Extension of Solid Solubility and Structural Evolution in Nano-Structured Cu-Cr Solid Solution Induced by High-Energy...

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• Strengthening in copper-chromium (Cu-Cr) alloys is limited by low chromium (Cr) solid solubility in copper (Cu).
• Undissolved Cr acts as a second phase, impacting alloy performance.
• Nanostructuring Cr phases and increasing solubility are key to enhancing Cu-Cr alloys.

Purpose of the Study:

• To achieve nano-sized Cu-Cr solid solutions.
• To extend Cr solid solubility in the Cu matrix.
• To refine the size of undissolved Cr phases to the nanoscale.

Main Methods:

• High energy ball milling (HEBM) of Cu-5 wt.% Cr powders.
• X-ray diffraction (XRD) pattern analysis for solubility calculation.
• Microstructural analysis of crystallite and grain size evolution.

Main Results:

• Nano-sized Cu-Cr solid solution achieved within 12 hours of HEBM.
• Quantified Cr solubility of ~1.15 at.%, indicating a supersaturated solid solution.
• Undissolved Cr phases were refined to nano-sized dimensions.
• Significant reduction in crystallite and grain sizes observed with milling time.

Conclusions:

• HEBM effectively creates supersaturated Cu-Cr solid solutions.
• The process refines Cr phases to the nanoscale, enhancing dispersion strengthening.
• Stored energy from dislocation density and grain refinement overcomes thermodynamic barriers for solid solution formation.