Effects of different Cr contents on the microstructure, mechanical and electrical properties of Cu-Mg-Cr alloy

Cu-0.16Mg- x Cr ( x =0, 0.1, 0.2, 0.3 wt.%) alloy wires were prepared through vacuum melting and casting, hot forging, drawing, and heat treatment processes. The effects of Cr contents on the microstructure evolution, mechanical properties, and electrical properties of Cu-Mg-Cr alloys were investigated. The addition of Cr significantly refined the as-cast and as-processed microstructures comparing to the binary Cu-Mg alloy, and formed coherent nano-sized Cr-rich precipitates within the matrix in the microstructure, these Cr-rich precipitates maintain a cube-on-cube relationship with the Cu matrix, thereby creating a coherent interface that acts as an immovable barrier. This process effectively stabilizes dislocations, suppresses dynamic recrystallization, and promotes an increase in dislocation density.. The grain size in the alloy structure gradually decreases, while the proportion of low-angle grain boundaries (LAGBs) and the volume fractions of deformation fiber textures (Copper{112} and Brass{011} fiber textures) increase with Cr contents increasing. The deformation fiber textures with low Schmid factor interact with precipitation, hindering the initiation of dislocation slip systems and improving the tensile strength of the alloy. The Cu-0.16Mg-0.3Cr alloy wire exhibited the best combination of mechanical and electrical properties with 853.4 MPa tensile strength and 76% IACS electrical conductivity.