Abstract
AbstractNano-crystalline (nc) Cu with Cr2O3dispersoid (~4 vol.%) was successfully made by reactive-milling at 210 K with a mixture of pure Cu, Cu2O, and Cr powder. The vacuum hot pressing (HP) was performed at 1123 K and 50 MPa for 2h to consolidate the milled powder for further analysis. TEM (Transmission Electron Microscopy) work revealed that the HPed materials were comprised with a mixture of the nc-Cu and a homogeneous distribution of Cr2O3dispersoids. The microstructure and Vickers hardness of the as-milled powder and the HPed materials were characterized by standard metallographic techniques. The grain size of the Cu was measured using Scherrer’s formula (XRD) and TEM observation; the Cr2O3dispersoid size was estimated from the HADDF (High Angle Annular Dark Field) images and element mapping by STEM-EDS (Scanning Transmission Electron Microscopy-Energy Dispersive Spectroscopy) works. The formation kinetics and coarsening of the Cr2O3dispersoids in Cu matrix were discussed based on the calculations with thermodynamic parameters in comparison with those of Al2O3.
Highlights
Oxide dispersion strengthened (ODS) Cu-based alloys have been paid much attentions for their good thermal, electrical, and mechanical properties in the fields of nuclear, electronic, and spot welding in auto industry [1, 2]
TEM (Transmission Electron Microscopy) work revealed that the HPed materials were comprised with a mixture of the nc-Cu and a homogeneous distribution of Cr2O3 dispersoids
A XRD pattern of Figure 2 is from the HPed materials; presence of only Cu and Cr2O3 peaks is obvious, suggesting that the formation of the desired phases has been attained after hot pressing (HP)
Summary
Oxide dispersion strengthened (ODS) Cu-based alloys have been paid much attentions for their good thermal, electrical, and mechanical properties in the fields of nuclear, electronic, and spot welding in auto industry [1, 2]. The Y2O3 dispersoids has an attraction for the highest enthalpy of formation to keep themselves to be fine and small; Al2O3 dispersoids has a forte for the versatile processing (the internal oxidation and/or Mechanical Alloying). It seems that insufficient examination has been made to take advantage of using Cr2O3 instead of Al2O3 or Y2O3. The formation kinetics of the dispersoids is analyzed in terms of thermodynamic consideration; the coarsening behavior of the dispersoids at the processing temperature (HP) is discussed along with the results of TEM observations
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