Patent ID: 6461403
Filing Date: 2002-10-08
Classification: B22F,C22C

Abstract:
A method of forming particles of substantially uniform size with an induced duplex microstructure in an atomization apparatus comprising the steps of:releasing a stream of molten material through an aperture under positive pressure upward into a cooling chamber; allowing the stream to break up into substantially spherical droplets having a kinetic energy sufficient to follow an upward trajectory above the aperture; and, allowing the droplets to impact a chill body disposed at a predetermined distance from the aperture within a collection area of the cooling chamber, wherein at least one of the positive pressure and the predetermined distance is selected to allow the droplets to cool sufficiently to form a skin that substantially retains the droplet shape during impact at the chill body, and to allow the droplets to remain at least partially molten upon impacting the chill body such that, upon impact, the chill body provides a quenching surface that rapidly cools the at least partially molten droplets and induces a duplex microstructure therein.