Effects of SIMA (Strain Induced Melt Activation) on microstructure and electrochemical behavior of Al-Zn-In sacrificial anodes

The Strain Induced Melt Activation (SIMA) process is one of the semi-solid forming processes for preparation of non-dendritic microstructures. In current work, the effects of SIMA process on microstructure and electrochemical behavior of Al-Zn-In sacrificial anode were studied. The effect of plastic deformation on the semi-solid microstructure of Al-Zn-In alloy is investigated by applying 10-40% uniaxial compression at ambient temperature and semi-solid treatment was carried out in the range of 635-660 °C for 40 min. Investigation of the electrochemical behavior of anode and Tafel polarization test are performed in 3.5 wt% sodium chloride solution. The results indicate that microstructure of the SIMA processed specimens is finer and more spherical than that of the as-received material. The sphericity increases significantly with the increase of the compression ratio from 10 to 30%, but the variation rate of the average grain size increases and the shape factor decreases with more increase of the compression ratio up to 40%. The average size and sphericity of α-Al solid grains increase with the increase of the heat treatment temperature. Electrochemical tests results show that plastic deformation up to 30% following heat treatment at 650 °C increases the anode efficiency. Furthermore, SEM results indicated uniform corrosion under the aforementioned condition.