Effect of Co content on the microstructure, mechanical properties and corrosion behavior of Zr alloys

The microstructure, mechanical properties and corrosion properties of Zr-xCo (x = 0, 2, 4, 6, 8, 10 at.%) binary alloys have been systematically studied. The microstructure of the alloy was analyzed by optical microscope, X-ray diffractometer, scanning electron microscope, transmission electron microscope and electron probe, and the existence of Zr3Co phase was found. The mechanical properties of the alloy were analyzed by compressive stress-strain test and Vickers hardness test. It was found that the addition of Co improved the strength of the alloy, and the ductility of the alloy was the best when the content of Co reached 6 at.%. Through electrochemical experiments, the corrosion properties of the alloy were analyzed, and it was found that the addition of Co had an active influence on the corrosion resistance of the alloy, which made the passivation film formed by the sample denser, and effectively alleviated the corrosion behavior of the alloy. Surface potential analysis was performed with atomic force microscope. Through X-ray photoelectron spectroscopy analysis of passive film, it is revealed that passive film mainly consists of ZrO2, Co3O4, Co(OH)2 and Zr2O3.