New insights on the formation of supersaturated solid solutions in the Cu Cr system deformed by high pressure torsion

TL;DR

This study investigates how severe plastic deformation induces supersaturated solid solutions in the Cu-Cr system, revealing microstructural evolution, stability, and hardness enhancements through advanced diffraction and microscopy techniques.

Contribution

It introduces a new energy dispersive Rietveld analysis method to quantify microstructural parameters during deformation, providing deeper insights into supersaturation mechanisms.

Findings

Supersaturated solid solutions form during high pressure torsion in Cu-Cr.

Deformed samples exhibit high thermal stability and increased hardness.

Microstructural evolution is characterized by lattice parameter and domain size changes.

Abstract

In the Cu Cr system, the formation of supersaturated solid solutions can be obtained by severe plastic deformation. Energy dispersive synchrotron diffraction measurements on as deformed Cu Cr samples as a function of the applied strain during deformation confirm the formation of supersaturated solid solutions in this usually immiscible system. Due to evaluation of the diffraction data by a newly developed energy dispersive Rietveld program, lattice parameter and microstructural parameters such as domain size and microstrain are determined for as deformed as well as annealed samples. The obtained information is used to deepen the understanding of the microstructural evolution and the formation of supersaturated solid solutions during severe plastic deformation. Complimentary transmission electron microscopy investigations are furthermore performed to characterize the evolving microstructure in detail. After annealing at elevated temperatures, the formed solid solutions decompose. Compared to the as deformed state, an enhanced hardness combined with a high thermal stability is observed. Possible mechanisms for the enhanced hardness are discussed.