Strength optimization of two-step-bonded Ti-6Al-4V/Si3N4 joint with Nb interlayer via transient-liquid-phase bonding and active-metal brazing. Issue 6 (June 2022)

• Record Type: Journal Article
• Authors: Ong, Fei Shen; Nishi, Ryotaro; Tobe, Hirobumi; Sato, Eiichi
• Is Part Of: Journal of the European Ceramic Society. Volume 42:Issue 6(2022)
• Page Start: 2707
• Page End: 2717
• Publication Date: 2022-06
• Subjects: Brazing -- Transient-liquid-phase bonding -- Ceramics -- Residual stress -- Finite element analysis; 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.2022.01.039
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: A novel two-step bonding of Ti-6Al-4V/Si3 N4 joint was developed with Nb interlayer as residual-stress reliever via low-pressure transient-liquid-phase bonding (TLPB) of Ti-6Al-4V/Nb side prior to active-metal brazing of Nb/Si3 N4 side. While 1.75 mass% of Ti in a 50-µm-thick CUSIL-ABA® filler was sufficient for sound bonding at Nb/Si3 N4 side when brazed at 1103 K for 10 min, one-step-brazed joints with bonding area of 10 × 10 mm 2 were prone to failure at the Ti-6Al-4V/Nb side due to brittle Cu-Ti intermetallic compounds (IMCs). Replacing brazing of Ti-6Al-4V/Nb side with TLPB using pure Cu and Ni foils as filler at 1213 K for 180 min eliminated the formation of brittle IMCs via homogenization of (α + β)-Ti; bending strength increased to 193 MPa with residual-stress-induced failure from Si3 N4 ceramics. Finally, effectiveness of stress-accommodation via Nb interlayer and filler's plastic flow was quantitatively verified with reasonable fidelity by finite-element analysis incorporating temperature-dependent elasto-plastic properties. Graphical Abstract: ga1 Highlights: Robust two-step dissimilar bonding via transient-liquid-phase bonding and brazing. Optimization of filler's Ti content and brazing temperature for sound Si3 N4 brazing. Low-pressure transient-liquid-phase bonding of Ti-6Al-4V to Nb by Cu and Ni fillers. Estimation of joint strength via finite-element-analyzed thermal residual stress.