In-situ observation of microstructure and orientation evolution of the Cu-Cr-Zr-Hf alloys

The roles of Hf element in the mechanical properties, deformation mode and orientation evolution of the Cu0.4Cr-0.2Zr-0.2Hf (wt.%) alloys were investigated using both ex-situ and in-situ electron backscatter diffraction (EBSD). The results indicate that the trace Hf element (0.2 wt%) addition into the Cu-Cr-Zr alloys motivates the multiple slip activities. The activation of multiple slip systems indirectly or directly influences the tensile strength, strain distribution and lattice rotation. Firstly, it promotes the generation of dislocations, and thus enhances the work hardening rate, contributing to the improvement of the ultimate tensile strength. Secondly, it inhibits the movement of dislocations to the grain boundaries, and thus hinders the strain localization at the grain boundaries, promoting the homogeneous deformation. Thirdly, the interaction between dislocations on different slip systems restricts the intragranular lattice rotation, leading to the high stability of the grains with Goss orientation in the Cu-Cr-Zr-Hf alloys. The mutual transform between the R-CubeRD orientation and Goss orientation is also observed. This study deepens the understanding of deformation mechanisms and texture evolution of the Cu-Cr-Zr-Hf alloys.