On the Prospects of Using Nanoindentation and Wear Test to Study the Mechanical Behavior of Fe-Based Metallic Glass Coating Reinforced by B₄C Nanoparticles

In this study, Fe-based metallic glass was served as the matrix in which various ratios of hard B₄C nanoparticles as reinforcing agents were prepared using a high-energy mechanical milling. The feedstock nanocomposite powders were transferred to the coatings using a high-velocity oxygen fuel process. The results showed that the microstructure of the nanocomposite coating was divided into two regions, namely a full amorphous phase region and homogeneous dispersion of B₄C nanoparticles with a scale of 10 to 50 nm in a residual amorphous matrix. As the B₄C content is increased, the hardness of the composite coatings is increased too, but the fracture toughness begins to be decreased at the B₄C content higher than 20 vol pct. The optimal mechanical properties are obtained with 15 vol pct B₄C due to the suitable content and uniform distribution of nanoparticles. The addition of 15 vol pct B₄C to the Fe-based metallic glass matrix reduced the friction coefficient from 0.49 to 0.28. The average specific wear rate of the nanocomposite coating (0.48 × 10⁻⁵ mm³ Nm⁻¹) was much less than that for the single-phase amorphous coating (1.23 × 10⁻⁵ mm³Nm⁻¹). Consequently, the changes in wear resistance between both coatings were attributed to the changes in the brittle to ductile transition by adding B₄C reinforcing nanoparticles.