Interface microstructure regulation of Mg/Ti bimetals by thermal diffusion treatment of Ni-coated TC4 alloy. (August 2022)

• Record Type: Journal Article
• Authors: Zhao, Jianhua; Wen, Fulin; Feng, Kaiqing; Gu, Cheng; Wang, Yajun
• Is Part Of: Intermetallics. Volume 147(2022)
• Publication Date: 2022-08
• Subjects: Bimetallic material -- Solid-liquid compound casting -- Interface -- Intermetallic compound -- AZ91D Mg -- NiTi alloy; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2022.107594
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: In the present work, solid-liquid compound casting process was used to fabricate TC4/AZ91D bimetals using thermal diffused Ni-coated TC4 alloy. The effects of thermal diffusion time of Ni-coated TC4 alloy on interface microstructure evolution and mechanical features of TC4/AZ91D bimetals were investigated. The interface microstructure has undergone the evolution of NiTi2, NiTi and Ni3 Ti to NiTi2, NiTi and Ni2 Ti4 O (Mg) at Ni–Ti interface and (Mg2 Ni + α-Mg) eutectic structure + Ni2 Mg3 Al ternary phase to eutectic-free (only Al3 Ni, Al3 Ti and Ni2 Mg3 Al) at Ni–Mg interface as the thermal diffusion time of Ni-coated TC4 alloy increased from 0.5 h to 5 h and 9 h. The maximum shear strength of 105.2 MPa was obtained for the eutectic-free interface of TC4/AZ91D bimetals when Ni-coated TC4 alloy were thermal diffused by 5 h. The rupture of TC4/AZ91D bimetals mainly takes place at (Mg2 Ni + α-Mg) eutectic structure or between the interface of Ni3 Ti layer/(Mg2 Ni + α-Mg) eutectic structure when the thermal diffusion time of Ni-coated TC4 alloy is 0.5 h. Besides, with the thermal diffusion time increases to 5 and 9 h, the rupture occurs at the NiTi2 and Ni2 Ti4 O (Mg) reaction layers, respectively. Graphical abstract: Image 1 Highlights: A novel surface thermal modified Ni-coated TC4 alloy were used to fabricate TC4/AZ91D bimetals. The intermetallic compounds generated at the interface of TC4/AZ91D bimetals include NiTi2, NiTi, Ni3 Ti and Ni2 Ti4 O (Mg) at Ni–Ti interface and (Mg2 Ni + α-Mg) eutectic structure, Ni2 Mg3 Al, Al3 Ti and Al3 Ni at Ni–Mg interface. TC4/AZ91D bimetals fractured at (Mg2 Ni + α-Mg) eutectic structure or between the interface of Ni3 Ti/(Mg2 Ni + α-Mg) eutectic structure, but NiTi2 and Ni2 Ti4 O (Mg) reaction layers when the thermal diffusion time of Ni-coated TC4 alloy were 0.5 h, 5 h and 9 h.