先进材料疑固实验室 Laboratory of Advanced Materials Solidification 1896 1920 1987 2006 Solidification of single phase alloys(3) Dr.Mingxu Xia anced Mat 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.Kuz,凝固原理 介万奇，凝固技术 JA Dantzig and M Rappaz,Solidification ory of anced Materials Solid 上浒充通大学 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 • 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 Dendrite arm spacing Laboratory of Advanced Materials Solidification Dendrite morphology in usual casting and ingot making processes remains largely unchanged over wide range of cooling rates.It simply becomes finer as heat is extracted at greater rate. PRIMARY PRIMARY ARMS ARMS (a) FIGURE 5-13 Schematic diagram of dendrite structure in Al-4.5%Cu alloy at (a)50 percent solid and (b)90 percent solid.(From Singh et al.) 熟 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
Dendrite arm spacing Dendrite morphology in usual casting and ingot making processes remains largely unchanged over wide range of cooling rates. It simply becomes finer as heat is extracted at greater rate
先进材料疑固实验室 Dendrite arm spacing Laboratory of Advanced Materials Solidification A convenient and widely used measure of the effects of solidification conditions on dendrite structure is dendrite arm spacing,i.e.,the spacing between primary,secondary,or higher- order branches. 生尘 (a) (b) FIGURE 5-14 Formation of new primary arms by branching from secondaries. 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITY
Dendrite arm spacing A convenient and widely used measure of the effects of solidification conditions on dendrite structure is dendrite arm spacing, i.e., the spacing between primary, secondary, or higherorder branches