Investigation on the Microstructure and Electrochemical Corrosion Properties of TiB2 reinforced aluminum matrix composites

The TiB2 particles reinforced AlSi10Mg composites were prepared by selective laser melting (SLM). The effect of TiB2 particles on the microstructure and electrochemical corrosion properties of the Al-based composites was studied. The phase structure was examined by X-ray diffraction (XRD). The morphology was observed by the metallographic microscope and scanning electron microscope. The corrosion behavior was evaluated by Potetiodynamic polarization and electrochemical impedance spectroscopy. In this experiment, the corrosion resistance of TiB2 aluminum matrix composites with different contents in 3.5 % NaCl solution at 25 degrees C (room temperature) was mainly tested. Firstly, the addition of TiB2 can effectively improve the morphology of the molten pool. Secondly, the addition of TiB2 will change the corrosion type of Al matrix composites: from uniform / comprehensive corrosion to pitting corrosion, which is easy to occur around TiB2 particles. Through the experimental data, it was observed that the corrosion potential of the sample was positively shifted by adding TiB2, and the electrochemical stability was improved. The addition of TiB2 can effectively reduce the corrosion tendency of the samples. When the content of TiB2 increases to 5 %, the pitting corrosion occurs seriously, and when TiB2 is added to 15 %, the corrosion resistance of the samples increases again.