Abstract
Creep behaviour of an Al-8.5Fe-1.3V-1.7Si (8009Al type) alloy reinforced with 15 vol. % SiC particulates - Al-8.5Fe-1.3V-1.7Si-15SiC_p composite - is investigated at temperatures ranging from 623 to 823 K. At temperatures 623-723 K the creep is associated with a true threshold stress decreasing with increasing temperature more strongly than the shear modulus. The minimum creep strain rate is controlled by the lattice diffusion in the composite matrix and the true stress exponent is close to 5.
At temperatures 748-823 K the true threshold stress is not observed, the true activation energy of creep is higher than the activation enthalpy of lattice diffusion in the composite matrix and the true stress exponent of minimum creep strain rate increases with increasing applied stress. The creep behaviour at these temperatures is interpreted in terms of thermally activated detachment of dislocations from fine incoherent particles.

Key words
8.5Fe-1.3V-1.7Si-15SiC_p composite, creep, true threshold stress, disappearance of the true threshold creep behaviour

Full text (2685 KB)