# First-Principles Calculation and Experimental Study on Interface Stability, Electronic Characteristics, and Mechanical Properties of WC-Co-Y Cemented Carbide

## TL;DR

This study shows that adding yttrium improves the strength, hardness, and wear resistance of a type of carbide material.

## Contribution

The integration of first-principles calculations and experiments reveals how Y doping optimizes WC-Co interfaces for enhanced mechanical properties.

## Key findings

- Y doping reduces WC/Co interfacial energy and strengthens bonding through Y-W orbital hybridization.
- 0.5 wt.% Y improves hardness to 1454 HV and toughness to 9.84 MPa·m1/2 while reducing wear rates.
- Y addition refines grains and uniformly distributes the Co binder phase, enhancing overall performance.

## Abstract

What are the main findings?
Y doping reduces WC/Co interfacial energy and enhances bonding strength. Y-W orbital hybridization forms strong covalent bonds at the atomic interface.Material achieves dual improvement: Hardness (1454 HV) and toughness (9.84 MPa·m1/2).Optimal 0.5 wt.% Y refines grains and uniformly distributes the Co binder phase. Wear resistance is significantly improved, with the lowest wear rate at 0.5 wt.% Y.

Y doping reduces WC/Co interfacial energy and enhances bonding strength. Y-W orbital hybridization forms strong covalent bonds at the atomic interface.

Material achieves dual improvement: Hardness (1454 HV) and toughness (9.84 MPa·m1/2).

Optimal 0.5 wt.% Y refines grains and uniformly distributes the Co binder phase. Wear resistance is significantly improved, with the lowest wear rate at 0.5 wt.% Y.

What are the implications of the main findings?
Provides an atomic-scale mechanism for rare earth-enhanced cemented carbides and offers a design strategy for co-optimizing hardness and toughness in composites;Validates the integration of first-principles calculations with experimental validation;Identifies an optimal Y doping threshold for superior comprehensive properties.

Provides an atomic-scale mechanism for rare earth-enhanced cemented carbides and offers a design strategy for co-optimizing hardness and toughness in composites;

Validates the integration of first-principles calculations with experimental validation;

Identifies an optimal Y doping threshold for superior comprehensive properties.

This study aims to clarify the optimization mechanism of yttrium (Y) doping on the interfacial bonding and macroscopic properties of WC/Co cemented carbides, with the goal of achieving materials that combine high hardness, high toughness, and excellent wear resistance through interfacial regulation. Combining first-principles calculations and experimental verification, the interfacial energy, density of states, and charge density of WC/Co and WC/CoY interfaces were systematically investigated. Three alloys (WC-10Co, WC-10Co-0.5Y, and WC-10Co-1Y) were prepared, and the effects of Y addition were quantitatively evaluated through microstructural characterization, mechanical testing, and tribological experiments. The calculation results indicate that Y doping reduces interfacial energy, enhances interfacial bonding, and increases surface energy, which contributes to improved toughness. At the atomic scale, the orbital hybridization between Y and W promotes the formation of strong covalent bonds at the interface, thereby enhancing interfacial bonding strength. The experimental results show that the introduction of Y significantly improves the overall performance of the material, with the alloy containing 0.5 wt.% Y exhibiting the best performance. Its Vickers hardness reaches (1454 ± 1.3) HV, fracture toughness is (9.84 ± 0.15) MPa·m1/2, and the wear rate is as low as 0.794 × 10−5 mm3·N−1·m−1.