Sn和Ni对过冷Ag-28.1Cu共晶合金凝固组织的影响

Abstract

In order to reveal the influence and mechanism of Sn and Ni elements with different solid solubility in eutectic phase on the undercooled eutectic solidification structure, Ag-28.1Cu-xM (x=0wt.%, 0.5wt.%, 1wt.%; M=Sn, Ni) eutectic alloys were prepared using a combination of molten glass purification and cyclic superheating method. The effect of the third component Sn and Ni on the solidification structure of undercooled Ag-Cu eutectic alloy was investigated. The results showed that the addition of Sn did not change the macroscopic zoning characteristics of the microscructure. Moreover, an anomalous increase in eutectic and coarsening was observed in the microstructure, with a random orientation distribution. During solidification, Sn formed a concentration gradient perpendicular to the solid-liquid interface, resulting in the instability of the cellular interfaces and the formation of dendrites, but still maintaining coupled eutectic growth. While the addition of Ni eliminated the macroscopic zoning characteristics. In the microstructure, single-phase dendrites were formed, exa single orientation distribution. This is because Ni diffused parallel to the solid-liquid interface, causing the eutectic alloy growth to transit from coupled growth to decoupled growth. © 2024 Harbin Institute of Technology. All rights reserved.