Nucleation and growth of gamma-Fe precipitate in Cu-2% Fe alloy aged under high magnetic field

摘要

Cu-2wt% Fe alloy, an inexpensive candidate for a high strength conductor, depends for its conductivity on the precipitation of Fe. We applied an external 12 T high magnetic field (HMF) during ageing treatment of this alloy in order to study the resulting gamma-Fe precipitation on the electrical conductivity. When the alloy was aged at 450 degrees C for up to 16 h, coherent gamma-Fe precipitates formed within the Cu matrix. Between the gamma-Fe precipitates and the Cu matrix, the lattice misfit was 1.4% +/- 0.7% and the angle between closed packed planes was about 0.3 degrees. These gamma-Fe precipitates became semi-coherent with the surrounding Cu matrix in samples aged at 700 degrees C for over 0.5 h. HMF made insignificant contributions to both the morphology and the volume fraction of gamma-Fe at 450 degrees C. At 700 degrees C, however, HMF promoted a transformation from coherent to semi-coherent gamma-Fe precipitates. Applying HMF during ageing at 700 degrees C increased electrical conductivity. HMF had little influence on the nucleation of gamma-Fe precipitation. We applied the Lifshitz-Slyozov-Wagner (LSW) formula to the coarsening data of the precipitates and determined that HMF increased the diffusion coefficient of Fe in Cu and promoted the growth of gamma-Fe precipitation out of the Cu matrix. (C) 2015 Elsevier B.V. All rights reserved.