先进材料疑固实验室 Morphology control of crystals Laboratory of Advanced Materials Solidification Undercooling variation with different temperature gradient With positive temperature gradient Interface dT >0 dT/dx>0,with the crystal growth, dx x1,T↓，Tt Undercooling SIL x Positive temperature gradient Interface With negative temperature gradient dT/dx<0,with the crystal growth, 如 +∠0 xt,△Tt,Tl。 SjL Undercooling ed Ma 2 Negative temperature gradient 上浒充通大 SHANGHAI JIAO TONG UNIVERSITY
Morphology control of crystals Undercooling variation with different temperature gradient Negative temperature gradient Positive temperature gradient With positive temperature gradient dT/dx>0, with the crystal growth, x,ΔT, T With negative temperature gradient dT/dx<0, with the crystal growth, x，ΔT， T
先进材料疑固实验室 Morphology control of crystals Laboratory of Advanced Materials Solidification Positive gradient Interface 70 dx >Latent heat is extracted from solid part. Undercooling >Moving of S/L interface (growth) manipulated by the heat conducting of solid. For substance with sharp interface Interface growth (facted morphololgy):crystal grows Growth of crystal through ledges extension.With x 1, Interface mnd AT,l,and grows as facted morphology with regular shape. 熟 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
Morphology control of crystals Positive gradient Latent heat is extracted from solid part. Moving of S/L interface (growth) manipulated by the heat conducting of solid. Interface growth Interface For substance with sharp interface (facted morphololgy)：crystal grows through ledges extension. With x , △Tk , υ，and grows as facted morphology with regular shape
先进材料疑固实验室 Morphology control of crystals Laboratory of Advanced Materials Solidification Positive gradient Interface 1lm 70 dx For substance with rough interface(non- facted morphololgy):crystal grows as Undercooling continuous growth.With x t,△Tk↓，vl,the humps on the interface will turned into flat. Solid Liquid Solid Liquid heat 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
Morphology control of crystals Positive gradient For substance with rough interface (nonfacted morphololgy)：crystal grows as continuous growth. With x , △Tk , υ，the humps on the interface will turned into flat