Spinodal decomposition and precipitation in Cu–Cr nanocomposite

•Precipitation mechanism of supersaturated Cu-Cr solid solutions was investigated.•Precipitation begins with spinodal decomposition and ends with nucleation and growth.•Kinetics of decomposition is faster in presence of Al2O3 nano-particles. In this study, spinodal decomposition and precipitation me...

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Bibliographic Details
Published in:Journal of alloys and compounds 2014-02, Vol.587, p.670-676
Main Authors: Sheibani, S., Heshmati-Manesh, S., Ataie, A., Caballero, A., Criado, J.M.
Format: Article
Language:English
Subjects:
ALUMINUM OXIDE
CALORIMETRY
Condensed matter: structure, mechanical and thermal properties
Copper
COPPER ALLOYS (40 TO 99.3 CU)
Copper base alloys
Cross-disciplinary physics: materials science
rheology
DECOMPOSITION
Differential scanning calorimetry
Equations of state, phase equilibria, and phase transitions
Exact sciences and technology
Kinetics
Materials science
Mechanical alloying
MICROSTRUCTURES
Nanocomposite
Nanostructure
Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
Physics
Precipitation
SOLID SOLUTIONS
Solubility, segregation, and mixing
phase separation
Spinodal decomposition
Transmission electron microscopy
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Summary:•Precipitation mechanism of supersaturated Cu-Cr solid solutions was investigated.•Precipitation begins with spinodal decomposition and ends with nucleation and growth.•Kinetics of decomposition is faster in presence of Al2O3 nano-particles. In this study, spinodal decomposition and precipitation mechanism of mechanically alloyed supersaturated Cu–3wt.%Cr and Cu–5wt.%Cr solid solutions was investigated under nonisothermal aging. Decomposition mechanism and kinetics were studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. Also, the microstructure was characterized by transmission electron microscopy (TEM). Effect of Al2O3 reinforcement on the aging kinetics was also evaluated. It was found that Cu–3wt.%Cr and Cu–5wt.%Cr solid solutions undergo spinodal decomposition at initial stages of ageing. However, decomposition mechanism was changed to nucleation and growth by the aging progress. The aging kinetics for the Cu–Cr/Al2O3 composition appeared to be slightly faster than that for Cu–Cr, since the ageing activation energy is decreased in presence of Al2O3 nano-particles. This behavior is probably due to the higher dislocation density and other structural defects previously produced during ball milling. A detailed comparison of the DSC results with those obtained by TEM, showing good consistency, has been presented. The average size of Cr-rich precipitates was about 10nm in the copper matrix.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2013.11.019