By J. M. Amado, J. N. Montero, M. J. Tobar, A. Yañez

Functionally graded materials (FGM´s) are usually described as composite materials in which composition and structure varies gradually from one point to another. Traditional composites are based on homogeneous mixtures where the properties of the respective components are averaged according to their relative proportion. Therefore a compromise must be made between the desired properties of each constituent. In contrast, the need for a compromise is eliminated in FGM: the graded design ensures that the full performance of each component is obtained at some point of the composite material.

A wide range of processing methods is available today for the fabrication of graded structures with almost any material combination. Most of them rely on well established processing routes as powder metallurgy or melt processing. Direct metal deposition (laser cladding), for example, can be adopted for the production of FGM by feeding with mixed alloy powders with controlled compositions. This can be achieved by using pre-blended powders at desired mixing ratios or, even better, by using separately controlled powder hoppers. In this last case, mixing ratios can be changed online during processing. Continue reading →