Microstructure and mechanical properties of a large-dimensional bulk nanocrystalline-based Fe-Al-Cr alloy prepared by an aluminothermic reaction casting and followed annealing at 1000 °c

摘要

A large-dimensional bulk nanocrystalline phase-based Fe-Al-Cr alloy with 10 wt. Cr, which was about 200 mm in diameter and 10 mm in thickness, was prepared by an aluminothermic reaction casting and followed annealing at 1000 °C. Microstructures of the alloy were investigated by optical microscope, electron probe microscope, scanning electron microscope attached with electron backscattered diffraction, X-ray diffraction and transmission electron microscope. The magnetization curves of the alloy were tested by Lake Shore 7410 vibrating sample magnetometer. Compressive properties of the alloy were tested. The results show the alloy was consisted of a Fe-Al-Cr nanocrystalline matrix, Cr_7C_3 phase and contaminants in micrometre. Average grain size of the nanocrystalline matrix was 19 nm. Volume fraction of the Cr_7C_3 phase in the alloy was about 4.5. After annealing, the saturated intensity of magnetization and the specific magnetic susceptibility of the alloy increased slightly from 99 emu/g and 0.083 emu/g Oe to 104 emu/g and 0.113 emu/g Oe, respectively. Compressive strength of the alloy was 1200 MPa and much higher than that of the small-scale nanocrystalline alloy and alloy with grains in micrometre.