Rheology-informed criteria for tailoring size and morphology in amorphous alloy atomization

초록

Amorphous alloys exhibit exceptional mechanical properties, yet their intrinsic brittleness and size limitations hinder widespread application. Additive manufacturing offers a promising route to overcome these challenges, but gas atomization of highly viscous multicomponent glass-forming alloys often yields non-spherical morphologies, including microscale wires, elliptical particles with tails, and dumbbell-shaped forms, which are rarely observed in conventional crystalline alloys, that compromise feedstock quality. Herein, we identify key thermal and rheological conditions governing size and morphology evolution during high-pressure atomization using Zr46Cu37.63Ag8.36Al8 and Zr46Cu30.14Ag8.36Al8Be7.5. Acknowledging that melt temperature and atomization geometries cannot fully account for morphology changes across glass-forming alloys with varying viscosity, we highlight the need for a generalizable, rheology-based framework for atomization. Specifically, by integrating rheological data of molten alloys measured using the electrostatic levitation technique with statistical analysis of particle/wire size and morphology, we reveal an exponential relationship between the median (powder/wire) diameter (D0.5) and the normalized liquidus temperature (Tl/TInj), and construct the Weber (We) - Ohnesorge (Oh) profile to describe the dynamics of secondary breakup. Consequently, we introduce a dimensionless parameter Ω=OhWe incorporating aerodynamics (We) and rheological effects (Oh) and demonstrate that spherical particle formation is favored when Ω < 0.07 and Tl/TInj < 0.7. This work paves the way for producing high-quality amorphous alloy feedstocks for additive manufacturing and guiding the tailored fabrication of amorphous alloy components in a broad composition range of glass-forming alloy systems.

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