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 studied under experimental conditions identical with those used in an earlier investigation on the unreinforced matrix alloy, PM 2124 Al. The results show that the creep behavior of PM 10 vol.% SiCp-2124 Al composite is similar to that of PM 2124 Al with regard to: (a) the variation in both the apparent stress exponent and the apparent activation energy for creep with applied stress, (b) the value of the true stress exponent (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 threshold stress. These similarities indicate that deformation in the matrix alloy, 2124 Al, controls the creep of the composite, 10 vol.% SiCp-2124 Al composite; and that SiC particulates are not directly responsible for the threshold stress behavior in the composite. A comparison between the creep rates of the composite and those of the unreinforced matrix alloy reveals that, for constant temperature, strengthening arising from SiC particulates is eliminated at high strain rates and the creep 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.