Abstract
Ag nanomaterials have been investigated as a filler material for brazing Inconel 718 well below the bulk melting temperature of Ag using both vacuum and laser brazing. However, Ag nanoparticles and Ag nanowires exhibit different bonding strengths. In this study, we focus on different diffusion and wetting behaviors of two kinds of nanopastes. At 550 °C, the areal coverage of the nanopaste decreases as a result of shrinkage in the nanopaste. The shrinkage is followed by rapid wetting and spreading on the Inconel 718 surface. A deeper investigation to the diffusion behavior of Ag nanoparticle and Ag nanowire pastes during laser brazing provides a clear correlation between the diffusion distance and the bonding strength. The diffusion of the base material into the Ag joint is shown to result in a concentration “hump” near the Ag-Inconel 718 interface of different base material elements which is likely caused by a difference in diffusivity of Ag and the Inconel 718 constituent elements. Ag NW joints were found to have a thicker diffusion zone, but also exhibit some Nb/Mo segregation when brazed using 300-W laser power. This may lead in different metallurgic bonding.
| Original language | English |
|---|---|
| Pages (from-to) | 169-176 |
| Number of pages | 8 |
| Journal | Welding in the World |
| Volume | 62 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2018 |
Funding
Funding information This project is jointly supported by the Institute of Public Service, University of Tennessee, through the I’UCRC project of the National Science Foundation and a seed grant from Oak Ridge National Laboratory, Department of Energy, USA, and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), P. R. China. John Dunlap, Maulik Patel, and the Joint Institute of Advanced Materials permitted use of their electron microscopy facilities and provided the training needed to operate those devices.
Keywords
- Brazing
- Diffusion
- Inconel
- Laser brazing
- Pastes
- Wetted area