Modification of eutectic Si and the microstructure in an Al-7Si alloy with barium addition

Rao, Jinsong; Zhang, Jin; Liu, Ruxue; Zheng, Jiang; Yin, Dongdi

doi:10.1016/j.msea.2018.05.010

Cited by 50 publications

(8 citation statements)

References 23 publications

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“…In summary, the effect of different sizes and morphologies of eutectic silicon on thermal/electrical conductivity of the alloy needs to be investigated. Since some investigations show that Na, Sr [19], Eu [20], Ba [21] and Y [22] can modify eutectic silicon in fibrous shape, and Sb and Bi can modify eutectic silicon in fine flake shape [23], the addition of alloy elements can affect the eutectic morphology of the alloy [24]. In the study, the eutectic morphology of Al-8Si alloy would be controlled through the addition of elements Sr and Sb, in order to investigate the effect of the size and morphology of eutectic silicon of the alloy.…”

Section: Introductionmentioning

confidence: 99%

Effect of Modification with Different Contents of Sb and Sr on the Thermal Conductivity of Hypoeutectic Al-Si Alloy

Guo

Guan

Yan

et al. 2020

Metals

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In this paper, the effects of size, morphology and distribution of eutectic silicon on the thermal conductivity of Al-8Si alloy modified by Sr (0.04, 0.08, 0.12 wt.%) and Sb (0.1, 0.3, 0.5 wt.%) elements with T6 heat treatment were investigated. The results show that the modified fibrous eutectic silicon has a significant capability of improvement of thermal conductivity, while the amount of the modifier has a relatively weak effect on thermal conductivity. After T6 treatment, the fracture or spheroidization of the flake eutectic silicon and the disappearance of clustering phenomenon could raise thermal conductivity, but the coarsening of fibrous eutectic silicon is inconducive to thermal conductivity. Finally, the effect of eutectic silicon on electron transport is analyzed in detail, which could provide a reference for enhancing the thermal (or electrical) conductivity of hypoeutectic Al-Si alloy through effective microstructure control.

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Section: Introductionmentioning

confidence: 99%

Effect of Modification with Different Contents of Sb and Sr on the Thermal Conductivity of Hypoeutectic Al-Si Alloy

Guo

Guan

Yan

et al. 2020

Metals

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“…The value of less than 0.05 wt.% Ti is insufficient to modify the grain and α-Al dendrites. The increased barium content may also worsen characteristics due to the formation and growth of the intermetallic phase based on barium, for example, Al 2 Si 2 Ba [17], and an insufficient amount may lead to incomplete modification of eutectic silicon.…”

Section: Resultsmentioning

confidence: 99%

“…When barium is injected into the melt, the particles of eutectic silicon are refined and rounded. The main advantage of barium use is the long-term preservation of the modifying ability [15][16][17][18][19]. Barium fluoride is an available substance with a relatively low cost.…”

Section: Introductionmentioning

confidence: 99%

Complex Structure Modification and Improvement of Properties of Aluminium Casting Alloys with Various Silicon Content

Shlyaptseva

Petrov

Ryakhovsky

et al. 2021

Metals

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The possibility of using complex structure modification for aluminium casting alloys’ mechanical properties improvement was studied. The fluxes widely used in the industry are mainly intended for the modification of a single structural component of Al–Si alloys, which does not allow unifying of the modification process in a production environment. Thus, a new modifying flux that has a complex effect on the structure of Al–Si alloys has been developed. It consists of the following components: TiO2, containing a primary α-Al grain size modifier; BaF2 containing a eutectic silicon modifier; KF used to transform titanium and barium into the melt. The effect of the complex titanium dioxide-based modifier on the macro-, microstructure and the mechanical properties of industrial aluminium–silicon casting alloys containing 5%, 6%, 9%, 11% and 17% Si by weight was studied. It was found that the tensile strength (σB) of Al–Si alloys exceeds the similar characteristics for the alloys modified using the standard sodium-containing flux to 32%, and the relative elongation (δ) increases to 54%. The alloys’ mechanical properties improvement was shown to be the result of the flux component’s complex effect on the macro- and microstructure. The effect includes the simultaneous reduction in secondary dendritic arm spacing due to titanium, the refinement and decreasing size of silicon particles in the eutectic with barium and potassium, and the modifying of the primary silicon. The reliability of the studies was confirmed using up-to-date test systems, a significant amount of experimental data and the repeatability of the results for a large number of samples in the identical initial state.

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“…Refinement of eutectic Si could be an effective way to improve mechanical properties of Al-Si alloys [4,5]. Many strategies have been demonstrated to refine Si phase, such as adding alloy elements during casting [6], changing solidification rate [5,7], severe plastic deformation [3] and friction stir processing [8]. However, the size of Si phase is usually in the micron scale.…”

Section: Introductionmentioning

confidence: 99%

“…Although traditional hypoeutectic Al-Si alloys have heterogeneities such as Al dendrites and Al-Si eutectic domain, the synergistic effect between them is weak due to the coarse size of Si. Moreover, crack often preferentially nucleates at the boundary between Al dendrites and Al-Si eutectic [6,9,16]. Herein, we fabricated ultrafine heterogeneous Al-Si microstructure composed of nanoscale Al-Si eutectic and fine Al dendrites by laser rapid solidification (LRS).…”

Section: Introductionmentioning

confidence: 99%

In situ characterization of tensile behavior of laser rapid solidified Al–Si heterogeneous microstructures

Wei

Xie

et al. 2021

Materials Research Letters

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Heterogeneous Al-Si microstructure comprising of sub-micron-scale Al dendrites and nanoscale Al-Si fibrous eutectic was fabricated by processing as-cast Al-20wt.%Si alloy using laser rapid solidification. In situ tension tests explored high tensile strength ( ∼ 600 MPa) and ductility ( ∼ 10%) and high strain hardening rate ( ∼ 7 GPa). Microstructural characterization revealed the plastic codeformation mechanisms between soft Al dendrites and hard nanoscale Al-Si eutectic. The progression of plasticity in nanoscale Al-Si eutectic with increasing applied strain is accommodated by dislocation plasticity in the nano-Al channels and cracking Si nanofibers. The propagation of nano-cracks is suppressed by surrounding Al, retaining good ductility of the sample. IMPACT STATEMENTIn situ tension tests revealed the role of heterogeneous Al-Si microstructure in enhancing strain hardening rate and producing large back stresses and plasticity in sample even after fracture of nanoscale Si fibers.

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Modification of eutectic Si and the microstructure in an Al-7Si alloy with barium addition

Cited by 50 publications

References 23 publications

Effect of Modification with Different Contents of Sb and Sr on the Thermal Conductivity of Hypoeutectic Al-Si Alloy

Effect of Modification with Different Contents of Sb and Sr on the Thermal Conductivity of Hypoeutectic Al-Si Alloy

Complex Structure Modification and Improvement of Properties of Aluminium Casting Alloys with Various Silicon Content

In situ characterization of tensile behavior of laser rapid solidified Al–Si heterogeneous microstructures

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