Threshold creep behaviour of an Al-8.5Fe-1.3V-1.7Si alloy reinforced with silicon carbide particulates

Creep behaviour of an Al-8.5Fe-1.3V-1.7Si (8009Al type) alloy reinforced wi th 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 62 3-723 K the creep is associated with a true threshold stress decreasing wit h increasing temperature more strongly than the shear modulus. The minimum creep strain rate is controlled by the lattice diffusion in the composite m atrix and the true stress exponent is close to 5. At temperatures 748-823 K the true threshold stress is not observed, the tr ue activation energy of creep is higher than the activation enthalpy of lat tice diffusion in the composite matrix and the true stress exponent of mini mum creep strain rate increases with increasing applied stress. The creep b ehaviour at these temperatures is interpreted in terms of thermally activat ed detachment of dislocations from fine incoherent particles.