Magnesium: Super Material of the Future

Cars could use more magnesium alloys to save on both weight and fuel, but only if engineers can figure out how to make one of the most widely available metallic elements on Earth capable of withstanding industrial manufacturing processes.

Magnesium burns at high temperatures with a brilliant white light, which has made it popular for use in fireworks and school science lab experiments. Now an urgent need for more lightweight, energy-efficient and environmentally friendly materials could turn magnesium into a revolutionary material for everything from cars and mobile electronics, according to an article published in the May 21 issue of the journal Science.

If certain problems associated with the metal can be overcome, magnesium's light weight and unique properties could make it ideal for use in everything from cars to batteries.

"These challenges motivate wider spread use of magnesium — the eighth most common element in the earth’s crust and also extractable from seawater," writes author Tresa Pollock, a materials engineer at the University of California Santa Barbara.

Wonder material for the future

Manufacturers like magnesium as a possible lightweight material because it has a density that's 30 percent less than aluminum, one-quarter that of steel, and about the same as many plastics.

Ease of recycling also makes it a more environmentally friendly alternative to similarly light-weight plastics derived from petroleum.

Car manufacturers already plan to boost magnesium content in automobiles to between 99 and 353 pounds (45-160 kg), up from just 11 to 13 pounds in the typical car today. Estimates have suggested that reducing weight by almost 50 pounds (22.5 kg) would boost vehicle fuel efficiency by around 1 percent.

That 1 percent reduction in gas consumption by vehicles nationwide could save 100,000 barrels of oil per day, according to the Natural Resources Defense Council.

Magnesium looks similarly promising for use in rechargeable batteries, including all-liquid batteries that could help store solar energy. The metallic element's good electromagnetic and radio frequency shielding properties also makes it attractive for use in cell phones, computer cases, cameras and more.

Still, magnesium represents the most complex candidate of the widely available metallic elements used in engineering materials. Scientists and engineers must first better understand its mechanical, chemical and physical nature, Pollock said in her article.

How to make it work

One of the biggest limitations of magnesium comes from its fairly inflexible hexagonal structure, at the most basic atomic level — a limitation that makes it trickier for manufacturers to roll, extrude or stretch the metal into whatever shapes they need.

A possible solution comes from creating metal alloys that include magnesium and other elements, in order to find the right mix with the right properties. Certain rare earth elements such as yttrium, lanthanum, cerium, and neodymium can reinforce the structure and properties of magnesium alloys, but also add to the cost because of supply issues.

Researchers also recently created a new low-cost alloy based on aluminum, calcium and magnesium, which may prove useful for lightweight, high-temperature components in automotive powertrains.

Perhaps the most promising future alloys have yet to be discovered. New computer models allow scientists and engineers to predict and even test the strengths and weaknesses of new alloys, which can speed up the rate of material design and innovation.

"The availability of high-fidelity modeling tools permits a greater compositional space to be explored, increasing the likelihood that new, optimal solutions are identified," Pollock noted.

Jeremy Hsu
Jeremy has written for publications such as Popular Science, Scientific American Mind and Reader's Digest Asia. He obtained his masters degree in science journalism from New York University, and completed his undergraduate education in the history and sociology of science at the University of Pennsylvania.