Effects of Small Amount Addition of Rare Earth Ce on Microstructure and Properties of Cast Pure Copper

摘要

The effects of small amount addition of the rare-earth Ce on the microstructure, mechanical properties, and corrosion resistance behavior of cast pure copper were investigated using optical microscopy, scanning electron microscopy, energy-dispersive x-ray spectrometry (EDS), transmission electron microscopy (TEM), tensile testing, and potentiodynamic polarization measurements. It was indicated that Ce addition significantly refined the grain and enhanced the tensile strength of cast pure copper. Copper alloy with 0.12 wt.% Ce addition had the smallest equiaxed grains of 358. +/- A 23.53 mu m and the ultimate tensile strength of 181.7 +/- A 3.7 MPa. Ce formed spherical second phase particles with copper, which were revealed as Cu6Ce by EDS and TEM results. Solid solution strengthening, fine-grain strengthening, and second-phase precipitation strengthening played important roles in the tensile strength improvement. However, the elongation decreased due to the second phase particles' inhomogeneous distribution. The corrosion resistance properties of micro-alloyed copper alloys in 0.5 mol/L HCl solution were improved when Ce addition was limited to less than 0.069 wt.% owing to a purification effect and the formation of a compact corrosion product film on the copper matrix. The influencing mechanisms of Ce on the microstructure, mechanical property, and corrosion property were also discussed in detail.