Effect of Ni on Microstructure and Mechanical Properties of Bulk Nanocrystalline Fe-AI Based Alloys Prepared by Aluminothermic Reaction

摘要

Bulk nanocrystalline Fe-Al based alloys with 5, 10 and 15 wt. % Ni were prepared by aluminothermic reaction. The alloys were analyzed by electron probe microanalyzer, X-ray diffraction and transmission electron microscope. Compressive yield strength and hardness of the alloys were tested. The experimental results showed that all of the alloys consisted of Fe-Al-Ni matrix and small amount of Al_2O_3 sphere. The matrix phases of the alloys with 5 and 10 wt. % Ni had disordered a-Fe solid solution, while the matrix phases of the alloys with 15 wt. % Ni had disordered α-Fe solid solution, NiAl phase and Fe_3AlC_x phase. Average grain sizes of the matrix phases of the alloys were about 20 nm. The alloys with 5 wt.% Ni had the best plasticity, but the alloys with 15 wt. % Ni had the highest yield strength and hardness. Yield strength of those alloys is higher than that of coarse-grained Fe_3Al.