Fabrication And Influence Factors Study Of Mono-sized Fe-based Metallic Glass Spherical Particles

Fe-based metal glass particles have good applications in microfabrication,magnetic powder cores,thermal spray coating,and synthetic bulk metal glass because of their good mechanical properties,soft magnetic properties,and superplasticity in supercooled liquid regions.The Pulsated Orifice Ejection Method?POEM?is a technique for preparing uniform particles based on the principle of ink jet printing.The technology has the advantages of low cost,unlimited raw materials,uniform and controllable particle size,high sphericity,and consistent thermal history.This paper optimized and reformed the high-melting-point POEM equipment based on local pulsated disturbance proposed.The Fe-based Fe₆₀Ni_7.5Mo_7.5P₁₀C₁₀B₅ metal glass particles were prepared under Ar gas and He gas atmosphere respectively,and the effects of process parameters on particle size and dispersion were discussed.The surface topography,internal phase composition and structure,and thermal stability properties of the particles were evaluated,and a theoretical model was established to calculate the critical cooling rate of the metal glass.The main conclusions obtained were:?1?The uniform particle size,high sphericity,good surface quality and no internal defects Fe-based Fe₆₀Ni_7.5Mo_7.5P1₀C₁₀B₅ metal glass particles can be prepared by POEM.?2?Technological parameters have important effects on particles:The diameter of particles increased with the increase of the pressure difference between the crucible and the chamber,the applied voltage and the reduction of t_up time.Within the range of experiment,the optimal parameters applied in preparation of uniform metal glass particles are followed:the pressure difference ranges from 5kPa to 6kPa,the applied voltage is 105V,the t_up time is 250?s.?3?During cooling and solidification,the surface of the metal glass particles contacted with gas first,and the cooling rate is the fastest.Therefore,the metal glass particles prepared under different gas atmospheres exhibit complete glass phase on their surface.?4?In the experimental conditions of this paper,the critical diameter for obtaining fully amorphous phase should be less than 285?m in Ar atmosphere.However,the particle with the maximum diameter of 383?m in He atmosphere also maintain amorphous phase.This is because the thermal conductivity of He gas is much greater than that of Ar gas?5?The critical cooling rate of Fe-based Fe₆₀Ni_7.5Mo_7.5P₁₀C₁₀B₅ metal glass particles calculated by the theoretical model should be over 1300K/s.