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Summary
The compelling need for lightweight, energy-efficient, environmentally benign engineering systems is driving the development of a wide range of structural and functional materials for energy generation, energy storage, propulsion, and transportation. These challenges motivate wider spread use of magnesium—the eighth most common element in the earth's crust and also extractable from seawater. In addition, the ease of recycling, compared with polymers, makes magnesium alloys environmentally attractive. Importantly, with a density of 1.74 g/cm3—about 30% less than aluminum, one-quarter that of steel, and nearly the same as many polymers—magnesium is attractive for lightweight structural systems and, most notably, automotive systems. A typical car weighing 1525 kg currently contains about 975 kg of steel, 127 kg of Al, 114 kg of polymeric materials, and 5 to 6 kg of magnesium (1). It is estimated that 22.5 kg of mass reduction would improve fuel efficiency by around 1%; thus, automotive manufacturers worldwide have goals to increase the Mg content of automobiles to between 45 and 160 kg (1, 2).
