上海交通大学：《材料加工原理 Principles of Materials Processing》教学资源（课件讲稿）凝固和铸造 Solidification and casting_Solidification of single phase alloys（3）

先进材料疑固实验室 路 Laboratory of Advanced Materials Solidification 1896 1920 1987 2006 Solidification of single phase alloys(3) Dr.Mingxu Xia anced Mate 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY

1896 1920 1987 2006 Solidification of single phase alloys (3) Dr. Mingxu Xia

先进材料疑固实验室 References Laboratory of Advanced Materials Solidification M.C.Flemings,凝固过程 W.Kurz,凝固原理 介万奇，凝固技术 JA Dantzig and M Rappaz,Solidification r of pavanced 上降充通大学 SHANGHAI JIAO TONG UNIVERSITY

References M.C.Flemings, 凝固过程 W.Kurz,凝固原理 介万奇，凝固技术 JA Dantzig and M Rappaz, Solidification

先进材料疑固实验室 OUTLINE Laboratory of Advanced Materials Solidification Solute Redistribution Solute distribution coefficient Solute redistribution in equilibrium state Solute redistribution in non-equilibrium state Solute distribution in front of S/L interface Application:Zone melting Morphology Instability of a S/L interface Constitutional undercooling Morphological instability of a S/L interface Solidification microstructure:Cells and dendrites ·Constrained growth Preferred growth direction ·Dendrite arm spacing Formation of equiaxed grains 。Cast microstructure 上降充通大学 SHANGHAI JIAO TONG UNIVERSITY

OUTLINE Solute Redistribution • Solute distribution coefficient • Solute redistribution in equilibrium state • Solute redistribution in non-equilibrium state • Solute distribution in front of S/L interface • Application: Zone melting Morphology Instability of a S/L interface • Constitutional undercooling • Morphological instability of a S/L interface • Solidification microstructure: Cells and dendrites • Constrained growth • Preferred growth direction • Dendrite arm spacing • Formation of equiaxed grains • Cast microstructure

先进材料疑固实验室 General observation Laboratory of Advanced Materials Solidification Ig.8.8 Microstructures observed in an SCN-0.66 wt%Salol alloy,directionally olidified with G=4.5 K mm-1.The pulling speed from left to right,is 0.57,2.0, 7,and 7.6 um s-1.(Reproduced with permission from ref.[31].) anced Mat 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY

General observation

先进材料疑固实验室 General observation Laboratory of Advanced Materials Solidification Fig.8.9 A time series from the directional solidification of a succinonitrile-acetone alloy.The initial condition is a solid at rest in a temperature gradient,giving the planar interface in the left-hand panel.Solidification occurs by pulling the alloy at constant speed vp to the left,as indicated.(Reproduced with permission from W.Losert.) 上游充通大学 SHANGHAI JIAO TONG UNIVERSITY

General observation