銅および銅合金の過冷融液におけるデンドライト成長形態について
1977 年 41 巻 8 号 p. 761-766
詳細
1977 年 41 巻 8 号 p. 761-766
The structures of copper, Cu-10 wt%Ni alloy and Cu-8 wt%Sn alloy solidified from the supercooled melts have been investigated. The growth morphology of a dendrite and the coarsening of dendrite arms have been discussed, and the following results are obtained.
(1) At small or intermediate supercooling, the shape of a dendrite is a cone which consists of a primary stem, secondary stems and ternary stems. At large supercooling, thin dendrites grow isotropically from the nucleation point.
(2) The grain refinement by small supercooling is due to the remelting of dendrites, and the coarse grains formed by intermediate supercooling consist of a dendrite element. At large supercooling, the isotropic growth of thin dendrites causes the grain refinement.
(3) The coarsening of dendrite arms occurs mainly on the ternary or quaternary stems near the grain boundary, and the dendrite arm spacing is nearly proportional to the 1/3 power of the local solidification time as in the case of the unidirectional solidification.
