Microstructural evolution and properties of the Cu-Cr-Ti alloys after cold deformation and subsequent aging treatment

Abstract

The increasingly desirable mechanical and physical properties limits the application of traditional Cu-Cr alloys, and deserves the compositional design and processing optimization of Cu-Cr-Ti alloys. The effects of cold deformation and aging treatment on the microstructures and properties of the Cu-0.2Cr-0.08Ti alloys were investigated. The shapes of precipitates and evolution of dislocations in the specimens with increasing deformation amounts and aging times was uncovered, and the strengthening mechanisms of Cu-Cr-Ti alloys were elucidated by using TEM and HRTEM analysis. When the deformation amount is not higher than 40 ​%, the increased deformation amounts increases the dislocation density in the Cu-0.2Cr-0.08Ti alloy, promoting the formation of dislocation cell and dislocation tangles with small size. The precipitation of fine Cr particles coherent with Cu matrix is accelerated, accompanied by the enhancement of microhardness and electrical conductivity. The Cu-0.2Cr-0.08Ti alloy with 40 ​% deformation amounts after aging at 480 ​°C for 1 ​h has the optimal comprehensive properties, which is related to the increasing dislocation density, the refinement of Cu grains and the precipitation of Cr particles. The enhanced strength of Cu-0.2Cr-0.08Ti alloy with 40 ​% deformation amounts after aging at 480 ​°C for 1 ​h is attributed to the solute strengthening of solute atoms, precipitate strengthening of fine Cr particles, dislocations strengthening and grain boundary strengthening mechanisms.