Processing and characterization of graded metal/intermetallic materials: The example of Fe/FeAl intermetallics

In this work, a novel processing routine for the fabrication of graded metal/intermetallic materials is shown. It is a combined process that begins with “layer by layer” manufacturing of the 3-D components from the elemental metal powders under computer-aided design and manufacturing (CAD/CAM), followed by low-temperature uniaxial pressing under cycle loading and subsequent sintering at high temperature. The ability to fabricate heterogeneous metal-intermetallic materials with a continuous and/or discrete intermetallic gradient was demonstrated by producing graded Fe/FeAl materials as an example. The microstructure of the graded Fe/FeAl materials was investigated with X-ray diffractometer (XRD) and scanning electron microscope (SEM) coupled with a backscattered electron detector (BSE) and an energy dispersive spectrometer (EDS). In both of the investigated materials, Fe and FeAl intermetallic compounds with different amounts of Al and aluminum oxides were found. The mechanical properties of the graded Fe/FeAl materials were examined with a static compression test. The Fe/FeAl material with a continuous gradient exhibited higher compression strength than the material with a discrete gradient.