APT analysis of WC-Co based cemented carbides.

Area of Science:

• Materials Science
• Analytical Chemistry
• Physical Metallurgy

Background:

• Tungsten carbide-cobalt (WC-Co) cemented carbides are critical industrial materials.
• Understanding interface chemistry and solute behavior is essential for optimizing performance.
• Previous methods for atom probe specimen preparation and interface analysis were limited.

Purpose of the Study:

• To develop a rapid and site-specific method for preparing atom probe specimens from WC-Co.
• To establish a technique for quantifying atom segregation at interfaces with varying field evaporation requirements.
• To analyze the interface chemistry and determine transition metal solubility in WC.

Main Methods:

• Combined electropolishing, controlled back-polishing, and focused ion beam (FIB) milling for specimen preparation.
• Developed a novel method for measuring segregated atoms at interfaces with significant field evaporation differences.
• Utilized atom probe tomography (APT) for high-resolution chemical analysis of interfaces.

Main Results:

• Successfully produced sharp, site-specific atom probe specimens from WC-Co.
• Quantified atom segregation at WC/WC grain boundaries, WC/(M,W)C phase boundaries, and WC/binder phase boundaries.
• Determined the solubility of transition metals within the WC phase.

Conclusions:

• The developed APT method enables precise characterization of WC-Co microstructure and chemistry.
• This technique provides crucial insights into interfacial segregation and solute behavior, aiding material design.
• The findings contribute to a deeper understanding of strengthening mechanisms and phase stability in cemented carbides.