Microstructures and mechanical properties of bulk nanocrystalline Fe3Al materials with 5,10 and 15 wt. Cr prepared by aluminothermic reaction

摘要

Bulk nanocrystalline Fe3Al based materials with 5, 10 and 15 wt. % Cr were prepared by aluminothermic reaction, in which melts were superheated about 1500 K before solidification. Microstructures of the materials were investigated by optical microscope, electron probe microscope, X-ray diffraction and transmission electron microscope. It shows microstructure of the materials consist of nanocrystalline matrix phase, which were composed of Fe, Al and Cr elements and a little contamination. The nanocrystalline phase was disordered bcc structure, microstructure did not change with content of Cr. Average grain sizes of the nanocrystalline phase of the materials with 5, 10 and 15 wt. % Cr were 33, 21 and 37 nm, respectively. Compressive properties and hardness of the materials were tested. It indicates the materials had a large plastic deformation and did not fracture in compression. Yield strength of the materials was about three times higher but hardness was a little lower than those of Fe3Al material with coarsen grain. The hardness and yield strength varied slightly with content of Cr and that of the material with 10 wt. % Cr was a little lower. Average grain sizes of the materials plunged after the compression.