The microstructure and the chemistry distribution of AlNiCo 9 samples were characterized by the X-ray diffraction, magnetic force microscope, field emission scanning electron microscopy and transmission electron microscope. An interface of a high Al content was formed near the FeCo-rich phases with a size of about 30 nm. S elements mainly combined with Ti to form titanium sulfide bars with the length between 70-150 μm, while S elements was not confirmed in the nanostructured FeCo-rich phase and AlNi-rich phase. Si and Nb preferably existed in the NiAl-rich phase, and a higher content Nb near the Cu precipitate boundary was observed. Moreover, the magnetic domain structure of AlNiCo 9 was also studied.

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The microstructure and intergranular corrosion phenomenon were investigated by means of optical imaging,SEM and EDS. Hardness was conducted and electrochemical corrosion properties were researched in 3.5% Nacl solution by electrochemical tester.The result showed, there was no intergranular corrosion phenomenon when the samples underwent cold rolling and stabilization heat treatment;The intergranular corrosion was obviously when the samples were annealed at 180°C for 90h or 150h;The corrosion potential of TO1 state annealed at 180°C for 90h and TO2 state annealed at 180°C for 150h was lower than cold rolled and stabilization heat treatment samples，they were more susceptible to electrochemical corrosion.

The effect of annealing on the microstructural characterization and magnetic properties of 2J4 alloy has been investigated.The alloys were annealed in argon atmosphere for 0.5h at different temperatures.The results indicated that there were some precipitated phases afer annealing,which can pin domain boundary movement, thus leading to improved magnetic energy product and hysteresis properties due to enhanced coercivity and remanence. Magnetic domain morphology showed that the number of domains increased after heat treatment, the exchange energy between magnetic domains and the energy of magnetocrystalline anisotropy increased with increasing domain number,thus leading to better coercivity. With increasing temperature from 620°C to 680°C, saturation magnetization increased at first, and then decreased under the effect of increase in precipitates and decrease in strain and dislocations. The coercivity,hysteresis loss and ratio of the remanence to saturation magnetization keeped increasing due to increase of tiny and dispersed precipitates. This study can provide theoretically a reliable way for preparing 2J4 magnetic alloys with high performance.