CREEP OF SILVER AT 900 DEGREES-C

Creep behaviour of polycrystalline silver at 900 degrees C depends pri marily on the purity of the Ag. Specimens of 99.999% purity dynamicall y recrystallized during creep; the stress for recrystallization was ap proximate to 3.5 MPa. Oxygen partial pressure had no effect on the cre ep response. For 99.9% Ag, no dynamic recrystallization occurred; inst ead, steady-state creep was observed, with the rate-controlling deform ation occurring primarily by dislocation motion. Long-term annealing o f 99.9% Ag in O-2 increased the steady-state stress by a factor of app roximate to 5. Depending on test conditions, the 99.9% Ag was up to tw ice as strong as the 99.999% Ag.