3D Impedance Analysis on Dissolution Behavior of Additive-Manufactured Al-12%Si Alloy

Abstract

Laser Powder Bed Fusion (LBPF) is one of the additive manufacturing techniques using a laser beam to melt and fuse layers of metal powder particles forming various metal products with complex shapes. Because the Al-Si alloy manufactured by LPBF has good mechanical properties compared to conventionally cast Al alloys, it is important to investigate the dissolution behavior of Al-Si alloy manufactured by LPBF for wider usage in industry.In the present study, the film resistance of oxide film formed on additive-manufactured Al-12%Si alloys were investigated by a three-dimensional(3D) impedance spectroscopy1-5. This method allows for the estimation of the film resistance with time information because the impedance is plotted on the 3D diagram whose axes are real, imaginary and time, namely, the instantaneous impedance at arbitrary time can be determined from 3D impedance. To investigate the dissolution behavior of additive-manufactured Al alloys, the non-annealed sample (Al-12Si) and annealed samples at different temperatures ranging from 200 to 350 ℃ (Al-12Si300) and 530 ℃ (Al-12Si530) with arbitrary holding time were used for the electrochemical measurements. The 3D impedance of Al-12Si, Al-12Si300 and Al-12Si530 could be successively measured in the immersion conditions. The 3D impedance of Al-12Si and Al-12Si300 demonstrated that the impedance of both samples was increased with time. The 3D impedance of Al-12Si530 indicated small values during measurement. These results imply that the increase of impedance of Al-12Si and Al-12Si300 is associated with the formation of oxide film on the surface. The film resistance estimated from impedance spectra determined from 3D impedance and the morphology of samples after the measurement were correlated discussed.