Laser resolidification of Zn-rich Zn-Ag peritectic alloys

Abstract

Laser remelting experiments were performed by a 1.0 kW continuous CO2 laser for investigating the rapid solidification behavior of Zn-rich Zn-Ag peritectic alloys. Three kinds of microstructures occurs with the varying of laser scanning speed and Ag content in the alloys. It is mainly plate-like single-phase cellular η when the Ag content was lower than 1.8% (mole fraction). As the Ag content increased, instead of typical structure of primary dendrites of ε surrounded by peritectic η, a two-phase plate-like η+ε with primary dendrites of ε is found when the laser scanning speed was higher than a critical value. Intercellular spacing of cellular ε or interphase spacing of two-phase couple growth η+ε decreases with increasing laser scanning speed.