The Fabrication of High Strength 7XXX Aluminum Alloy Powders by Centrifugal Disc Atomization

원심분무법에 의한 고강도 7XXX 알루미늄 합금 분말의 제조

7XXX aluminum alloy powders produced by the self-manufactured rotating disc atomizer were investigated to determine the influence of the atomization parameters on the particle size distributions in air atmosphere. The particle size distributions are almost always bimodal with the dominant mode on the large particle size. Average powder size of 7XXX aluminum alloy is $74/{\mu}m~125/{\mu}m$ when melt is poured with the rate of 9g /sec at 730$^{\circ}C$ on a rotating disc of 30㎜ diameter at 6300rad/sec. The mass of finer particle increased when disc diameter, angular velocity, pouring temperature increased and pouring rate decreased. The powder shapes of bimodal change from acicular to tear-drop and from tear-drop to ligament with increasing powder size. Powder shape was determined by the atomization mechanism and oxidation in liquid state. Microstructure of powders appeared to be cell and cellular dendrite. The SDAS of Al-7.9wt%Zn-2.4wt%Mg-1.5wt%Cu-0.9wt%Ni Powders is $0.8{\mu}m~1.0{\mu}m$ for the powders of $size＋44{\mu}m~53{\mu}m$ and $1.6{\mu}m∼1.8{\mu}m$ for the powders of $size＋105{\mu}m~125{\mu}m$, repectively.