Development of an Approach to Determining the Representative Volume Element of the Al/SiC Metal Matrix Composite Material Fabricated by Squeeze Casting

Abstract

This work is aimed at solving the challenging problem of developing an approach to determining the representative volume of an Al/SiC metal matrix composite material (MMC) with 55 vol % silicon carbide synthesized by a unique squeeze casting technology. This volume is referred to as representative volume element (RVE). Initially, the minimum unit cell size was found by a metallographic method. The RVE of the MMC, where the average filler content is equal to the average filler content in the composite material, begins with a 40 × 40-μm region. The RVE is determined by the finite element method. To perform numerical RVE calculations, we solved the two-dimensional problem of tension an element in the cross section of the MMC consisting of hard SiC particles and a pure aluminum matrix. A stress–strain curve recorded during uniaxial tension is used as the response of MMC to an external action. The problems with regions of 40 × 40, 50 × 50, 70 × 70, 100 × 100, 200 × 200 and 400 × 400 μm are solved. The results of the numerical calculations demonstrate that the minimum RVE of the Al/SiC MMC with 55 vol % silicon carbide is 200 × 200 μm. In addition, depth-sensing indentation is recommended as an experimental method for estimating RVE. When a pyramidal indenter is pressed into the surface of an MMC sample, the indentation diagram reflects the influence of both the composite matrix and silicon carbide particles. The indentation force (correspondingly, surface area) used in experiments is such that the influence of the site of indentation on the indentation diagram is minimal. Instrumented indentation used to determine RVE demonstrates that it is 200 × 200 × 200 μm.