The effect of particle size on densification and mechanical properties of Fe-based bulk metallic glasses by spark plasma sintering

The effect of particle size on the densification and mechanical properties of Fe-based bulk metallic glasses prepared by spark plasma sintering is still not clearly understood. In this work, high-density Fe-based bulk metallic glasses were prepared by spark plasma sintering. Effect of particle size on densification and mechanical properties was investigated. The results show that densification is improved with decreasing particle size. The highest relative density and maximum instantaneous densification rate are 99.21% and 6.59 × 10⁻³, respectively. Powders with particle size of 29.51 µm after sintering were completely transformed from spherical to polyhedral. The numerous mechanically interlocked structures are observed at contact area, which significantly improves powder interfacial bond strength. Correspondingly, microhardness and wear resistance are improved. The highest microhardness, lowest friction coefficient, wear depth, wear volume and wear rate are 1576.4 HV, 0.63, 2.55 µm, 5.58 mm³ and 3.10 × 10⁻⁶ mm³ N⁻¹ m⁻¹. In addition, influence of particle size on Joule heating effect, atomic diffusion and sintering drive forces was analyzed by theoretical calculation. Higher current and larger sintering driving forces are generated between smaller powders during sintering. The total contact area between powders increases with decreasing particle size, and high contact area promotes atomic diffusion. The results indicate that high-density Fe-based BMGs are easily prepared by small powders.