| Abstract: | Systematic studies of the mesoscopic mechanisms of deformation of polycrystalline materials of lead and its alloys have been
carried out under conditions of sign-alternating bending at room temperature. It has been shown that fatigue failure is due
to the evolution of vortices of mesoscopic substructures. Multiple slip separated in adjacent grains is the basis for this
kind of deformation. This causes extremely strong localization of the displacement in individual favorably oriented grains
and self-organization of these grains in agreement with regular structural levels of deformation. In polycrystalline lead,
the mesoscopic substructure has a block character, with each block containing several grains. The elements of such substructures
are nucleated in stress mesoconcentrator zones which arise at the grain boundaries under conditions of intense grain boundary
slippage. In the course of cycling they gradually propagate through the whole transverse cross section of the sample, which
completes its failure. Alloying substantially changes the character of the mesoscopic substructures which are formed. We have
considered the different types of vortex mesoscopic substructures and studied their connection with cyclical endurance of
the alloy. Recommendations for increasing the fatigue endurance of plastic polycrystalline materials are given.
Institute of the Physics of hardening and Materials Science, Siberian Section, Russian Academy of Sciences. V. D. Kuznetsov
Siberian Physicotechnical Institute at Tomsk University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.
6, pp. 40–57, June, 1996. |
