Characteristic emission of negatively charged particles during tensile deformation of oxide-covered aluminum alloys

Abstract Electrons, positive and negative ions as well as photons are known to be emitted from oxide- covered pure polycrystalline Al, Ni, and Ti during tensile deformation. It has been shown that the propagation of cracks in the oxide is uniquely associated with this so-called tribo-stimulated exoemission phenomenon. In this paper we report recent results of tribo-stimulated emission of negatively charged particles from bare and Al-clad aluminum alloys. The investigated samples were anodically oxidized under various conditions such as to produce oxide layers of different thickness as well as chemical and mechanical properties. Of particular interest in this connection are certain porous oxides which facilitate adhesive bonding. The characteristic exoemission curve (emission rate versus strain of the Al substrate) is obtained by measuring the number of emitted negative particles as a function of strain ϵ during tensile deformation of the sample with a constant strain rate dϵ/dt. The features of the curves obtained from different oxides are compared. Initial evidence is presented indicating that the exoemission curve is unique for a given oxide- metal alloy system and has potential as a monitor of certain characteristics of the oxide layer.