Residual stress induced failure of Ti-6Al-4V/Si3N4 joints brazed with Ag-Cu-Ti filler: The effects of brazing zone's elasto-plasticity and ceramics' intrinsic properties. Issue 13 (October 2021)

• Record Type: Journal Article
• Authors: Ong, Fei Shen; Rheingans, Bastian; Goto, Kenta; Tobe, Hirobumi; Ohmura, Takahito; Janczak-Rusch, Jolanta; Sato, Eiichi
• Is Part Of: Journal of the European Ceramic Society. Volume 41:Issue 13(2021)
• Page Start: 6319
• Page End: 6329
• Publication Date: 2021-10
• Subjects: Residual stress -- Ceramics -- Dissimilar brazing -- Finite element analysis (FEA) -- Nano-indentation; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2021.06.038
• Languages: English
• ISSNs: 0955-2219

Abstract

Graphical abstract: Highlights: Brazing of Ti-6Al-6V and polycrystalline Si3 N4 ceramics having different intrinsic properties. Comparative mechanical and microstructural characterizations of the brazed metal/ceramics joints. Quantitative analysis of the local elasto-plastic properties of as-received filler and brazing zone by nano-indentation. Validation of experimental bending strengths by thermo-mechanical finite-element-analysis based on nano-indentation results. Abstract: The residual-stress induced failure of Ti-6Al-4V/Si3 N4 joints brazed with two different Si3 N4 ceramics possessing different intrinsic properties was elucidated through experimental and finite-element (FE) thermo-mechanical simulations incorporating the local elasto-plastic properties of the as-received Ag-Cu-Ti filler and the brazing zone characterized by nano-indentation. All tested joints fractured mainly from the ceramics due to residual stress, and their bending strengths increased when using Si3 N4 ceramics of higher intrinsic strength. FE-analysis based on the as-received filler's properties overestimated the nominal bending strengths by approximately 100 MPa in both joints; nano-indentation revealed that the depletion of ductile Ag-Cu phase and growth of hard Cu-Ti intermetallic compounds reduced the plastically deformable thickness after being brazed, whereby they resulted in higher residual stress in the ceramics. Finally, the validity of FE-estimated bending strengths was enhanced when considering the effective plastically deformable thickness of filler (30 μm) instead of the as-received state (50 μm).