AN INVESTIGATION OF CREEP-BEHAVIOR IN AN SIC-2124 AL COMPOSITE

The creep behavior of powder metallurgy (PM) 10 vol.% silicon carbide particulate reinforced 2124 aluminum (SiCp-2124 Al composite) was stud ied under experimental conditions identical with those used in an earl ier investigation on the unreinforced matrix alloy, PM 2124 Al. The re sults show that the creep behavior of PM 10 vol.% SiCp-2124 Al composi te is similar to that of PM 2124 Al with regard to: (a) the variation in both the apparent stress exponent and the apparent activation energ y for creep with applied stress, (b) the value of the true stress expo nent (It = 4.5), (c) the value of the true activation energy for creep (Q(c) approximate to Q(D)), (d) the interpretation of creep in terms of a threshold stress and (e) the temperature dependence of the thresh old stress. These similarities indicate that deformation in the matrix alloy, 2124 Al, controls the creep of the composite, 10 vol.% SiCp-21 24 Al composite; and that SiC particulates are not directly responsibl e for the threshold stress behavior in the composite. A comparison bet ween the creep rates of the composite and those of the unreinforced ma trix alloy reveals that, for constant temperature, strengthening arisi ng from SiC particulates is eliminated at high strain rates and the cr eep strength of PM 10 vol.% SiCp-2124 Al composite becomes essentially equal to that of the unreinforced matrix alloy, PM 2124 Al. (C) 1997 Acta Metallurgica Inc.