Complex alloy powders produced by different atomization techniques: relationship between heat flow and structure

Abstract

Pre-alloyed powders of Managing 300, IN-100, and MAR-M-509 alloys made by different atomization techniques are compared with respect to chemistry, size, morphology and microstructure. Depending on the process employed and on the size and morphology of the powders produced, measured oxygen contents and secondary dendrite arm spacings vary from 40 ppm to 2000 ppm and 2 to 12μm, respectively. For the Maraging 300 alloy the relationshipd=39.8ε ^−0.30 between secondary dendrite arm spacing,d, and local average cooling rate,ε, is established. A simple heat flow analysis is presented which permits calculation of heat-transfer coefficients and solidification times of powders using this relationship. For example, a heat-transfer coefficienth=3.9 × 10⁻³ cal cm⁻² sec⁻¹ ° C⁻¹ is calculated during solidification of steam atomized coarse powders of Maraging 300 alloy.