| Title |
Microstructure and the Plane to Cell transition of Unidirectionally solidified Al - Zn and Al - Cu - Zn Alloys |
| Authors |
맹선재(Sun Chae Maeng); 신명철(Myung Chul Shin) |
| Abstract |
The transition from plane to cellular interface in dilute solid solution of aluminium containing zinc and copper+zinc has been studied by means of unidirectional solidification. The solid solution. alloys of different initial solute concentration (C_0) have been solidified under the different ratio of temperature gradient (G) to rate of solidification (R), and the cell morphology has been observed. The plane to cell transition has been plotted on a graph of C_0 vs G/R, and the critical transition condition can be described by a straight line in the graph as anticipated by the Tiller`s equation on supercooling. Applying the Tiller`s equation to the experimental result, liquid diffusion coefficient of zinc in aluminium has been estimated to be 1.8×10^(-5) ㎠/sec. The result of aluminium-copper-zinc ternary alloy indicates that there exists an interaction between the copper and zinc atoms, in such a way to decrease the equilibrium distribution coefficient of zinc in aluminium by the addition of copper. |