Oxide-stabilized microstructure of severe plastically deformed CuCo alloys

TL;DR

This study investigates how oxide formation and microstructure stabilization occur in severely plastically deformed CuCo alloys during annealing, revealing oxide growth dynamics and their role in microstructure stability.

Contribution

It provides new insights into oxide evolution and microstructure stabilization in CuCo alloys subjected to severe plastic deformation and annealing.

Findings

Oxide growth and formation are monitored during annealing.

Different oxide amounts influence coarsening behavior.

Major oxides are present in initial materials.

Abstract

Nanocrystalline materials are well known for their beneficial mechanical and physical properties. However, it is of utmost importance to stabilize the microstructure at elevated temperatures to broaden the window of application e.g. by pinning grain boundaries through impurities or oxides. CuCo alloys, severe plastically deformed using high-pressure torsion, were used to investigate the evolution of oxides upon annealing. These investigations were performed using electron microscopy, synchrotron high-energy X-ray scattering and atom probe tomography. Monitoring the evolution of oxides by in-situ small angle scattering investigations indicates the growth of primary oxides as well as the formation of another species of oxide at elevated temperatures. Slightly different coarsening can be observed in heat-treated samples, which can be traced back to the influence of different oxide amounts. The initially supersaturated CuCo matrix changes by the decomposition process as well as Co- and Cu-based oxides formation and growth. It has been found that the major number of oxides which are present after annealing, can already be found in the starting materials.