3-DIMENSIONAL ANALYSIS OF THE CREEP DUE TO A VISCOUS GRAIN-BOUNDARY PHASE

A three-dimensional analysis of creep due to a viscous grain boundary phase is presented where the amount of creep strain is proportional to the volume fraction f of the viscous phase. The transient response of a periodic array of rectangular grains to uniaxial deformation under conditions of either constant applied stress or constant total strain is found using a lower bound solution. The stress redistribution in pu re bending due to viscoelasticity has been calculated. The short lime and long time behaviour of this redistribution depends on the size of Etf(3)/eta(0) in comparison with unity where E and eta(0) are the Youn g's modulus and the viscosity of the boundary phase. The creep respons e of the periodic array caused by more general stress states is found and this result has been used to estimate the effective viscosity of a n equiaxed polycrystal. The effect of the creep path upon the anisotro py is discussed. Copyright (C) 1997 Acta Metallurgica Inc.