Effects of Mo Concentration on the Structural and Corrosion Properties of Cu–Alloy

Abstract

Mechanical Alloying (MA) has the ability to extend the solubility limits of immiscible alloys in a solid state. In this work, a Cu-10 wt% Mo alloy was synthesized by mechanical alloying, using a high-energy mill type SPEX. The X-ray diffraction and Rietveld results show a crystallite size of 24 and 22 nm of Cu and Mo, respectively, with an occupation value of Mo inside the Cu structure of 27%, which was identificated by Energy Dispersive X-ray Spectroscopy and High-Resolution Transmission Electron Microscopy analysis. After that, the alloy was sinterized in an oven, heating the alloy to 1000 °C—close to the melting point of Cu (1085 °C). Electrochemical tests were carried out under a saline environment of synthetic seawater. The results show that the polarization curve of the alloy showed a pitting corrosion at about 134.83 mV, as well as a repasivation phenomenon (Erp = 241.47 mV) in the cathodic branch. Finally, three time constants were observed in the Nyquist diagrams: formation of a corrosion product film, load transfer, and diffusion, indicating that the corrosion properties in this alloy were improved compared with other Cu–alloys.