Orientation relationships between precipitates and matrix and their crystallographic transformation in a Cu–Cr–Zr alloy

The orientation relationships between Cr precipitates and matrix in a Cu–Cr–Zr alloy with various aged states were investigated by transmission electron microscopy and High-resolution transmission electron microscopy, and the crystallographic transformations of orientation relationships were also analyzed by stereographic projection and discussed. Four kinds of orientation relationships were detected in the precipitation process of Cu–Cr–Zr alloy, and coexistence of Cr precipitates with Nishiyama-Wassermann relationship and Pitsch relationship was found in the peak-aged Cu–Cr–Zr alloy. The occurrence for cube-on-cube and Pitsch relationship in Cu–Cr–Zr alloy was thought to be caused by the retardation of additions and heterogeneous nucleation of Cr precipitates on dislocations respectively. Transformations of orientation relationships were observed during precipitation and the crystallographic rotation pathways of the transformations were represented by stereographic projection. The interrelationships of various orientation relationships were established by Bain strain and crystal rotation in the Cu–Cr–Zr alloy of this study. • Four kinds of ORs were detected during precipitation of Cu–Cr–Zr alloy. • Coexistence of N–W and Pitsch orientation was found in peak-aged Cu–Cr–Zr alloy. • Formation of Pitsch relationship may be related to heterogeneous nucleation. • Rotation pathways of ORs transformation are represented by stereographic projection. • Interrelationships of various ORs are established by Bain strain and crystal rotation.