Effect of the Heat Treatment on the Structure and the Properties of the Electrodeposition Fe-Ni-S Amorphous Alloy

The Fe-Ni-S amorphous alloy film was electro-deposited in an acidic bath containing boric acid as a buffer agent, sodium citrate as a complexing agent and saccharin and 2-butyne-1,4-diol as the additives. The crystallization behavior and surface micromorphology of the alloy were studied by differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and scanning electron microscope (SEM). It was found that the structure of the as-plated coating is amorphous. The microcrystalline Fe7Ni3 (Im3m) started to appear in the amorphous alloy coating at 250 . The crystallized phases of NiS (R3m )a nd FeNi 3 (Pm3m) began to produce at 320.4 , and the amount of this kinds of phases increased with increasing in temperature. The crystallization finished at 500 and a large number of the crystal grains had 100-200 nm in diameter. The effect of the heat treatment temperature on the magnetic properties, the micro-hardness and the corrosion resistance of the coating were investigated. As a result, the magnetic properties, micro-hardness and corrosion resistance of the coating rose with the increase of the heat treatment temperature bellow 250 , then, they all decreased with the increase of the heat treatment temperature above 250 . The maximum of the saturation magnetization, micro-hardness and electrochemical impedance (MS ≈1201.1 kA/m, HV ≈425.4 kg/mm 2 , Z � ≈400 Ω) and the minimum of the coercivity (HC ≈2.1 kA/m) appeared at 250 . Thus, the alloy coating heated at 250 possesses best soft magnetic performance and corrosion resistance.