Formation of Iron-Rich Intermetallic Phases in Al-7Si-Mg: Influence of Cooling Rate and Strontium Modification

Santos, Jorge; Jarfors, Anders E. W.; Dahle, A. K.

doi:10.1007/s11661-019-05343-5

Cited by 14 publications

(5 citation statements)

References 54 publications

(150 reference statements)

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“…An agglomeration of Al2O3 nanoparticles was also reported in [37,40]. The needle-like intermetallic phases present in the microstructures of both matrix alloy and composite are β-Al5FeSi which are also noticed in the literature [36,[41][42][43]. Irregularly shaped light-coloured phases contain Al-Ni-Cu-(Fe).…”

Section: Methodsmentioning

confidence: 54%

Tribological Behaviour of Hypereutectic Al-Si Composites: A Multi-Response Optimisation Approach with ANN and Taguchi Grey Method

Miladinović,

Gajević,

Savić

et al. 2024

Lubricants

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An optimisation model for small datasets was applied to thixocasted/compocasted composites and hybrid composites with hypereutectic Al-18Si base alloys. Composites were produced with the addition of Al2O3 (36 µm/25 nm) or SiC (40 µm) particles. Based on the design of experiment, tribological tests were performed on the tribometer with block-on-disc contact geometry for normal loads of 100 and 200 N, a sliding speed of 0.5 m/s, and a sliding distance of 1000 m. For the prediction of the tribological behaviour of composites, artificial neural networks (ANNs) were used. Three inputs were considered for ANN training: type of reinforcement (base alloy, Al2O3 and SiC), amount of Al2O3 nano-reinforcement (0 and 0.5 wt.%), and load (100 and 200 N). Various ANNs were applied, and the best ANN for wear rate (WR), with an overall regression coefficient of 0.99484, was a network with architecture 3-15-1 and a logsig (logarithmic sigmoid) transfer function. For coefficient of friction (CoF), the best ANN was the one with architecture 3-6-1 and a tansig (hyperbolic tangent sigmoid) transfer function and had an overall regression coefficient of 0.93096. To investigate the potential of ANN for the prediction of two outputs simultaneously, an ANN was trained, and the best results were from network 3-5-2 with a logsig transfer function and overall regression coefficient of 0.99776, but the predicted values for CoF in this case did not show good correlation with experimental results. After the selection of the best ANNs, the Taguchi grey multi-response optimisation of WR and CoF was performed for the same combination of factors as the ANNs. For optimal WR and CoF, the combination of factors was as follows: composite with 3 wt.% Al2O3 micro-reinforcement, 0.5 wt.% Al2O3 nano-reinforcement, and a load of 100 N. The results show that developed ANN, the Taguchi method, and the Taguchi grey method can, with high reliability, be used for the optimisation of wear rate and coefficient of friction of hypereutectic Al-Si composites. Microstructural investigations of worn surfaces were performed, and the wear mechanism for all tested materials was light abrasion and adhesion. The findings from this research can contribute to the future development of hypereutectic Al-Si composites.

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Section: Methodsmentioning

confidence: 54%

Tribological Behaviour of Hypereutectic Al-Si Composites: A Multi-Response Optimisation Approach with ANN and Taguchi Grey Method

Miladinović,

Gajević,

Savić

et al. 2024

Lubricants

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“…The morphology of the eutectic Si was observed at a higher magnification using deep-etched samples, as shown in Figure 4. As seen in Figure 4a,b, sample A exhibited the expected eutectic Si coarse plate shape that commonly grows epitaxially from the α-Al dendrites and induces stress concentration that is detrimental to strength and ductility [20]. Even though the shape of the eutectic Si of sample B was similar to sample A, thinner plates were found in the US-treated (sample B) mostly due to the chill modification effect promoted by US treatment.…”

Section: Resultsmentioning

confidence: 94%

Impact of the Ultrasonic-Assisted Casting of an AlSi7Mg Alloy on T6 Heat Treatment

Gomes

Grilo

Carneiro

et al. 2023

Metals

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In this work, the effect of ultrasonic vibration during solidification on the aging kinetics of an AlSi7Mg alloy is investigated. With the ultrasonic equipment coupled to the mold walls, melt treatment was performed by two approaches: (i) fully above liquidus (>635 °C); and (ii) in the full range between liquidus and solidus (630 °C→ 550 °C). Cast samples were then subjected to T6 heat treatment for different aging times. It is shown that indirect ultrasound treatment increases the cooling rate while active. The eutectic Si was refined and further modified when ultrasound treatment was performed in the semisolid state. Due to the significant release of solute during the decomposition of π-Al8FeMg3Si6 into fine β-Al5FeSi, this has a significant impact in the solution stage. Ultrasound treatment fully above liquidus decreased the underaging time to 50% and peak aging time to 25% without compromising strength. The results suggest aging kinetics are correlated with a higher vacancy density and solute enrichment which favors Guinier–Preston (GP) zone formation. These findings show a promising route to tailor the aging kinetics in these alloys by selectively modifying phases and cooling rates.

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“…Usually, the β and π-Fe phases are produced as plate-like and Chinese-script morphologies, respectively during the solidification [47]. Nevertheless, Santos [62] and Caceres [52] revealed that Sr modification of A356/357 alloy poisons the β-Fe phase nucleation sites and promotes the formation of the π-Fe phase as plate-like morphologies. Therefore, it is quite logical that the π-Fe phase in B-0 and B-1 alloys appeared as plate/needle-like morphologies due to the Sr modification.…”

Section: Discussionmentioning

confidence: 99%

Concurrent effects of various B additions on grain refinement, Fe intermetallics morphologies, and ductility evolution of Al-7.5Si-0.55 Mg (A357) cast alloy

et al. 2020

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Simultaneous effects of boron (B) additions on grain refinement, morphological changes in Fe-intermetallic compounds, and consequent variations in mechanical responses of the cast Al-7.50Si-0.55 Mg (A357) alloys are evaluated in this research work. The contents B are varied from 0.002 to 0.40 wt. % and subsequent changes in the grain size and Feintermetallics morphologies are assessed through polarized light images, optical micrography, and scanning electron microscopy. A small addition of B (0.04 wt. %) yields identical refinement result (620 µm) as noted for commercial grain refiner Al-5Ti-1B (642 µm); whereas, the higher amount (0.40 wt. % of B) reduces the grain size up to 44% (360 µm). In as-cast state, the structure of the π-Fe phase is transmuted from plate/needle-type to Chinese-script particles for increased quantities (0.10 ~ 0.40 wt. %) of B. Contrarily, the heat-treatment (T6) causes the depletion of Mg and B from the π-Fe phase Chinese-script morphologies and disintegrates them by creating segregated regions of Fe particles. These agglomerated areas of Fe particles act as stress concentration points during tensile loading and considerably decrease the ductility values from 6.7 to 1.8%. Therefore, it implies that great care must be taken while developing B containing grain refiners.

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Formation of Iron-Rich Intermetallic Phases in Al-7Si-Mg: Influence of Cooling Rate and Strontium Modification

Cited by 14 publications

References 54 publications

Tribological Behaviour of Hypereutectic Al-Si Composites: A Multi-Response Optimisation Approach with ANN and Taguchi Grey Method

Tribological Behaviour of Hypereutectic Al-Si Composites: A Multi-Response Optimisation Approach with ANN and Taguchi Grey Method

Impact of the Ultrasonic-Assisted Casting of an AlSi7Mg Alloy on T6 Heat Treatment

Concurrent effects of various B additions on grain refinement, Fe intermetallics morphologies, and ductility evolution of Al-7.5Si-0.55 Mg (A357) cast alloy

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