The malleability of gold

Abstract

Alone among the metals, gold can be rolled and beaten to a thinness less than the wave-length of visible light, but so far there has been no scientific explanation of this unique property. In this paper the authors show that gold can accommodate plastic deformation even when the thickness is less than the size of the sub-grains formed, whereas with other metals fragmentation occurs when the foil thickness reaches the sub-grain diameter. This unusual behaviour of gold is attributed to the absence of an oxide film, which enables dislocations to escape from the surface of the metal.