Microstructural analysis and corrosion behavior of Fe, B, and Fe-B-modified Cu-Zn-Al shape memory alloys

Abstract

AbstractThe corrosion behavior of Cu-Zn-Al alloys modified with Fe, B, and Fe-B was investigated. This was motivated by the need to verify the effect of microalloy additions on the corrosion behavior of Cu-Zn-Al alloys, which, as recent study suggests, impacts microstructural changes other than grain refinement. Cu-Zn-Al alloys were produced by casting method with and without the addition of microalloy elements. The alloys were subjected to thermomechanical treatment before machining of test samples for corrosion and microstructural analysis. Scanning electron microscopy (SEM) and polarization electrochemical technique were used for the study. From the results, increase in grain size and change in grain edge morphology was apparent for the modified Cu-Zn-Al alloys produced. In 3.5 wt.% NaCl and 0.3 m H2SO4 solutions, the corrosion current densities were dependent on the type and concentration of the microalloy addition. Essentially, the corrosion rates for the modified alloys were higher in 3.5 wt.% NaCl solution; in 0.3 m H2SO4 solution, the modified Cu-Zn-Al alloy grades were observed to be more resistant to corrosion. The corrosion mechanisms of the alloys in both solutions were not feasibly established from the SEM images, but the extent of corrosion product deposition was apparent.