Enhanced mechanical properties and thermal cycling stability of Al2O3-4J42 joints brazed using Ag–Cu–Ti/Cu/Ag–Cu composite filler. Issue 21 (1st November 2021)

• Record Type: Journal Article
• Authors: Zhu, Qianying; Li, Shenhou; Hu, Kangjia; Liang, Xuewei; Cai, Yangyang; Liu, Zheng; Zhang, Yong
• Is Part Of: Ceramics international. Volume 47:Issue 21(2021)
• Page Start: 30247
• Page End: 30255
• Publication Date: 2021-11-01
• Subjects: Al2O3 ceramic -- Brazing -- Thermal cycling -- Microstructure -- Mechanical properties; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.07.204
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: This study investigates the mechanical properties and microstructure evolution of Al2 O3 -4J42 joints brazed using Ag–Cu–Ti (ACT) and Ag–Cu–Ti/Cu/Ag–Cu (ACTCA) fillers during thermal cycling from 0 °C to 500 °C. The reaction products between Al2 O3 and brazing filler of these two types of joints are mostly composed of Ti–O compounds, Ti4 Cu2 O and Al-based compounds. Brittle intermetallic compounds (IMCs) are observed in ACT joints, but not found in ACTCA joints. The reaction layer in ACT joints becomes thinner and discontinuous with thermal cycles, while that in the ACTCA joints hardly changes. Besides, the stress-induced cracks occur within the Al2 O3 ceramic near the Al2 O3 /filler interface in the ACT joints, but no crack is found in the ACTCA joints. The mechanical tests show that the ACTCA joints maintain at least 217%, 154% and 144% higher shear strength than the ACT joints at 0, 10 and 20 thermal cycles, respectively. The Cu interlayer with low yield strength releases stress through plastic deformation, meanwhile acts as a barrier to prevent elements diffusion and the formation of the brittle IMCs, thus improving the mechanical properties and thermal cycling stability of the joints.