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 UNIVERSITYMorphology 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