Magnetic field effects on electrochemical dissolution behavior and surface quality of electrochemical machining of Ti-48Al-2Cr-2Nb alloy

Magnetic field as a simple and powerful tool is usually applied to electrochemical machining, but the influencing mechanism is a very complicated problem. Ti-48Al-2Cr-2Nb (at. %) alloy dissolution behavior without and with magnetic field was carried out. Open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), cyclic potentiodynamic polarization (CPP), chronoamperometry (CA), and observation of corrosion morphology combined with energy spectrum analysis were applied. In addition, multifractal spectrum and surface roughness were used to evaluate uniformity and roughness of surface topography of the electrochemical machining (ECM) of Ti-48Al-2Cr-2Nb alloy. The results prove that the magnetic field improves the response rate of adsorption reaction, enhances the decomposition potential and the sensitivity to local corrosion, suppresses the fluctuation of the current density, and reduces the dissolution rate during electrochemical corrosion of Ti-48Al-2Cr-2Nb alloy. The results also verify that the improvement of magnetic field on uniformity of corrosion contributes to obtain an isotropic microscopic surface in the electrochemical machining of Ti-48Al-2Cr-2Nb alloy. The surface roughness of the electrochemical machined surface of Ti-48Al-2Cr-2Nb alloy without and with magnetic field is Ra 2.46 +/- 0.14 mu m and 1.73 +/- 0.28 mu m, respectively, which confirms that the deterioration in the preferential corrosion of gamma-TiAl phase caused by magnetic field does not become a detrimental factor in obtaining a smooth machined surface. So, magnetic field has a positive effect in the electrochemical machining process of Ti-48Al-2Cr-2Nb alloy and can be applied to the actual production.