Phase separation behavior of mono-sized Al-70%Sn coreshell particles fabricated by pulsated orifice ejection method

Abstract

Al-70%Sn (mass fraction) core-shell structure particles with small size distribution, high sphericity and consistent external morphology were successfully prepared by pulsated orifice ejection method(POEM). The effects of particle size, superheat degree and gas atmosphere on the internal morphology were investigated. The formation mechanism of core-shell structure particle with an Al-rich core and a Sn-rich shell was discussed by electron probe micro-analyzer, energy dispersive spectroscopy analysis and cooling rate simulation. The results show that with the increase of particle size, the internal morphology of particles changes from non-core-shell structure to core-shell structure of liquid globule aggregated towards the core type, regular core-shell type and the core deviated from the center type. The true core volume fraction of regular core-shell structure particles was calculated by the section correction method. It was found that within the region of liquid phase separation initiated, the true core volume fraction of regular core-shell structure particles increase with the increase of the undercooling degree. This method can be used to estimate the undercooling degree at which liquid phase separation initiated of regular core-shell structure particles.

Keywords

• al-sn alloy
• pulsated orifice ejection method
• core-shell structure
• mono-sized particle
• undercooling degree