Microstructure and Surface Corrosion Behavior of Plasma Welding Area of Al3Zr/Al Matrix In-situ Composites

5 wt% Al3Zr/aluminum matrix composites were taken as the research object, and plasma welding was conducted with Ar gas as ion gas and Al-Ti-B as wire materials. The corrosion polarization curve of weld area in 3.5% NaCl solution was measured by electrochemical comprehensive tester. Scanning electron microscope (SEM) and X-ray diffraction analyzer (XRD) were used to analyze and characterize the microstructure and phase composition of the composite and its weld. The corrosion behavior and corrosion mechanism of Al3Zr/aluminum matrix composites after plasma welding were studied in 3.5% NaCl solution. The SEM analysis results show that through plasma arc welding, a better weld can be obtained. The weld microstructure is mainly composed of Al3Ti phase and Al matrix, and the Al3Ti phase is striped and spherical. The electrochemical polarization curves indicate that the corrosion resistance of the materials at the nugget is slightly lower than that of the base metal. The immersion corrosion mechanism of weld is that the Al3Ti phase and the matrix phase behave as the anode and cathode of a primary cell.