Mechanical behavior of silicon carbide particle reinforced aluminum matrix composites.

摘要

Preferred alignment of reinforcement particles has been observed in extruded particle reinforced metal matrix composites. This preferential alignment of particles influences the mechanical behavior of the composite. In the first part of this study, the effect of anisotropy in the alignment of silicon carbide particles on the tensile and fatigue behavior of extruded 2080 aluminum matrix composites for a range of volume fraction was examined. Microstructure characterization showed a preferred alignment of the reinforcement particles parallel to the extrusion axis, although the degree of alignment decreased with increasing reinforcement volume fraction. Young's modulus and tensile strength parallel to the extrusion axis were higher than perpendicular to the extrusion axis. The relationship between tensile and fatigue behavior of the composites to the degree of anisotropy in alignment of the reinforcement particles is discussed.; Conventionally, in numerical analysis, a unit cell is modeled to simulate the deformation behavior of particle reinforced composites. This approach does not yield accurate results due to the oversimplification of the composite microstructure. Therefore, in the second part of this study numerical analysis was carried out using real microstructure in two- and three-dimensions to accurately predict the composite properties. The particle alignment-induced changes in stress-strain behavior were modeled using two-dimensional microstructure-based finite element method, yielding good agreement with experimental results. A serial sectioning process was used to reconstruct three-dimensional microstructure of the composite. The Young's modulus and overall stress-strain behavior of the composite predicted by the three-dimensional microstructure-based model correlated very well with experimental results. It was found that the three-dimensional microstructure-based model predicted the uniaxial tensile behavior of the composite accurately than the three-dimensional unit cell models.; Particle reinforced aluminum alloys are increasingly becoming materials of choice for replacement of conventional aluminum alloys. The fatigue crack growth behavior of these materials is one of the important properties in most of the applications. To date a complete understanding of the fatigue crack growth mechanisms have not been reached. The main reason for this is the lack of data at load ratios ranging from compressive to tensile fatigue loading. (Abstract shortened by UMI.)