Phase Selection and Microstructure Characteristics of Directionally Solidified Gd5Ge4 Alloy by Laser Zone Re-melting

Abstract:

The Gd5Ge4 alloy with the peritectic reaction during solidification was prepared by the arc-melt method under protection of argon atmosphere. The as-cast alloys were cut and directionally solidified with the help of laser rapid solidification technique. Microstructure characteristics and phase selection of Gd5Ge4 during the rapid directional solidification by laser zone re-melting were investigated. The microstructure originating from steady-state growth?was evaluated with the help of optical microscope (OM) and X-ray diffraction (XRD). The alloy after laser zone directional solidification possesses obvious preferred orientation and the amorphization occurs under this condition. The cellular spacing could be expressed as a function of the laser scanning velocity during the rapid solidification. An acceptable combination is found between the experimental results and the classical J-H numerical solidification model for a rapid cellular/dendritic growth.