties of the metal react to stress and time.

In a study published by the recent edition of peer-review journal, Journal of Materials Research, researchers from POSTECH and the Korea Research Institute of Standards and Science (KRISS) added detail to the knowledge of the "twinning/de-twinning" characteristics of magnesium. This transformation behavior plays key roles in the fatigue deformation of magnesium alloys by changing its mechanism of controlling flow stress and fatigue resistance, the authors said.

Based on this knowledge, the researchers said they developed a technique that in theory would improve the durability of magnesium by about 48 percent, and have applied for patent rights for it.

"The development of greener cars based on magnesium alloy parts will depend on the knowledge of the light metal's fatigue behavior, which will be critical in ensuring the safety of passengers in the new designs. We believe that our study will stimulate the efforts to develop vehicles using magnesium," said Lee.

POSTECH's Park Sung-hyuk and KRISS's Hong Seong-gu and Huh Yong-hak were the other authors of the study.

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