Investigation of Al-Si-Cu-Zn-Y-Base Alloy Powders Prepared by Ultrasonic Gas Atomization for Brazing of an Al-Base Alloy

Abstract

The Al-Si-Cu-Zn-Y-base alloys with different Cu and Zn contents were prepared, and their brazing powders were fabricated by ultrasonic gas atomization. Their microstructure evolution, thermal properties, and brazing behavior were investigated, and the results demonstrated that an increase in a Cu content of the alloy promoted the eutectic structure coarsening and the bulk Si phase formation, while an increase in a Zn content could refine this structure. The alloy powders prepared by ultrasonic atomization exhibited ultrafine microstructure, which was little influenced by the alloying composition. The powders had a high weight ratio within 70-150 mm, and an increase in Cu and Zn contents would extend the tendency, especially the Cu content. Its increase raised the solidus and endothermic peak temperatures, while an increase in the Zn content brought about a decrease of those characteristics. The wettability of the alloy powder could be improved by an increase in the Cu and Zn contents. The brazing joint by the alloy powders had the highest shear strength, which could be attributed to its good wettability, relative low solidus and liquidus temperatures.