KINETICS OF RELAXATION OF DISORDERED GRAIN-BOUNDARY DISLOCATION ARRAYS IN ULTRAFINE GRAINED MATERIALS

In our recent work (1) disordered arrays of extrinsic grain boundary d islocations (EGBDs) have been suggested to be a part of nonequilibrium grain boundary structure formed during preparation of ultrafine grain ed (UFG) materials by severe plastic deformation. In the present paper the relaxation kinetics of such arrays is studied by computer simulat ion in order to check if they are stable at room temperature. The rela xation law exp(-t(1/2)) obtained by simulations is similar to the kine tics of recovery of volume expansion in UFG nickel at moderate tempera tures studied by a dilatometric method (2) that gives a support to the role of disordered EGBD networks in the properties of UFG materials.