Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy
The as-cast Al-4.6Mg alloy was subjected to deformation and sensitization–desensitization heat treatment, and then the microstructure and the enhancement mechanism of Sr were investigated by optical microscopy, scanning electron microscopy–energy-dispersive spectroscopy, electron backscatter diffrac...
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MDPI AG
2023-08-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/15/5450 |
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| author | Zhanshou Yang Yaping Dong Wu Li Xin Liu Haitao Feng |
| author_facet | Zhanshou Yang Yaping Dong Wu Li Xin Liu Haitao Feng |
| author_sort | Zhanshou Yang |
| collection | DOAJ |
| description | The as-cast Al-4.6Mg alloy was subjected to deformation and sensitization–desensitization heat treatment, and then the microstructure and the enhancement mechanism of Sr were investigated by optical microscopy, scanning electron microscopy–energy-dispersive spectroscopy, electron backscatter diffraction, and transmission electron microscopy. The precipitation phases of Al-4.6Mg alloy were mainly β-Al<sub>3</sub>Mg<sub>2</sub>, Al<sub>6</sub>Mn, and Al<sub>6</sub>(Mn Cr), and the nanoscale precipitation phases were Al<sub>3</sub>Mn and Al<sub>11</sub>Mn<sub>4</sub>. The formation of β-Al<sub>3</sub>Mg<sub>2</sub> was hindered by the addition of 0.1 wt.% Sr. In addition, the precipitate phase Al<sub>4</sub>Sr and the nano-sized precipitate phase τ-Al<sub>38</sub>Mg<sub>58</sub>Sr<sub>4</sub> were uniformly distributed in the spherical matrix. The addition of Sr promoted the redissolution of Mg atoms in Al-4.6Mg alloy, increasing the solubility of Mg in the α-Al matrix from 4.7 wt.% to 5.1 wt.%. The microstructure analysis showed that Sr addition inhibited the recovery and recrystallization of the alloy because the Sr element elevated the recrystallization temperature. As a result, the grain deformation was intensified, the grain size was decreased from 6.96 μm to 5.39 μm, the low-angle grain boundaries were increased from 78.7 at % to 84.6 at %, and the high-angle grain boundaries were increased from 21.3 at % to 15.4 at %. Furthermore, the mechanical properties of the alloy were significantly improved, and the plasticity degraded after the addition of the Sr element. The yield strength of the alloy was enhanced mainly through fine grain strengthening, dispersion strengthening, solid solution strengthening, and working hardening. The strengthening mechanisms were analyzed in detail. |
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| spelling | doaj.art-2ad7e1086339471c9737bfcd868eee472023-11-18T23:13:28ZengMDPI AGMaterials1996-19442023-08-011615545010.3390/ma16155450Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg AlloyZhanshou Yang0Yaping Dong1Wu Li2Xin Liu3Haitao Feng4Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, ChinaKey Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, ChinaKey Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, ChinaKey Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, ChinaKey Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, ChinaThe as-cast Al-4.6Mg alloy was subjected to deformation and sensitization–desensitization heat treatment, and then the microstructure and the enhancement mechanism of Sr were investigated by optical microscopy, scanning electron microscopy–energy-dispersive spectroscopy, electron backscatter diffraction, and transmission electron microscopy. The precipitation phases of Al-4.6Mg alloy were mainly β-Al<sub>3</sub>Mg<sub>2</sub>, Al<sub>6</sub>Mn, and Al<sub>6</sub>(Mn Cr), and the nanoscale precipitation phases were Al<sub>3</sub>Mn and Al<sub>11</sub>Mn<sub>4</sub>. The formation of β-Al<sub>3</sub>Mg<sub>2</sub> was hindered by the addition of 0.1 wt.% Sr. In addition, the precipitate phase Al<sub>4</sub>Sr and the nano-sized precipitate phase τ-Al<sub>38</sub>Mg<sub>58</sub>Sr<sub>4</sub> were uniformly distributed in the spherical matrix. The addition of Sr promoted the redissolution of Mg atoms in Al-4.6Mg alloy, increasing the solubility of Mg in the α-Al matrix from 4.7 wt.% to 5.1 wt.%. The microstructure analysis showed that Sr addition inhibited the recovery and recrystallization of the alloy because the Sr element elevated the recrystallization temperature. As a result, the grain deformation was intensified, the grain size was decreased from 6.96 μm to 5.39 μm, the low-angle grain boundaries were increased from 78.7 at % to 84.6 at %, and the high-angle grain boundaries were increased from 21.3 at % to 15.4 at %. Furthermore, the mechanical properties of the alloy were significantly improved, and the plasticity degraded after the addition of the Sr element. The yield strength of the alloy was enhanced mainly through fine grain strengthening, dispersion strengthening, solid solution strengthening, and working hardening. The strengthening mechanisms were analyzed in detail.https://www.mdpi.com/1996-1944/16/15/5450Al-4.6Mg alloySrmicrostructuremechanical propertiesstrengthening mechanism |
| spellingShingle | Zhanshou Yang Yaping Dong Wu Li Xin Liu Haitao Feng Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy Materials Al-4.6Mg alloy Sr microstructure mechanical properties strengthening mechanism |
| title | Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy |
| title_full | Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy |
| title_fullStr | Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy |
| title_full_unstemmed | Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy |
| title_short | Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy |
| title_sort | effect of sr on microstructure and strengthening mechanism of al 4 6mg alloy |
| topic | Al-4.6Mg alloy Sr microstructure mechanical properties strengthening mechanism |
| url | https://www.mdpi.com/1996-1944/16/15/5450 |
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