Characterisation of worn WC tool using STEM-EDS aided by principal component analysis

Area of Science:

• Materials Science
• Tribology
• Surface Engineering

Background:

• Tool wear in metal machining is driven by interdiffusion and chemical reactions.
• Understanding these wear mechanisms is crucial for designing more resilient materials.
• Complex interactions involving multiple elements and phases complicate wear analysis.

Purpose of the Study:

• To characterize the interaction layer between a titanium alloy and a cemented carbide tool during machining.
• To investigate the role of diffusion processes and chemical reactions in tool wear.
• To evaluate the effectiveness of scanning transmission electron microscopy and energy dispersive X-ray spectroscopy for analyzing wear mechanisms.

Main Methods:

• Utilized scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS).
• Employed principal component analysis (PCA) for chemical correlation and phase signal separation.
• Evaluated X-ray count statistics using simulated spectrum images and theoretical calculations prior to experimentation.

Main Results:

• No intermediate phases were detected between the original tungsten carbide (WC) and the metallic tungsten (W) interaction layer.
• Observed enrichment of minor constituents in the titanium alloy near the tool interface.
• Identified alterations in the solubility of out-diffusing species due to alloy composition changes.

Conclusions:

• STEM-EDS with PCA is effective for characterizing complex tool-workpiece interaction layers.
• Minor constituents in titanium alloys significantly influence diffusion processes during machining.
• Findings provide insights for developing wear-resistant materials and optimizing machining processes.