Understanding the formation of (Al,Si)3Sc and V-phase (AlSc2Si2) in Al-Si-Sc alloys via ex situ heat treatments and in situ transmission electron microscopy studies

Dumbre, Jayshri; Kairy, S.K.; Anber, Elaf A.; Langan, Timothy; Taheri, Mitra L.; Dorin, Thomas; Birbilis, Nick

doi:10.1016/j.jallcom.2020.158511

Cited by 24 publications

(6 citation statements)

References 47 publications

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“…This ternary compound AlSc 2 Si 2 is formed if the alloy contains more than 0.078% Sc and 0.18% Si (in this work, elemental contents are given in wt.% unless otherwise specified). The aforementioned phase has a detrimental effect on the strengthening because it decreases the contents of Sc and Si in the α-Al solid solution, thus lowering the volume fraction of desirable L1 2 -Al 3 X dispersoids [23].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Scandium on the Microstructure of the Aluminium Alloy AA 6086

et al. 2022

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The investigation studied the effects of 0.2 wt.% and 1 wt.% scandium (Sc) additions on the microstructure of the aluminium alloy AA 6086 in different conditions. The alloys were produced by casting into a metallic mould, followed by various heat treatments. The alloys were examined using light microscopy, scanning and transmission electron microscopy, microchemical analysis, differential scanning calorimetry and X-ray diffraction. The phase compositions and solidification sequences were modelled using the CALPHAD approach, which reasonably agreed with the experimental results. The addition of Sc to AA 6086 strongly reduced the grain size of the Al-rich solid solution and induced the appearance of Sc-rich phases AlSc2Si2 and L12-Al3X. Other phases identified in the Sc-free alloy were also found in the Sc-modified alloys. Homogenisation caused the dissolution of most phases and the formation of different types of dispersoids. In the alloy with 0.2% Sc, the distribution of dispersoids was not uniform. The plate-like AlMnCrSi dispersoids formed mainly at the dendrite centres, together with spherical L12 precipitates, while smaller α-AlMnSi and tetragonal t-Al3Zr dispersoids were created elsewhere. The addition of 0.2% Sc did not considerably affect the strengthening of AA 6086. The precipitation during isothermal ageing was slightly delayed and shifted to higher temperatures during continuous heating.

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Section: Introductionmentioning

confidence: 99%

The Effect of Scandium on the Microstructure of the Aluminium Alloy AA 6086

et al. 2022

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“…The dispersoids provided a strong Zener pinning effect during MDF [56][57][58][59] and hot deformation inhibiting the static and dynamic grain growth. It should be noted that the Si atoms can also dissolve in the Al 3 (Sc,Zr) phase, increasing its thermal stability due to the formation of an (Al,Si) 3 (Sc,Zr) phase [60,61]. In the present study, dispersoids exhibited a size of ~10 nm after a second high temperature homogenization step that can be a result of partial Al substitution by Si atoms, which increase the thermal stability of dispersoids.…”

Section: Discussionmentioning

confidence: 51%

Microstructure Evolution and Constitutive Modelling of Deformation Behavior for Al-Mg-Si-Cu-Sc-Zr Alloy Processed with Isothermal Multidirectional Forging

Mochugovskiy,

Kaplanskaya,

Mosleh

et al. 2023

Applied Sciences

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This research is devoted to the microstructure evolution and deformation behavior of the Al-1.2Mg-0.7Si-1.0Cu-0.1Sc-0.2Zr alloy during the isothermal multidirectional forging (MDF) in a large cumulative strain and temperature range. The structure investigation of the studied alloy revealed several phases precipitated during solidification, among which θ(Al2Cu), Q(Al5Cu2Mg8Si6), Mg2Si, Sc-bearing W(AlScCu) and V(AlSi2Sc2) phases were observed. The MDF at 150–350 °C and a maximum cumulative strain of 14.4 significantly refined grain structure providing a mean grain size of 1.2–2.1 µm. The L12 structured Al3(Sc,Zr) dispersoids with a mean size of 10 ± 1 nm were formed during two-step homogenization annealing. Due to Zener pinning of the nanoscale dispersoids and fine-grained structure, the alloy exhibited near-superplastic behavior in a temperature range of 460–500 °C and strain rate range of 2 × 10−3–1 × 10−2 s−1 with the maximum elongation to failure of ~300%. After a strengthening heat treatment, the forged alloy exhibited the yield strength of 326 ± 5 MPa, ultimate tensile strength of 366 ± 5 MPa, and elongation of 10 ± 3%. The hot deformation behavior was described using the Arrhenius type model. The developed model demonstrated high predictability accuracy with a maximum average absolute relative error of 6.6%.

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“…We also suggest that Si atoms partially substitute Al in L1 2 phase providing a more complex dispersoids of (Al,Si) 3 (Sc,Zr) phase as it was demonstrated in Refs. [71,72]. The zone axis [111] of the dispersoids agglomeration was parallel to the corresponding zone axis of the Al matrix that suggested coherency/semi-coherency for the dispersoids and Al matrix.…”

Section: Discussionmentioning

confidence: 99%

A High-Strain-Rate Superplasticity of the Al-Mg-Si-Zr-Sc Alloy with Ni Addition

et al. 2021

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The current study analyzed the effect of Ni content on the microstructure and superplastic deformation behavior of the Al-Mg-Si-Cu-based alloy doped with small additions of Sc and Zr. The superplasticity was observed in the studied alloys due to a bimodal particle size distribution. The coarse particles of eutectic origin Al3Ni and Mg2Si phases with a total volume fraction of 4.0–8.0% and a mean size of 1.4–1.6 µm provided the particles with a stimulated nucleation effect. The L12– structured nanoscale dispersoids of Sc- and Zr-bearing phase inhibited recrystallization and grain growth due to a strong Zener pinning effect. The positive effect of Ni on the superplasticity was revealed and confirmed by a high-temperature tensile test in a wide strain rate and temperature limits. In the alloy with 4 wt.% Ni, the elongation-to-failure of 350–520% was observed at 460 °C, in a strain rate range of 2 × 10−3–5 × 10−2 s−1.

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Understanding the formation of (Al,Si)3Sc and V-phase (AlSc2Si2) in Al-Si-Sc alloys via ex situ heat treatments and in situ transmission electron microscopy studies

Cited by 24 publications

References 47 publications

The Effect of Scandium on the Microstructure of the Aluminium Alloy AA 6086

The Effect of Scandium on the Microstructure of the Aluminium Alloy AA 6086

Microstructure Evolution and Constitutive Modelling of Deformation Behavior for Al-Mg-Si-Cu-Sc-Zr Alloy Processed with Isothermal Multidirectional Forging

A High-Strain-Rate Superplasticity of the Al-Mg-Si-Zr-Sc Alloy with Ni Addition

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