Wikipedia
A light metal is any metal of relatively low density. More specific definitions have been proposed; none have obtained widespread acceptance. Magnesium, aluminium and titanium are light metals of significant commercial importance. Their densities of 1.7, 2.7 and 4.5 g/cm range from 19 to 56% of the densities of the older structural metals, iron (7.9) and copper (8.9).
Usage examples of "light metal".
Waldo had mounted it on the edge of a light metal hoop which spun with a speed just sufficient to produce a centrifugal force of one g.
Of course, magnesium, another light metal, is going to keep the aluminum company.
Made of light metal, it was an egg-shaped chamber with pantograph arms and legs that had almost human abilities.
The door was hollow, filled with a perforated honeycomb of light metal under the quarter-inch covering of stainless steel.
He could see nothing at first, given the Kite's limited field of view-one disadvantage of using a telescopic sight instead of wide-angle binoculars-but a quick pan picked up the image of a light metal frame containing a sitting figure with legs outstretched as if driving a go-cart.
Properly braced he could punch his way through heavy wood or light metal.
Kawashita was in her cabin, exercising with four light metal poles he’.