Influence of Cu content on microstructure, mechanical, and tribological properties of Fe-Cu alloy matrices prepared by hot-pressed sintering

The demand for cost-effective and efficient machining solutions has stimulated the development of cobalt-free metallic matrices for diamond tools. In this work, Fe-Cu alloy (FCA) matrices with different Cu contents (18 wt% (FCA18), 20 wt% (FCA20), and 30 wt% (FCA30)) were fabricated by hot-pressed sintering to identify the optimal Cu content that balances performance and cost. The effects of Cu content on the microstructure, mechanical properties, tribological behavior, and corrosion resistance were systematically evaluated. The results show that increasing Cu content enhances densification, and a maximum relative density of 99.19 % is achieved for FCA30. FCA20 exhibits the highest hardness (174.82 ± 5.79 HV 0.2 ) and tensile strength (471.02 ± 23.51 MPa), which are attributed to the combined effects of solid-solution strengthening, grain refinement, and homogeneous dispersion of Cu-rich phases. However, FCA20 shows the most severe wear, with an average friction coefficient of 0.764 and a wear scar depth of 294.97 μm, due to dominant abrasive and adhesive wear mechanisms. In contrast, FCA30 displays superior wear resistance, with the lowest friction coefficient of 0.365 and a wear scar depth of 115.48 μm, resulting from the formation of a protective lubricating film. Electrochemical measurements in 3.5 wt% NaCl solution revealed that FCA20 has the best corrosion resistance, with the most noble corrosion potential (−0.60 V) and the lowest corrosion current density (9.53 ×10 −6 A·cm −2 ), owing to its refined microstructure and reduced micro-galvanic effects. Overall, a Cu content of 20 wt% is identified as the optimal composition for Fe-Cu matrices in diamond tools, providing a cost-effective balance between mechanical strength and corrosion resistance, albeit at the expense of wear resistance.