The spectrum of rate controlling deformation mechanisms operating in creepin an Al-8.5Fe-1.3V-1.7Si-15SiC(p) composite at temperatures ranging from 623 to 948 K

Creep in an Al-8.5Fe-1.3V-1.7Si alloy reinforced with silicon carbide parti culates-an Al-8.5Fe-1.3V-1.7Si-15SiC(p) composite-is investigated at temper atures ranging from 623 to 948 K. At temperatures 623, 673 and 723 K the cr eep is associated with a true threshold stress decreasing with increasing t emperature more strongly than the shear modulus of the composite matrix. Th e true activation energy of creep is close to the activation enthalpy of la ttice diffusion in the composite matrix and the true stress exponent of min imum creep strain rate is close to 5. The creep is interpreted in terms of athermal detachment of dislocations from incoherent Al-12(Fe,V)(3)Si phase particles in the matrix. At temperatures 773, 798 and 823 K the true threshold stress is not observe d. The true stress exponent of minimum creep strain rate increases with inc reasing stress and the true activation energy of creep is higher than the a ctivation enthalpy of lattice diffusion in the matrix. The creep is interpr eted in terms of thermally activated detachment of dislocations from the in coherent Al-12(Fe,V)(3)Si phase particles. At temperatures ranging from 873 to 948 K the true threshold stress reappea rs. However, its origin is different from that at temperatures 623-723 K. T he true activation energy is close to the activation enthalpy of grain boun dary diffusion and the true stress exponent of minimum creep strain rate is close to 2.5. The creep at these temperatures is interpreted in terms of s uperplastic flow.