Mechanical alloying of Cu and Fe induced by severe plastic deformation of a Cu-Fe composite

TL;DR

This study demonstrates that severe plastic deformation via High Pressure Torsion can induce nanoscale dissolution of Fe in Cu, creating supersaturated solid solutions despite low equilibrium solubility.

Contribution

It reveals that severe plastic deformation causes non-equilibrium alloying of Cu and Fe by increasing vacancy concentration and atomic mobility.

Findings

Fe clusters dissolve in Cu matrix during HPT

Supersaturated Cu-Fe solutions contain up to 20 at.% Fe

Vacancy concentration increases dramatically during SPD

Abstract

A filamentary composite elaborated by cold drawing was processed by High Pressure Torsion (HPT). The nanostructure resulting from this severe plastic deformation (SPD) was investigated thanks to scanning electron microscopy, transmission electron microscopy, X-ray diffraction and 3D atom probe. Although the mutual solubility of Cu and Fe is extremely low at room temperature in equilibrium conditions, it is shown that nanoscaled Fe clusters dissolve in the Cu matrix. The non-equilibrium copper supersaturated solid solutions contain up to 20at.% Fe. The driving force of the dissolution is attributed to capillary pressures and mechanisms which could enhanced the atomic mobility during HPT are discussed. We conclude that the interdiffusion is the result of a dramatic increase of the vacancy concentration during SPD.