Room temperature mechanical properties and tensile creep behavior of powder metallurgy processed and hot rolled Al and Al–SiCp composites

Room temperature mechanical properties and tensile creep behavior of powder metallurgy processed and hot rolled Al and its composites with 5, 10, 15 and 20 vol.% SiC particulate reinforcements, have been evaluated. The cracks introduced in particles or at particle–matrix interfaces of the composites by hot rolling are found to increase with SiC volume fraction, and adversely affect mechanical properties. Although dynamic Young's modulus, matrix microhardness, yield and ultimate tensile strengths increase moderately with SiC content, yet the differences between moduli obtained experimentally and from rule of mixtures increase due to poor interfacial load transfer. Creep curves obtained at 21 MPa and 623 K show primary, secondary and tertiary regimes, with steady state creep rate increasing and time to rupture decreasing with increasing SiC volume fraction following Monkman–Grant relationship. Studies of tensile and creep fracture surfaces have revealed matrix and particle–matrix interfacial damage, respectively as having dominant role in failure.

Research highlights▶ Flaws introduced during rolling of Al-SiCp composites increase with particulate volume fraction. ▶ The interface cracks are more detrimental for creep than for room temperature mechanical properties. ▶ Young's modulus, microhardness, yield and tensile strength increase modestly with rising SiCp content. Because of poor load transfer. ▶ Creep resistance is found to decrease with increasing SiCp content, because of poor load transfer. ▶ The creep life of Al-SiCp can be predicted from steady state creep rate by Monkman-Grant relationship.