Internal stress superplasticity in Al-Be eutectic alloy during triangular temperature profile

Materials containing second phases show superplastic behavior during thermal cycling (internal stress superplasticity). In the present study, this behavior has been investigated by thermal cycling creep tests with a triangular wave having fixed heating and cooling rates, using a Be-particle-dispersed Al matrix alloy. The thermal cycling creep rates were much higher than the isothermal creep rates and proportional to the applied stress at intermediate stresses. It was interpreted by the previous theoretical model of internal stress superplasticity, and the values of the thermal cycling creep rate were about 60% of the theoretical one. The discrepancy was explained by the transition after each temperature reversal until achieving the quasi-steady slate stress distribution during thermal cycling. (C) 1997 Acta Metallurgica Inc.