Emission processes accompanying deformation and fracture of metals

Present-day physical methods of investigation reveal that the fracture and plastic deformation of metals is accompanied by emission processes, in part icular, by luminescence and emission of electrons. All the metals studied t hus far exhibit a capability of luminescence. The intensity, duration, and spectrum of mechanoluminescence are different for different metals. The int ensity is determined by the mechanical and thermal characteristics. For a g iven metal, the intensity depends on dislocation density in the structure a nd the sample loading rate. The spectrum of noble metals is governed by the electronic structure of surface states. The dynamics of mechanoluminescenc e and electron emission (exoemission) depends on the rate of stress variati on in the sample under study. This permits one to consider the mechanolumin escence and exoemission not only as physical characteristics but also as a potential tool for probing surface states in metals and the kinetics of eme rgence of mobile dislocations on the surface with a high time resolution. ( C) 1999 American Institute of Physics. [S1063-7834(99)02005-5].