Characteristics of 7055Al alloy powders manufactured by gas-solid two-phase atomization: A comparison with gas atomization process

In this paper, the principle of gas-solid two-phase atomization methodology for metal powder is demonstrated. A cost-effective production technology for high-quality metal powder was proposed. The morphology, size distribution, microstructure and cooling rate of two-phase atomized 7055Al powder were examined. The experimental results have demonstrated a number of advantages and unique features of gas-solid two-phase atomization in the preparation of metal powders. When the Argon gas pressure P = 0.6 MPa and iron particle feed rate M′ = 235.6 g·min^− 1, the mass median diameter (d₅₀) of the 7055Al powder manufactured by two-phase atomization process was 22.8 μm, which is reduced by 52.7% compared with gas atomized powders with d₅₀ = 48.2 μm under the same atomization parameters. Experimental results also showed that the gas-solid two-phase atomized powders exhibited more irregular shapes than gas atomized powders. The cooling rate of most powders was in the range of 10⁴– 10⁵ K/s, and for some extra checked fine powders the cooling rate can even reach 10⁶ K/s. The two-phase atomized powders had larger cooling rate and presented obvious rapid solidification characteristics than gas atomized powder with the same diameter. Moreover, this study indicates that gas-solid two-phase atomization could be a promising high-quality and low-cost metal powder preparation technology.