Effects of Zn Interlayer on Microstructures and Mechanical Properties of TC4/AZ91D Bimetal via Solid–Liquid Compound Casting Process

• Published in: International journal of metalcasting 2022, Vol.16 (1), p.419-434
• Main Authors: Shangguan, Jingjing, Zhao, Jianhua, Shi, Yu, Gu, Cheng, Jin, Bingyan, Cheng, Jin, Guo, Yu
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Metallic Materials; Structural Materials; Technical Paper
• ISSN: 1939-5981; 2163-3193
• DOI: 10.1007/s40962-021-00612-9

The solid–liquid compound casting (SLCC) was used to produce Ti/Mg bimetal via hot dip Zn coating, and the interfacial microstructures and mechanical properties of the Mg/Ti bimetal were investigated in this work. The scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) reveal that there is no interlayer metallurgical reaction when the pouring temperature is 670 °C. As the pouring temperature increases to 710 and 750 °C, the thickness of the metallurgical interfacial zone is about 130 and 310 µm, respectively. The interfacial zone is mainly consists of α -Mg and τ -TiAlZn coexistence phases. Thermodynamic models are established to explain the evolution mechanism of α -Mg and τ -TiAlZn coexistence phases. It is concluded that the formation process of α -Mg and τ -TiAlZn phase coexist is as follows: TiZn 5 (s)-to-TiZn 5 (l), and then α -Mg and τ -TiAlZn phases coexist. While the sequence of the phases that formed in the Ti–Al–Zn ternary system is TiAl 3 → τ -TiAlZn, this is based on the fact that the Al atoms are used up at the interfacial zone. The highest shear strength of Zn-coated TC4/AZ91D bimetallic material is up to 34.24 Mpa when the pouring temperature is 710 °C.