The Effect of Rapid Solidification Velocity on the Microstructure of Ag-Cu Alloys

Phase-field investigation on the non-equilibrium interface dynamics of rapid alloy solidification

“…The light band is segregation free and has uniform composition, so that it has been presumed that the planar growth results in these light bands. lished [66]. The band structure was observed with the velocities between those for cell/dendrites and for microsegregation-free structures.…”

“…This microstructure is characterized by the alternating structures of dendritic/eutectic and planar growth, and has been observed in many alloy solidifications [66].…”

“…In the result of this analysis, it was shown that at high velocities there exists oscillatory instability Figure 2.28 Experimentally determined microstructure selection map for Ag-Cu alloys by electron beam solidification [66] for relatively long wavelength perturbations, in addition to the instability predicted by MullinsSekerka's theory. This modified stability analysis suggested that the instability may occur with so called "solute pump mechanism."…”

“…Dendritic alloys: Ag-1˜65% Cu [66,67,68,69,70,71], Al-20˜33%Cu [72], Al-0.5˜4%Fe [73], Al-20%Pd [65], Al-6%Zr [74] Eutectic alloys: Ag-28%Cu [66], Al-33%Cu [75,76] Formation of this banded structure occurs at velocities near the limit of the absolute stability: the absolute stability velocity can be calculated from Mullins-Sekerka's stability analysis of planar front and the velocity, a perturbation with any wavelength tends to diminish, i.e. a planar front is the most stable.…”

Reminiscences About a Chemistry Nobel Prize Won with Metallurgy: Comments on D. Shechtman and I. A. Blech; Metall. Trans. A, 1985, vol. 16A, pp. 1005–12

“…Before Shechtman returned to Israel in the fall of 1983, he completed another important rapid solidification work. [8] Although no explanation was necessary to refute both the universal periodicity of crystals and that only periodic objects can give sharp diffraction patterns, Shechtman apparently felt a need for an explanation of his finding. The observation lay dormant for 2 years.…”