Determination of fiber length in axially symmetrical metal matrix composites

A procedure to calculate the spatial fiber length in discontinuously reinforced composites from data of conventional metallographical images has been developed. The method is based on the following three assumptions: first, the measured length of a reinforcing fiber in a metallographical picture is a projection of the actual fiber length; second, the alignment of short fibers is axially symmetrical (for example, extruded composites in which the extrusion direction is a symmetry axis for the orientation of reinforcing fibers); third, for a representative number of fibers, the dependence of the projected length with the corresponding projected angle, along a given sample direction, is known. Either analytical or numerical solution can be found depending on the specific dependence of the projected length with the projected angle. This procedure has been applied to real 6061Al–15vol%SiCw composites obtained by a powder metallurgical route in which the final step for materials consolidation was extrusion of powder blends at different temperatures.