|Title：||Morphologies of intermetallic compound phases in Sn-Cu and Sn-Co peritectic alloys during directional solidification|
|Author：||*Peng Peng1, 2, 3, Jin-mian Yue4, An-qiao Zhang1, Jia-tai Wang3, and Jiang-lei Fan5|
|Address：||1. School of Physics and Electronic Information Engineering, Qinghai Normal University, Xining 753000, China; 2. School of Materials and Energy, Lanzhou University, Lanzhou 730000, China; 3. Northwest Rare Metal Materials Research Institute, Shizuishan 753099, Ningxia, China; 4. Shanxi Taigang Stainless Steel Co., Ltd., Taiyuan 030003, China; 5. School of Mechanical and Electrical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450000, China|
|Key words：||intermetallic compound phase; peritectic alloy; directional solidification; solubility range; sub-structure|
The morphologies of intermetallic phases (IMCs) during directional solidification of the Sn-Cu (L+Cu3Sn→Cu6Sn5) and Sn-Co (L+CoSn→CoSn2) peritectic systems were analyzed. The primary Cu3Sn and peritectic Cu6Sn5 phases in Sn-Cu alloy are IMCs whose solubility ranges are narrow, while both the primary CoSn and peritectic CoSn2 phases in Sn-Co alloy are IMCs whose solubility ranges are nil in equilibrium condition. The experimental results before acid corrosion shows that the dendritic morphology of both the Cu6Sn5 and CoSn2 phases can be observed. The investigation on the local dendritic morphology after deep acid corrosion shows that these dendrites are composed of small sub-structures with faceted feature. Faceted growth of the primary Cu3Sn and CoSn phases is also confirmed, and a faceted to non-faceted transition in their morphologies is observed with increasing growth velocities. Further analysis shows that the dendritic morphology is formed in the solidified phases whose solubility range is larger during peritectic solidification.