Abstract
The microstructure and mechanical properties of two die-cast hypoeutectic Al-Ce-based alloys modified with Sc, Zr and Er micro-additions – Al-1.5Ce-0.14Sc-0.03Zr with high Sc content and Al-1.4Ce-0.02Sc-0.06Zr-0.003Er (at%) with low Sc content – are studied, with focus on the two strengthening phases: micron-scale Al11Ce3 platelets formed on solidification and L12 Al3(Sc,Zr,Er) nanoprecipitates formed during aging. The evolution of microstructure and microhardness upon isothermal aging at 350 and 400 °C, and the creep resistance at 300 °C, are studied and compared to alloys containing only one of these strengthening phases. The Al11Ce3 and L12 phases form mostly independently of each other, except in the low-Sc alloy where scavenging of Er and Si by Al11Ce3 on solidification reduces the kinetics of precipitation and number density of the L12 precipitates formed on subsequent aging. The two strengthening phases, while mostly independent of each other chemically, interact synergistically in terms of strengthening. At ambient temperature, the hardness of the Al11Ce3- and L12-strengthened alloys is higher than that of similar alloys containing only one strengthening phase. At 300 °C, the creep strain rate is reduced by as much as five orders of magnitude in the Al11Ce3- and L12-strengthened alloys compared to alloys containing only L12 precipitates. This improvement in both room and elevated-temperature mechanical properties is modeled through a combination of load transfer from the Al11Ce3 micro-platelets, and precipitation strengthening from the Al3(Sc,Zr,Er) nanoprecipitates.
| Original language | English |
|---|---|
| Article number | 118354 |
| Journal | Acta Materialia |
| Volume | 240 |
| DOIs | |
| State | Published - Nov 2022 |
| Externally published | Yes |
Funding
This work made use of the Materials Characterization and Imaging, which has received support from the MRSEC program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. This work made use of the EPIC facility of the NUANCE Center, which has received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, SHyNE Resource (NSF ECCS-2025633), the International Institute for Nanotechnology, IIN (NIH-210OD026871), and the State of Illinois, through the INN. Atom-probe tomography was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph at NUCAPT was purchased and upgraded with grants from the NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781, N00014-1712870) programs. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at NU. The authors also thank Dr. Amir Farkoosh (Northwestern University) for his assistance with creep testing and APT data analysis. CNE was supported by the DEVCOM Army Research Laboratory (ARL) Research Associateship Program (RAP). This research received funding from the DEVCOM Army Research Laboratory under Cooperative Agreement numbers W911NF-20-2-0292 and W911NF-21-2-02199. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of the Army Research Laboratory or the US Government. The US Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. This work made use of the Materials Characterization and Imaging, which has received support from the MRSEC program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. This work made use of the EPIC facility of the NUANCE Center, which has received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, SHyNE Resource (NSF ECCS-2025633), the International Institute for Nanotechnology, IIN (NIH-210OD026871), and the State of Illinois, through the INN. Atom-probe tomography was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph at NUCAPT was purchased and upgraded with grants from the NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781, N00014-1712870) programs. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at NU. The authors also thank Dr. Amir Farkoosh (Northwestern University) for his assistance with creep testing and APT data analysis. CNE was supported by the DEVCOM Army Research Laboratory (ARL) Research Associateship Program (RAP). This research received funding from the DEVCOM Army Research Laboratory under Cooperative Agreement numbers W911NF-20-2-0292 and W911NF-21-2-02199. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of the Army Research Laboratory or the US Government. The US Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein.
Keywords
- Al-Ce alloys
- Aluminum alloys
- Creep
- Eutectic
- L1