科研之友
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摘要
Experimental work is described in undercoolings and microstructures of Pb-Sn eutectic alloy droplets emulsified in oil bath. By controlling experimental variables, the final droplet size produced was in the range of 10 to 300mum, and measured undercoolings ranged up to about 70K. Microstructures of the droplets depend strongly on the degree of undercooling before solidification. By increasing undercooling, three major microstructure transitions, which include the morphological changes of eutectic phase from lamellar to anomalous in lower undercooling level and of primary alpha-Pb phase from dendrite to equiaxed grains in higher undercooling levels, are observed. The phase change from eutectic to primary alpha-Pb dendrite plus eutectic is also observed. The physical mechanism of these microstructure transitions is analyzed on the basis of the Lipton-Kurz-Trivedi theory for dendrite growth and the Jackson-Hunt theory for lamellar eutectic growth.
- 出版日期2004-10
