Rapid solidification experiments including laser remelting, melt-spinning and wedge casting, were carried out to investigate the rapid solidification behavior of Zn-rich Zn-Ag peritectic alloys containing up to 9.0 at percent Ag. For comparison, Bridgman solidification experiments of the same alloys were also carried out for growth velocities ranging from 0.02 to 4.82 mm/s. which were lower than that of 12-54.5 mm/s for laser remelting and that in the order of 10~2 mm/s for melt-spun samples. Optical images and transmission electron microscopy (TEM) showed that instead of the typical structure consisting of primary dendrites of euro surrounded by peritectic #eta#, a two-phase plate-like #eta#+euro with (or without) primary dendrites of euro was observed in Zn-3.1, 4.4, 6.3 and 9.0 at percent Ag alloys when the growth velocity was higher than a critical value. It was found that the higher was the alloy concentration, the higher was the critical growth velocity for the formation of fully two-phase plate-like #eta#+euro . From the TEM micrographs, the volume fraction of euro in the fully two-phase plate-like #eta#+euro increased from 0.09 to 0.50 with increase in alloy concentration from 3.1 to 6.3 at percent Ag. A plausible analysis was proposed to interpret the dependence of microstructural transitions on the growth velocity in Zn-3.1 to 9.0 at percent Ag alloys, that is. primary dendrites of euro in a matrix of peritectic #eta#->two-phase plate-like #eta#+euro with primary dendrites of euro -> fully two-phase plate-like #eta#+euro.
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