Ni–Cu droplets were processed by electromagnetic levitation, in a drop-tube and by atomization. The droplet diameters varied from 30 μm to 7 mm, and the entire composition range was studied. Most microstructures observed were coarse-dendritic or refined-equiaxed. Microstructure-selection maps have been constructed for the drop-tube and atomization techniques showing the predominant microstructure as a function of composition and droplet size. From the results on levitated droplets, a selection map has been constructed which relates the microstructure to the composition and the melt undercooling reached prior to nucleation. The results are analysed within a recently developed model for grain refinement which is based upon the fragmentation of primary dendrites. The influence of impurities on the microstructure formation in material of commercial purity is investigated.
Application of microstructure selection maps to droplet solidification: a case study of the Ni-Cu system
ZAMBON, ANDREA;RAMOUS, EMILIO;
1998
Abstract
Ni–Cu droplets were processed by electromagnetic levitation, in a drop-tube and by atomization. The droplet diameters varied from 30 μm to 7 mm, and the entire composition range was studied. Most microstructures observed were coarse-dendritic or refined-equiaxed. Microstructure-selection maps have been constructed for the drop-tube and atomization techniques showing the predominant microstructure as a function of composition and droplet size. From the results on levitated droplets, a selection map has been constructed which relates the microstructure to the composition and the melt undercooling reached prior to nucleation. The results are analysed within a recently developed model for grain refinement which is based upon the fragmentation of primary dendrites. The influence of impurities on the microstructure formation in material of commercial purity is investigated.
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