Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed
The AZ series of Mg alloys have become promising in several industrial fields thanks to its potential microstructure refinement and the β-Mg<sub>17</sub>Al<sub>12</sub> eutectic that controls the mechanical behaviour. Simultaneously, the rapid degradation characterizing Mg al...
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MDPI AG
2023-10-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/20/6620 |
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| author | Emanuele Ghio Emanuela Cerri |
| author_facet | Emanuele Ghio Emanuela Cerri |
| author_sort | Emanuele Ghio |
| collection | DOAJ |
| description | The AZ series of Mg alloys have become promising in several industrial fields thanks to its potential microstructure refinement and the β-Mg<sub>17</sub>Al<sub>12</sub> eutectic that controls the mechanical behaviour. Simultaneously, the rapid degradation characterizing Mg alloys makes the investigation of their corrosion behaviour necessary. The present work considers high-pressure die cast (HPDC) AZ91 alloy to evaluate its corrosion behaviour in 1M NaCl solution and investigates how different friction stir process parameters can affect the corrosion responses. No studies analyse the effects induced by the friction stir processed zone, reached using high rotational speeds (>2000 rpm), on the unprocessed HPDC AZ91 alloy. In addition, the morphological analysis of the corroded surfaces having a friction stir processed zone, in which the grain refinement was not obtained, is not present in the literature yet. Microstructural features were investigated by optical microscope and X-ray diffraction analysis before and after the friction stir process. These were subsequently correlated to the corrosion responses after the immersion tests. The results show that HPDC samples with a very smooth surface have the best corrosion resistance with a corrosion rate lower than 3 mm/year, evaluated through the weight loss, compared to the rougher ones. Both the amount of β-Mg<sub>17</sub>Al<sub>12</sub> eutectic and the wt.% Al in the α-Mg matrix, as well as the surface roughness, influence the corrosion behaviour of friction stir processed samples. The best corrosion resistance was obtained with an HPDC alloy processed at 2500 rpm and 50 mm/min. |
| first_indexed | 2024-03-10T21:05:40Z |
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| id | doaj.art-4d8014e35c5e47e980e0e0126d3a029b |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T21:05:40Z |
| publishDate | 2023-10-01 |
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| spelling | doaj.art-4d8014e35c5e47e980e0e0126d3a029b2023-11-19T17:09:52ZengMDPI AGMaterials1996-19442023-10-011620662010.3390/ma16206620Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational SpeedEmanuele Ghio0Emanuela Cerri1Department of Engineering and Architecture, University of Parma, Via G. Usberti, 181/A, 43124 Parma, ItalyDepartment of Engineering and Architecture, University of Parma, Via G. Usberti, 181/A, 43124 Parma, ItalyThe AZ series of Mg alloys have become promising in several industrial fields thanks to its potential microstructure refinement and the β-Mg<sub>17</sub>Al<sub>12</sub> eutectic that controls the mechanical behaviour. Simultaneously, the rapid degradation characterizing Mg alloys makes the investigation of their corrosion behaviour necessary. The present work considers high-pressure die cast (HPDC) AZ91 alloy to evaluate its corrosion behaviour in 1M NaCl solution and investigates how different friction stir process parameters can affect the corrosion responses. No studies analyse the effects induced by the friction stir processed zone, reached using high rotational speeds (>2000 rpm), on the unprocessed HPDC AZ91 alloy. In addition, the morphological analysis of the corroded surfaces having a friction stir processed zone, in which the grain refinement was not obtained, is not present in the literature yet. Microstructural features were investigated by optical microscope and X-ray diffraction analysis before and after the friction stir process. These were subsequently correlated to the corrosion responses after the immersion tests. The results show that HPDC samples with a very smooth surface have the best corrosion resistance with a corrosion rate lower than 3 mm/year, evaluated through the weight loss, compared to the rougher ones. Both the amount of β-Mg<sub>17</sub>Al<sub>12</sub> eutectic and the wt.% Al in the α-Mg matrix, as well as the surface roughness, influence the corrosion behaviour of friction stir processed samples. The best corrosion resistance was obtained with an HPDC alloy processed at 2500 rpm and 50 mm/min.https://www.mdpi.com/1996-1944/16/20/6620AZ91 alloypitting corrosionfriction stir processcorrosion resistancesurface roughnessmicro-galvanic corrosion |
| spellingShingle | Emanuele Ghio Emanuela Cerri Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed Materials AZ91 alloy pitting corrosion friction stir process corrosion resistance surface roughness micro-galvanic corrosion |
| title | Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed |
| title_full | Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed |
| title_fullStr | Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed |
| title_full_unstemmed | Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed |
| title_short | Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed |
| title_sort | corrosion behaviour of high pressure die cast az91 alloy in nacl solution effects of friction stir process at high rotational speed |
| topic | AZ91 alloy pitting corrosion friction stir process corrosion resistance surface roughness micro-galvanic corrosion |
| url | https://www.mdpi.com/1996-1944/16/20/6620 |
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