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18.97.14.82
18.97.14.82
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가스분무한 Al-8wt.%Fe 합금분말의 급속응고과정에 대한 수치해석
Numerical Analysis on Rapid Solidification of Gas-atomized Al-8wt. pct Fe Droplets
김성균 , 최회진 , 나형용 ( Seong Gyoon Kim , Hoi Jin Choi , Hyung Yong Ra )
UCI I410-ECN-0102-2009-580-008951587

A numerical analysis on the microstructural evolutions of microcellular and cellular α -aluminum phase in the gas-atomized Al-8wt. pct droplets was represented. The 2-dimensional non-Newtonian heat transfer and the dendritic growth theory in the undercooled melt were combined under the assumptions of a point nucleation on droplet surface and the macroscopically smooth solid-liquid interface enveloping the cell tips. It reproduced the main characteristic features of the reported microstructures quite well. It predicted a considerable volume fraction of segregation-free region in a droplet smaller than l0㎛ if an initial undercooling larger than 100K is given. The volume fractions of the microcellular region(g_A) and the sum of the microcellular and cellular region(g_a) were predicted as functions of the heat transfer coefficient, h and initial undercooling, ΔT. It was shown that g_A and g_a, in the typical gas-atomization processes with h=0.1-1.0W/㎠K, are dominated by ΔT and h, respectively, but for h larger than 4.0W/㎠K, a fully microcellular structure can be obtained irrespective of the initial undercooling.

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