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.
Highlights
Copper and copper alloys are widely used in engineering because they have excellent properties, good electrical and thermal conductivity, excellent resistance to corrosion, and they are easy to manufacture [1]
A new method that can be used for the formation of this alloy, is Mechanical Alloying (MA), a simple and versatile method due to its ability to increase the free energy of the system and solid solubility at room temperature [3,4], through the high transfer of energy that occurs between the milling media and the powders to be alloyed [5]
Mechanical alloying is a good technique for the formation of immiscible alloys in solid state, Cu
Summary
Copper and copper alloys are widely used in engineering because they have excellent properties, good electrical and thermal conductivity, excellent resistance to corrosion, and they are easy to manufacture [1]. Many copper-based binary systems, such as Cu–Mo, appear to be immiscible in the solid and liquid state, and they do not form any compound or alloy using conventional methods [2]. Copper-base alloys have been widely used in the maritime area, such as in condenser tubes, immersion equipment, and underwater robots [11,12,13]. For this kind of alloy, it is important to know the corrosion behavior as well as the speed at which the process occurs in order to determine their behavior in different saline environments [14]
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