Creep behavior of DS aluminum reinforced by silicon carbide particulates-DS AL-10SiCP Composites

摘要

Creep deformatio and fracture behavior of SiC paticulate-reinforced AL-C-O composites ahs been investigated in the temperature range of 623 to 723K. The results show that the creep behavior of the composites is characterized by high values for both the apparent stress exponent and the apparent activation energy, but the stress and temperature dependence of creep rattes fo the composites is similar to those of AL-C-O aloys. However, the addition of SIC particulates in AL-C-O alloy decreases creep rates by 2-4 orders fo magnitude, compared with the matrix alloys, This abnomal creep behavior can be rationalized suing a substructure-invariant model with a stress exponent of 8 and an activation energy close to that for the lattice self-diffusion of aluminum together iwht a threshold stress. The threshold stress completerly refiects the effects of the disperse particies on creep rsistance. But partly refiects the contribution of SIC paritculated. THe creep strenethening effect of SIC particulastes may be attributed to a loas transfer mechanism. Finally, the power dependence of rupture time on stress is shown to be consiten with a desciption of creep fracture based on diffiusive cavity growth continuous nucleation.