Magnesium addition in copper‐chromium alloys: The refinement of aging precipitates and improvement on mechanical properties

Abstract

Herein, we demonstrate the synthesis of copper‐chromium and copper‐ chromium‐magnesium alloys by melting and casting process and explore the effect of the magnesium addition on mechanical and electrical properties of the alloys. This article focuses on the variation of the precipitation sequence and the decrease of strengthening phase sizes induced by the addition of trace magnesium element. The results show that magnesium element has little effect on the hardness of copper‐chromium alloy, but it significantly improves the hardness of the aging alloy and maintains high conductivity. The addition of magnesium element inhibits the growth and structural transformation of the precipitated phase. The refinement impact of magnesium addition on precipitated phase and change in alloy precipitation sequence may be the main reasons for the high hardness of copper‐chromium‐ magnesium alloy. In addition, the magnesium addition shows a significant refinement effect on small size precipitation phase, but it does not present the same refinement effect on large size precipitation phase. This attributes to the presence of a semi‐coherent interface between the matrix and the large size of precipitates, which provides the dislocation‐based diffusion channels for high‐rate chromium diffusion and promotes the precipitate growth.

Effect of grain boundary migration in Cu–Cr–Zr–Ti manufactured using different casting processes

“…In addition, the semifinished products made by horizontal continuous casting have better surface qualities, including smaller defects and cracks. Nevertheless, segregation of chemical composition often occurs in the alloy products during the horizontal continuous casting process, which leads to the deterioration of the mechanical properties [13][14][15][16]. The casting, extrusion, and drawing process is a traditional manufacturing method for Cu-based alloy rod production and it can produce Cu-based alloy rods with an equiaxed structure.…”