Thermal expansion behavior, microhardness and electrochemical corrosion resistance properties of Au52Cu27Ag17-x(NiZn0.5)x alloys
(1. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials,
Ministry of Education, Shandong University, Ji’nan 250061, China;
2. Shandong Institute of Metrology, Ji’nan 250014, China)
Ministry of Education, Shandong University, Ji’nan 250061, China;
2. Shandong Institute of Metrology, Ji’nan 250014, China)
Abstract: The thermal expansion behavior, microhardness and electrochemical corrosion resistance of Au52Cu27Ag17-x(NiZn0.5)x (x=0, 6 and 12) alloys were investigated by dilatometer (DIL), microhardness tester, electrochemical workstation, X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). With increasing x, the relative length expansion and DIL maximum temperature Tl m (i.e., thermal stability) of the alloys increase in thermal expansion measurements, which can be explained by the change of the atomic binding energy, mismatch entropy together with phase transformation. With the increase of x, the microhardness can be improved, but the corrosion resistance decreases; in addition, the anodic peak current densities of polarization curves decrease, which are related closely with the solid solution degree and dissolution of Ag, Ni and Zn alloying elements in Cl--containing solution.
Key words: gold alloy; thermal expansion; microhardness; corrosion resistance