Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy
The precipitation of intermetallic phases and the associated hardening by artificial aging treatments at elevated temperatures above 400 °C were systematically investigated in the commercially available AC2B alloy with a nominal composition of Al–6Si–3Cu (mass%). The natural age hardening of the art...
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| author | Ruoqi Li Naoki Takata Asuka Suzuki Makoto Kobashi Yuji Okada Yuichi Furukawa |
| author_facet | Ruoqi Li Naoki Takata Asuka Suzuki Makoto Kobashi Yuji Okada Yuichi Furukawa |
| author_sort | Ruoqi Li |
| collection | DOAJ |
| description | The precipitation of intermetallic phases and the associated hardening by artificial aging treatments at elevated temperatures above 400 °C were systematically investigated in the commercially available AC2B alloy with a nominal composition of Al–6Si–3Cu (mass%). The natural age hardening of the artificially aged samples at various temperatures was also examined. A slight increase in hardness (approximately 5 HV) of the AC2B alloy was observed at an elevated temperature of 480 °C. The hardness change is attributed to the precipitation of metastable phases associated with the α-Al<sub>15</sub>(Fe, Mn)<sub>3</sub>Si<sub>2</sub> phase containing a large amount of impurity elements (Fe and Mn). At a lower temperature of 400 °C, a slight artificial-age hardening appeared. Subsequently, the hardness decreased moderately. This phenomenon was attributed to the precipitation of stable θ-Al<sub>2</sub>Cu and Q-Al<sub>4</sub>Cu<sub>2</sub>Mg<sub>8</sub>Si<sub>6</sub> phases and their coarsening after a long duration. The precipitation sequence was rationalized by thermodynamic calculations for the Al–Si–Cu–Fe–Mn–Mg system. The natural age-hardening behavior significantly varied depending on the prior artificial aging temperatures ranging from 400 °C to 500 °C. The natural age-hardening was found to strongly depend on the solute contents of Cu and Si in the Al matrix. This study provides fundamental insights into controlling the strength level of commercial Al–Si–Cu cast alloys with impurity elements using the cooling process after solution treatment at elevated temperatures above 400 °C. |
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| issn | 1996-1944 |
| language | English |
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| publishDate | 2021-11-01 |
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| spelling | doaj.art-1c704ff121eb4a9595b58a0fbbbfe4c72023-11-23T02:39:06ZengMDPI AGMaterials1996-19442021-11-011423715510.3390/ma14237155Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu AlloyRuoqi Li0Naoki Takata1Asuka Suzuki2Makoto Kobashi3Yuji Okada4Yuichi Furukawa5Department of Materials Process Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, JapanDepartment of Materials Process Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, JapanDepartment of Materials Process Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, JapanDepartment of Materials Process Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, JapanToyota Motor Corporation, Toyota-cho, Toyota 471-8571, JapanToyota Motor Corporation, Toyota-cho, Toyota 471-8571, JapanThe precipitation of intermetallic phases and the associated hardening by artificial aging treatments at elevated temperatures above 400 °C were systematically investigated in the commercially available AC2B alloy with a nominal composition of Al–6Si–3Cu (mass%). The natural age hardening of the artificially aged samples at various temperatures was also examined. A slight increase in hardness (approximately 5 HV) of the AC2B alloy was observed at an elevated temperature of 480 °C. The hardness change is attributed to the precipitation of metastable phases associated with the α-Al<sub>15</sub>(Fe, Mn)<sub>3</sub>Si<sub>2</sub> phase containing a large amount of impurity elements (Fe and Mn). At a lower temperature of 400 °C, a slight artificial-age hardening appeared. Subsequently, the hardness decreased moderately. This phenomenon was attributed to the precipitation of stable θ-Al<sub>2</sub>Cu and Q-Al<sub>4</sub>Cu<sub>2</sub>Mg<sub>8</sub>Si<sub>6</sub> phases and their coarsening after a long duration. The precipitation sequence was rationalized by thermodynamic calculations for the Al–Si–Cu–Fe–Mn–Mg system. The natural age-hardening behavior significantly varied depending on the prior artificial aging temperatures ranging from 400 °C to 500 °C. The natural age-hardening was found to strongly depend on the solute contents of Cu and Si in the Al matrix. This study provides fundamental insights into controlling the strength level of commercial Al–Si–Cu cast alloys with impurity elements using the cooling process after solution treatment at elevated temperatures above 400 °C.https://www.mdpi.com/1996-1944/14/23/7155Al–Si–Cu alloyage-hardeningintermetallic phasesartificial agingnatural aging |
| spellingShingle | Ruoqi Li Naoki Takata Asuka Suzuki Makoto Kobashi Yuji Okada Yuichi Furukawa Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy Materials Al–Si–Cu alloy age-hardening intermetallic phases artificial aging natural aging |
| title | Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy |
| title_full | Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy |
| title_fullStr | Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy |
| title_full_unstemmed | Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy |
| title_short | Precipitation Hardening at Elevated Temperatures above 400 °C and Subsequent Natural Age Hardening of Commercial Al–Si–Cu Alloy |
| title_sort | precipitation hardening at elevated temperatures above 400 °c and subsequent natural age hardening of commercial al si cu alloy |
| topic | Al–Si–Cu alloy age-hardening intermetallic phases artificial aging natural aging |
| url | https://www.mdpi.com/1996-1944/14/23/7155 |
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