Solidification Processing of Functionally Graded Metal Matrix Composites

Abstract

Functionally Gradient Materials (FGM) exhibit gradual transitions in the microstructure and/or the composition in a specific direction, the presence of which leads to variation in the functional performance within a part. The presence of gradual transitions in material composition in FGM can reduce or eliminate the deleterious stress concentrations and result in a wide gradation of physical and/or chemical properties within the material. Functionally graded metal–ceramic composites (FGMCC) are also getting the attention of researchers. Among the fabrication routes for FGMs such as chemical vapour deposition, physical vapour deposition, the sol–gel technique, plasma spraying, molten metal infiltration, self-propagating high-temperature synthesis, spray forming, and centrifugal casting, the ones based on solidification route are preferred for FGM because of their economics and capability to make large-size products. The present paper discusses and compares various solidification processing techniques such as centrifugal casting, sequential casting, selective infiltration and laser melting for the fabrication of functionally gradient metals and metallic composites.