Microsc. Microanal. Microstruct. 6, 601-609 (1995)
DOI: 10.1051/mmm:1995150

Electron Microscopy Investigation on the Effect of Plastic Deformation in the Alloying of the Immiscible System Cu-Fe

Massimo Angiolini, Francesco Cardellini, Marek Krasnowski, Giorgio Mazzone, Amella Montone et Marco Vittori-Antisari

ENEA, C.R. Casaccia. INN-NUMA, C.P. 2400, 00100 Roma, Italy

Abstract
The first steps of the solid state reaction between Cu and Fe induced by plastic deformation at low temperature have been studied by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). Despite the positive enthalpy of mixing, plastic deformation induces interdiffusion in this system as evidenced by XRD and DSC analysis. TEM observations of samples prepared in different ways show the presence of some Fe into the Cu matrix, a relatively low density of dislocations, a large concentration of small agglomerates of point defects and a well-defined grain shape, suggesting that some dynamic recrystallization occurs during deformation. Considering the low processing temperature we advance the hypothesis that the excess concentration of point defects induced by the high strain rate plastic deformation can provide the necessary atomic mobility. Moreover the role played by these defects on the thermodynamic driving force of the alloying process is considered.

PACS
8140L - Deformation, plasticity and creep.
6220F - Deformation and plasticity.
6475 - Solubility, segregation, and mixing.
6630N - Chemical interdiffusion in solids.
6822 - Surface diffusion, segregation and interfacial compound formation.
6170J - Etch pits, decoration, transmission electron microscopy and other direct observations of dislocations.
8140E - Cold working, work hardening: post deformation annealing, recovery and recrystallisation: textures.
6170B - Interstitials and vacancies.
8120E - Powder techniques, compaction and sintering.
8120G - Preparation of metals and alloys compacts, pseudoalloys.
6550 - Thermodynamic properties and entropy.

Key words
chemical interdiffusion -- copper alloys -- dislocation density -- heat of mixing -- iron alloys -- mechanical alloying -- plastic deformation -- point defects -- powder metallurgy -- recrystallisation -- solid solubility -- thermal analysis -- transmission electron microscopy -- X ray diffraction -- electron microscopy -- plastic deformation -- alloying -- immiscible system -- Cu Fe -- solid state reaction -- low temperature -- transmission electron microscopy -- TEM -- X ray diffraction -- XRD -- differential scanning calorimetry -- DSC -- positive enthalpy of mixing -- interdiffusion -- dislocation density -- agglomerates -- point defects -- well defined grain shape -- dynamic recrystallization -- low processing temperature -- high strain rate plastic deformation


© EDP Sciences 1995