Simulation of the mechanical properties of an aluminum matrix composite using X-ray microtomography
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I. INTRODUCTION
TWO-phase systems consisting of discrete entities embedded within a continuous matrix are an important class of material in a number of fields within materials science and engineering. In many cases, the second phase is a deliberate microstructural feature, designed to improve material performance, for example, (1) ceramic reinforcement particles/fibers in a composite material can increase stiffness, (2) a fine dispersion of precipitates in a heat-treatable alloy can improve strength, and (3) a porous network in a polymer material can improve insulation properties. In other cases, the second phase may be an undesirable defect, for example, a pore in a casting, a coarse intermetallic, an inclusion, or a crack. Whether the second phase is a deliberate inclusion or an accidental contamination, understanding the effects of the shape, size, and distribution of second-phase entities on bulk mechanical properties is a challenging task for current simulation techniques. Figure 1 shows some of the common defects found in one class of two-phase materials, particulate-reinforced metal matrix composites (PMMCs). PMMCs have received considerable attention for use in various engineering applications due to their potentially enhanced mechanical properties compared to monolithic alloys. The degree of property enhancement depends on morphological factors such as volume fraction, size, shape, and spatial distribution of the reinforcement phase, as well as the constituent material properties, load-transfer mechanics, and associated stress/strain profiles and residual stress states arising from heat treatment or prior work hardening.[1,2] It is worth noting that rapid, accurate, and nondestructive characterization of three-dimensional (3-D) microstructural I.G. WATSON, Doctoral Student, P.D. LEE, Professor, and R.J. DASHWOOD, Senior Lecturer, are with the Department of Materials, Imperial College London, London, SW7 2BP, United Kingdom. Contact e-mail: [email protected] P. YOUNG, Senior Lecturer, is with Simpleware Ltd., Innovation Centre, University of Exeter, Exeter, EX4 4RN, United Kingdom. This article is based on a presentation made in the symposium “Computational Aspects of Mechanical Properties of Materials,” which occurred at the 2005 TMS Annual Meeting, February 13–17, 2005, in San Francisco, CA, under the auspices of the MPMD–Computational Materials Science & Engineering (Jt. ASM-MSCTS) Committee. METALLURGICAL AND MATERIALS TRANSACTIONS A
features is a goal in many areas of materials science, not just composite design. For example, the pore size, shape, and interconnectivity of bioactive glass foams (for tissue scaffold applications[3]) must be carefully controlled to encourage nutrient flow and vascularization while maintaining sufficient mechanical strength and stiffness.[3] Other cellular materials have useful mechanical, thermal, and acoustic properties and are frequently used in fields such as packaging, lightweight sandwich panels, and crashworthiness.[4] In monolithic alloys, the presence of un
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