先进材料疑固实验室 Laboratory of Advanced Materials Solidification 1896 1920 1987 2006 Solidification of single phase alloys(2) Dr.Mingxu Xia anced Maw 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
1896 1920 1987 2006 Solidification of single phase alloys (2) Dr. Mingxu Xia
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 Interface instability of pure metal Solidification microstructure:Cells and dendrites nced Mav 上浒充通大学 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 • Interface instability of pure metal • Solidification microstructure: Cells and dendrites
先进材料疑固实验室 Situation 3:No diffusion in the solid,normal Laboratory of Advanced Materials Solidification diffusion in the liquid,no convection. In Situation 3,there exists a steady state in which the solid growth does not cause any change of the distribution of solute concentration in the liguid. y af IS S anced Materia 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
In Situation 3, there exists a steady state in which the solid growth does not cause any change of the distribution of solute concentration in the liquid. Situation 3: No diffusion in the solid, normal diffusion in the liquid, no convection
先进材料疑固实验室 Situation 3:No diffusion in the solid,Limited diffusion in the liquid,no convection. Laboratory of Advanced Materials Solidification L Phase diagram T厂 C Initial point koCp C's Co C'L Colko 5 Solute concentration (b) L L Clk C Transient stage Steady state stage 5 (c) 5 (d) The figure is from 切聊过被阶段 稳定生长阶段 徐洲,姚寿山主编,《材料 8 mitial Steady 加工原理》科技出版社, transient state 最后过该阶段1 2003 stage. stage Final p62 8 transientL (e) stage 熟 上浒充通大 SHANGHAI JIAO TONG UNIVERSITY
Situation 3: No diffusion in the solid, Limited diffusion in the liquid, no convection
先进材料凝固实验室 Situation 3:No diffusion in the solid,normal diffusion in the liquid,no convection. Laboratory of Advanced Materials Solidification aCL at S L △x R is growth rate. rr+Ar Initial transient→ Steady-State→ Terminal Transient Boundary Terminal transient layer Initial transient start X dist ance finish 上游充通大学 SHANGHAI JIAO TONG UNIVERSITY
R is growth rate. Situation 3: No diffusion in the solid, normal diffusion in the liquid, no convection