Creep behaviour of aluminium strengthened by fine aluminium carbide particles and reinforced by silicon carbide particulates -: DS Al-SiC/Al4C3 composites (vol A268, pg 236, 1999)

Creep behaviour of aluminium strengthened by fine aluminium carbide particles and reinforced by silicon carbide particulates is investigated. For comparison, the results for two dispersion strengthened (DS) A1C alloys denoted DS A1C1 and DS A1C2 are presented. (C1 and C2 mean the contents of carbon in wt% which define the volume fractions of Al4C3 particles in DS A1C alloys as well as in SiC/A1C composite matrices). The volume fraction of SIC particulates in composites, denoted SiC/A1C1, SiC/A1C2 and SiC/A1C3, was fixed to 10 vol.%. The creep in both DS A1C alloys as well as in SiC/A1C composites is associated with relatively high true threshold stress sigma(TH). The linear regression analysis showed that the true stress exponent of minimum creep strain rate of 8 should be preferred to that of 5. The creep strain rate was found to be controlled by lattice diffusion in the matrix metal-aluminium. The creep strength of the SiC/A1C composites increasing with the volume fraction of Al4C3 particles is entirely due to the effect of this fraction on the threshold stress. This is not the case of DS A1C alloys. The difference of the creep strength in SiC/A1C composites and the respective DS A1C alloys could be accounted for by the load transfer effect. The athermal detachment of dislocations from fine Al4C3 (and Al2O3) particles dispersed in the composite matrix is considered as the creep strain rate controlling process. (C) 2000 Elsevier Science S.A. All rights reserved.