TY - JOUR
T1 - Enhanced diffusion bonding of alloy 617 using electric field-assisted sintering
AU - Zhang, Xinchang
AU - McMurtrey, Michael D.
AU - Bass, Ryann E.
AU - Patterson, Tate
AU - Mohale, Ninad
AU - Lillo, Thomas M.
AU - Rufner, Jorgen F.
N1 - Funding Information:
This project was funded by the Idaho National Laboratory Laboratory-Directed Research & Development (LDRD) Program under the Department of Energy (DOE) Idaho Operations Office Contract DE-AC07-05-ID14517 .
Funding Information:
In addition to grain growth, temperature resulted in differences in GB migration across the DB interface. As shown in Figs. 10a and 11a, planar grain boundaries were found at the interface of the EFAS-#1. No GB migration was observed. As the temperature increased to 1100 °C, GB migration was initiated ( Figs. 10c and 11e), although the amount of GB migration was very low. However, EFAS at 1150 °C resulted in excellent GB migration (88.5%) as seen in Fig. 11g, leaving the original interface barely visible. According to Eq. (1), the temperature is the main factor controlling diffusion coefficient. Diffusion improves as the temperature increases. DB temperature should be optimized since bonding at inappropriate high temperatures will fail due to excessive deformation (e.g., HP-#4). However, it should be emphasized that temperature alone does not result in excellent GB migration. This can be evidenced by HP-#4 (53.2%) and EFAS-#8 (88.5%) which have different diffusion qualities while both were made at equivalent temperature conditions. Literature also supports similar findings that limited GB migration was achieved using HP even at 1250 °C [11]. It is due to the precipitates at the interface of the HP samples which inhibited GB migration. It also needs to be noted that temperature is important for DB using EFAS. This is because EFAS at inappropriate temperatures (1050 °C and 1100 °C) failed to achieve good diffusion (Fig. 10a–c). This suggests that the electric current results in a temperature profile that plays a key role in the DB of Alloy 617.This project was funded by the Idaho National Laboratory Laboratory-Directed Research & Development (LDRD) Program under the Department of Energy (DOE) Idaho Operations Office Contract DE-AC07-05-ID14517.
Publisher Copyright:
© 2023 The Author(s)
PY - 2023/9/19
Y1 - 2023/9/19
N2 - The development of compact heat exchangers (CHXs) has gained increasing interest in many industries owing to their high thermal efficiency and reduced size. Diffusion bonding (DB) is an advantageous technique for fabricating CHXs. Alloy 617 is a candidate for manufacturing CHXs for high-temperature advanced nuclear reactors due to its elevated-temperature properties. Previous endeavors in DB of Alloy 617 were conducted by hot pressing (HP), which reported precipitates at the diffusion-bond interface, limited grain boundary (GB) migration, and significantly reduced high-temperature mechanical properties. To overcome these challenges, this study investigated DB of Alloy 617 using electric field-assisted sintering (EFAS). Stacks composed of three sheets were bonded with EFAS using different temperatures, pressures, and hold times. DB using HP as the zero-current analog of EFAS was also performed for comparison. The result shows that Cr- and Mo-rich precipitates were formed at the interface of the hot-pressed samples. The electric current and temperature in EFAS play a significant role in precipitation and GB migration. The electric current coupled with correct temperatures can effectively prevent precipitate formation at the interface and achieve excellent GB migration. Nanoscale Al-rich oxide was formed at the interface of the samples made by both HP and EFAS, but grain boundaries can ignore the nanoscale Al-oxide and migrate across the interface. The temperature, pressure, and hold time also affected diffusion. The temperature is a prerequisite for a successful GB migration, and GB migration can be enhanced by increasing pressure and hold time.
AB - The development of compact heat exchangers (CHXs) has gained increasing interest in many industries owing to their high thermal efficiency and reduced size. Diffusion bonding (DB) is an advantageous technique for fabricating CHXs. Alloy 617 is a candidate for manufacturing CHXs for high-temperature advanced nuclear reactors due to its elevated-temperature properties. Previous endeavors in DB of Alloy 617 were conducted by hot pressing (HP), which reported precipitates at the diffusion-bond interface, limited grain boundary (GB) migration, and significantly reduced high-temperature mechanical properties. To overcome these challenges, this study investigated DB of Alloy 617 using electric field-assisted sintering (EFAS). Stacks composed of three sheets were bonded with EFAS using different temperatures, pressures, and hold times. DB using HP as the zero-current analog of EFAS was also performed for comparison. The result shows that Cr- and Mo-rich precipitates were formed at the interface of the hot-pressed samples. The electric current and temperature in EFAS play a significant role in precipitation and GB migration. The electric current coupled with correct temperatures can effectively prevent precipitate formation at the interface and achieve excellent GB migration. Nanoscale Al-rich oxide was formed at the interface of the samples made by both HP and EFAS, but grain boundaries can ignore the nanoscale Al-oxide and migrate across the interface. The temperature, pressure, and hold time also affected diffusion. The temperature is a prerequisite for a successful GB migration, and GB migration can be enhanced by increasing pressure and hold time.
KW - Alloy 617
KW - Compact heat exchangers
KW - Diffusion bonding
KW - Electric-field-assisted sintering
KW - Hot pressing
UR - https://www.scopus.com/pages/publications/85173104323
UR - https://www.mendeley.com/catalogue/4e3afe4e-cf98-3e17-b63c-62c906955b67/
U2 - 10.1016/j.jmrt.2023.09.080
DO - 10.1016/j.jmrt.2023.09.080
M3 - Article
AN - SCOPUS:85173104323
SN - 2238-7854
VL - 26
SP - 7033
EP - 7051
JO - Journal of Materials Research and Technology
JF - Journal of Materials Research and Technology
ER -