Static and cyclic creep behaviour of 2024/SiCp and its matrix alloy at high temperature

Abstract

The tensile creep and tensile-tensile cyclic creep behaviour of 2024/SiCp composite and its matrix alloy have been investigated and analysed at high temperature. It was found that the creep threshold stress of the composite may not be caused by SiCp alone: the matrix alloy also contributes to the threshold stress. The higher threshold stress of the composite compared with that of the matrix alloy can be explained in terms of load transfer in the composite and the value of threshold stress for the matrix alloy. A direct comparison between the composite and its matrix alloy indicates that only below a critical stress does the composite show a creep resistance higher than that of its matrix alloy. The two materials shown cyclic creep retardation in the tested stress range, cyclic creep showing a higher stress exponent and higher apparent activation energies in comparison with static creep. An analysis based on anelasticity is introduced to explain this result. The relationships between rupture lifetimes and applied stress, creep rate, and unloading amount show that the creep fracture mechanism is dominant in the present test condition.