Study of Zr addition on the composition, crystallite size, microstructure and properties of high-performance nano Cu alloys prepared by mechanical alloying

Abstract

Although nanostructured Cu alloys prepared show great advantages in performance, the excellent properties have not been achieved at present primarily due to a single strengthening method or the Fe contamination introduced during mechanical alloying. In the present work, an appropriate amount of Zr was added to adjust the milling process and Fe contamination in the Cu matrix. Then the effects of Zr on the morphologies, crystallite sizes, lattice strain, composition and properties were analyzed. When the added Zr content was 0.1 wt%, it could promote the work hardening of Cu powders, resulting in smaller crystallite sizes, larger internal strain. And a slightly higher Fe content was introduced. However, with the increase of the Zr content, the Fe contamination was reduced obviously and the crystallite size began to increase again. Even so, the average crystallite sizes of nanostructured Cu alloys were still less than 20 nm. The results also showed that MA could increase the solid solubility of Zr in Cu. In a word, the properties of the nanostructured Cu alloys were improved by the refinement strengthening of matrix, solid solution and dispersion strengthening of Fe and Zr. The optimum properties were achieved by Cu-0.1 wt% Zr with electrical conductivity of 75.19% IACS and tensile strength of 526 MPa. The study provided a new route for overcoming Fe contamination in the metal matrix, and further improving the properties of Cu alloys through various strengthening methods.