Laminated metal composites—High temperature deformation behavior

Abstract

A constitutive model for deformation of a novel laminated metal composite (LMC) which is comprised of 21 alternating layers of Al 5182 alloy and Al 6090/SiC/25p metal matrix composite (MMC) has been proposed. The LMC as well as the constituent or neat structures have been deformed in uniaxial tension within a broad range of strain-rates (i.e. 10 −6 to 10 +1 s −1) and moderate to high homologous temperatures (i.e. 0.85 ≥ 0.95 T m). The stress exponent, n, of the Al 5182 layers increases from 3 to 5 with increasing strain-rate (i.e. >10 −3 s −1). The MMC layer's apparent n value decreases from 7 to 5 with increasing temperature. Furthermore, at low strain-rates (i.e. <10 −3 s −1) an apparent threshold stress dominates the MMC's observed mechanical behavior. The LMC structure exhibits a behavior somewhat closer to the MMC layers. The results of these experiments have lead to a characterization of the neat layer's mechanical behavior and a subsequent semi-empirical constitutive rate equation for both the Al 5182 and Al 6090/SiC/25p. These predictive relations for the neat layers have been coupled with a proposed model, which takes into account the dynamic load sharing between the elastically stiffer and softer layers when loaded axially during isostrain deformation of the LMC. This deformation model has led to the development of a constitutive relationship between flow stress and applied strain-rate for the laminated structure, which has been compared with experimental data.