Bin Li and Harold D. Brody
Department of Metallurgy and Materials Engineering
University of
Connecticut
Abstract:
Microradiography has been applied to
observe in real time dendrite growth and coarsening in Sn-13%Bi alloy. A
combination of high intensity synchrotron radiation, real time X-ray
imaging system and high resolving power negative film has been used to
image growing dendrites during solidification. The images obtained in
120-150 micrometer thick samples reveal the evolution of dendrite
morphology and allow quantitative measurement of dendrite growth and
coarsening kinetics.
Dendrite coarsening by remelting from the tips toward the roots during continuous cooling, and dendrite coalescence during isothermal holding were observed in real time. Sporadic dendrite fragmentation was also captured during directional solidification. Temperature gradient zone melting (TGZM) during directional solidification was also observed. A significant amount of remelting was seen on cold sides of dendrite arms, whereas precipitation on hot sides of dendrite arms during continuous cooling and isothermal holding.
2008 Run
Nov 19th - Dec 22nd
