Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition
We address here an important issue related to sensitization effects in Al5083 by mitigating the grain boundary precipitation of the beta phase and demonstrate that the addition of a small amount of boron to Al5083 impedes the precipitation of the beta phase, Al<sub>3</sub>Mg<sub>2&...
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MDPI AG
2023-06-01
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| Series: | Corrosion and Materials Degradation |
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| Online Access: | https://www.mdpi.com/2624-5558/4/2/16 |
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| author | Ramasis Goswami Alex Moser Ronald L. Holtz Syed B. Qadri Andrew Geltmacher |
| author_facet | Ramasis Goswami Alex Moser Ronald L. Holtz Syed B. Qadri Andrew Geltmacher |
| author_sort | Ramasis Goswami |
| collection | DOAJ |
| description | We address here an important issue related to sensitization effects in Al5083 by mitigating the grain boundary precipitation of the beta phase and demonstrate that the addition of a small amount of boron to Al5083 impedes the precipitation of the beta phase, Al<sub>3</sub>Mg<sub>2</sub>, also known as the Samson phase. In Al–Mg alloys, the precipitation of Al<sub>3</sub>Mg<sub>2</sub> usually occurs at grain boundaries in the temperature range of 50 to 200 °C from a supersaturated solid solution of Al–Mg and makes these alloys susceptible to intergranular corrosion and stress corrosion cracking. Upon boron addition, we show, using transmission electron microscopy, that a diboride phase, AlMgB<sub>2</sub>, forms at grain boundaries instead of the beta phase upon extended annealing at 150 °C. This diboride phase does not dissolve in saltwater, suggesting it is less anodic relative to the matrix. To quantify and compare the dissolution characteristics, we carried out nitric acid mass loss test for Al5083 samples containing 3 wt.% boron treated at 190 h at 150 °C, and fully sensitized Al5083 samples containing 0.0 wt.% boron. We estimate the mass loss to be 4 mg/cm<sup>2</sup> for boron containing samples as compared to the mass loss of 45 mg/cm<sup>2</sup> for samples without boron, indicating that the addition of boron is highly effective in suppressing the susceptibility to intergranular corrosion in Al5000 series alloys. This provides a potential route to minimize the longstanding problem of ship structure sensitization. |
| first_indexed | 2024-03-11T02:36:57Z |
| format | Article |
| id | doaj.art-872c5dc854ed4979a076108ca12b865e |
| institution | Directory Open Access Journal |
| issn | 2624-5558 |
| language | English |
| last_indexed | 2024-03-11T02:36:57Z |
| publishDate | 2023-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Corrosion and Materials Degradation |
| spelling | doaj.art-872c5dc854ed4979a076108ca12b865e2023-11-18T09:53:16ZengMDPI AGCorrosion and Materials Degradation2624-55582023-06-014231733010.3390/cmd4020016Complete Desensitization of Aluminum–Magnesium Alloys via Boron AdditionRamasis Goswami0Alex Moser1Ronald L. Holtz2Syed B. Qadri3Andrew Geltmacher4Materials Science and Technology Division, Naval Research Laboratory (NRL), Washington, DC 20375, USAMaterials Science and Technology Division, Naval Research Laboratory (NRL), Washington, DC 20375, USAMaterials Science and Technology Division, Naval Research Laboratory (NRL), Washington, DC 20375, USAMaterials Science and Technology Division, Naval Research Laboratory (NRL), Washington, DC 20375, USAMaterials Science and Technology Division, Naval Research Laboratory (NRL), Washington, DC 20375, USAWe address here an important issue related to sensitization effects in Al5083 by mitigating the grain boundary precipitation of the beta phase and demonstrate that the addition of a small amount of boron to Al5083 impedes the precipitation of the beta phase, Al<sub>3</sub>Mg<sub>2</sub>, also known as the Samson phase. In Al–Mg alloys, the precipitation of Al<sub>3</sub>Mg<sub>2</sub> usually occurs at grain boundaries in the temperature range of 50 to 200 °C from a supersaturated solid solution of Al–Mg and makes these alloys susceptible to intergranular corrosion and stress corrosion cracking. Upon boron addition, we show, using transmission electron microscopy, that a diboride phase, AlMgB<sub>2</sub>, forms at grain boundaries instead of the beta phase upon extended annealing at 150 °C. This diboride phase does not dissolve in saltwater, suggesting it is less anodic relative to the matrix. To quantify and compare the dissolution characteristics, we carried out nitric acid mass loss test for Al5083 samples containing 3 wt.% boron treated at 190 h at 150 °C, and fully sensitized Al5083 samples containing 0.0 wt.% boron. We estimate the mass loss to be 4 mg/cm<sup>2</sup> for boron containing samples as compared to the mass loss of 45 mg/cm<sup>2</sup> for samples without boron, indicating that the addition of boron is highly effective in suppressing the susceptibility to intergranular corrosion in Al5000 series alloys. This provides a potential route to minimize the longstanding problem of ship structure sensitization.https://www.mdpi.com/2624-5558/4/2/16Al–Mg alloysAl5083Al5456sensitizationprecipitationmicrostructure |
| spellingShingle | Ramasis Goswami Alex Moser Ronald L. Holtz Syed B. Qadri Andrew Geltmacher Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition Corrosion and Materials Degradation Al–Mg alloys Al5083 Al5456 sensitization precipitation microstructure |
| title | Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition |
| title_full | Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition |
| title_fullStr | Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition |
| title_full_unstemmed | Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition |
| title_short | Complete Desensitization of Aluminum–Magnesium Alloys via Boron Addition |
| title_sort | complete desensitization of aluminum magnesium alloys via boron addition |
| topic | Al–Mg alloys Al5083 Al5456 sensitization precipitation microstructure |
| url | https://www.mdpi.com/2624-5558/4/2/16 |
| work_keys_str_mv | AT ramasisgoswami completedesensitizationofaluminummagnesiumalloysviaboronaddition AT alexmoser completedesensitizationofaluminummagnesiumalloysviaboronaddition AT ronaldlholtz completedesensitizationofaluminummagnesiumalloysviaboronaddition AT syedbqadri completedesensitizationofaluminummagnesiumalloysviaboronaddition AT andrewgeltmacher completedesensitizationofaluminummagnesiumalloysviaboronaddition |