Open AccessRapid dendritic growth in an undercooled Ni-Cu alloy under the microgravity condition
Author(s) -
Yao Wen-Jing,
Young-Soo Chun,
Xiaohui Han,
Min Chen,
B. Wei,
Guo Zhang
Publication year - 2003
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.52.448
Subject(s) - supercooling , nucleation , materials science , equiaxed crystals , alloy , diffusion , drop (telecommunication) , thermodynamics , dendrite (mathematics) , growth rate , recalescence , eutectic system , metallurgy , telecommunications , physics , geometry , mathematics , computer science
Droplets of Ni-50%Cu alloy with different sizes are rapidly solidified under the condition of microgravity and containerless state within a 3m drop tube. With the increase of undercooling, the microstructural evolution has shown a transition from coarse dendrites to equiaxed grains. The maximum cooling rate of 8×103K/s and the undercooling up to 218K(014TL) are obtained in experiment. Based on a theoretic analysis, the heterogeneous nucleation occurs preferably in Ni-50%Cu droplets. The nucleation rate exceeds 1012 m-3s-1. The rapid dendritic growth of Ni-50%Cu alloy proceeds from the solutal-diffusion-controlled to the thermal-diffusion-controlled growth with the enhancement of undercooling. Under the undercooling of 68K, the segregation degree of liquid at the growing interface reaches a maximum value.