Phase Transitions of Cu and Fe at Multiscales in an Additively Manufactured Cu-Fe Alloy under High-Pressure

A state of the art, custom-built direct-metal deposition (DMD)-based additive manufacturing (AM) system at the University of Michigan was used to manufacture 50Cu-50Fe alloy with tailored properties for use in high strain/deformation environments. Subsequently, we performed preliminary high-pressure compression experiments to investigate the structural stability and deformation of this material. Our work shows that the alpha (BCC) phase of Fe is stable up to similar to 16 GPa before reversibly transforming to HCP, which is at least a few GPa higher than pure bulk Fe material. Furthermore, we observed evidence of a transition of Cu nano-precipitates in Fe from the well-known FCC structure to a metastable BCC phase, which has only been predicted via density functional calculations. Finally, the metastable FCC Fe nano-precipitates within the Cu grains show a modulated nano-twinned structure induced by high-pressure deformation. The results from this work demonstrate the opportunity in AM application for tailored functional materials and extreme stress/deformation applications.

Automated summary

In this study, a state-of-the-art additive manufacturing system was used to produce a custom-built 50Cu-50Fe alloy. High-pressure compression experiments were conducted to investigate the structural stability and deformation of the material. The results showed that the Fe phase remained stable up to a certain pressure, while Cu undergoes a structural transition. This work highlights the potential of additive manufacturing for tailored functional materials and extreme stress/deformation applications.