Study of Strontium Fading in Al-Si-Mg AND Al-Si-Mg-Cu Alloy by Thermal Analysis

Eguskiza, Saioa; Niklas, Andrea; Fernández-Calvo, Ana Isabel; Santos, Fernando; Djurdjevic, Mile B.

doi:10.1007/bf03355622

Cited by 24 publications

(23 citation statements)

References 9 publications

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“…At a holding time of 240 minute, the morphology of the eutectic Si phase completely reverted to its unmodified state (Figure 4i). Obviously, Sr lost its modification potential, a phenomenon known as the fading effect [7,24], because of the amount of Sr which was lost. This is also confirmed by a composition test shown in Figure 5a.…”

Section: Resultsmentioning

confidence: 99%

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The Relationship between Residual Amount of Sr and Morphology of Eutectic Si Phase in A356 Alloy

Zhang

Wei

et al. 2019

Materials

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This paper studied the relationship between the residual amount of Sr and the morphology of the eutectic Si phase in A356 obtained through different modification treatment processes; additionally, the cooling rates of molds were studied. The eutectic Si phase revealed a satisfactory modification effect at residual Sr amounts above 0.01 wt % in A356 alloys cast using an iron mould. Complete modification of the eutectic Si phase could be achieved at a Sr additive amount 0.03 wt % in an A356 melt. The addition of higher amounts of Sr (~0.04–0.06 wt %) did not improve the modification effect. With the addition of 0.06 wt % Sr into A356 alloy melt and holding at 750 °C, the anti-fading capacity of Sr modification effect could be sustained for 120 minutes. More Sr is needed to obtain a good modification of eutectic Si for an A356 alloy cast using a sand mold.

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Section: Resultsmentioning

confidence: 99%

“…The difference in the critical value from our result may be due to different alloys with different alloying elements and different smelting processes which lead to different loss levels of Sr. Therefore, to be on the safe side, 250–300 ppm [24,25] is usually preferred in typical foundry applications.…”

Section: Resultsmentioning

confidence: 99%

The Relationship between Residual Amount of Sr and Morphology of Eutectic Si Phase in A356 Alloy

Zhang

Wei

et al. 2019

Materials

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“…where [°C] is the eutectic growth temperature of the modified alloy determined from the cooling curve and its first derivative and [°C] is the eutectic growth temperature of the unmodified alloy determined from the chemical composition of the alloy using the following equation [39]:…”

Section: Thermal Analysismentioning

confidence: 99%

Investigation on Double Oxide Film Initiated Pore Formation in Aluminum Casting Alloys

Gyarmati,

Fegyverneki,

Tokár

et al. 2020

IJEMS

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The most common, and in fact, the most deleterious defects of aluminum casting alloys are the so-called double oxide films or bifilms, which have a central role in porosity formation, as they can easily unfurl and inflate into pores during the solidification of the alloys. Sr addition is generally used in the foundry industry for the modification of the eutectic Si phase of hypoeutectic Al-Si alloys. However, Sr microalloying usually leads to an increased pore formation tendency. As bifilms are preferred sites for pore formation, it should be expected that Sr additions have a significant effect on the number and/or the structure of double oxide films present in the melt. In this work, the relationship between Sr-concentration and the susceptibility to pore formation has been investigated through the evaluation of melt quality of melts which had different levels of Sr. The bifilm content of the melts was investigated by the analysis of K-mold specimens and X-ray computed tomography (CT) of reduced pressure test (RPT) samples. It was found that liquid alloys with a higher Sr concentration had a significantly greater tendency to pore formation, which can be explained by the presence of a larger number of bifilm defects in the liquid alloy.

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“…In particular, DT E is calculated as the difference between T G,E of the base alloy and those of the alloys modified with different amounts of Sr, and Dt PL is the time interval from T MIN,E to the moment at which T MIN,E is reached again after the recalescence. 27…”

Section: Thermal Analysismentioning

confidence: 99%

Comprehensive Evaluation of Modification Level Assessment in Sr-Modified Aluminium Alloys

et al. 2017

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One way to improve the mechanical properties of Al-Si alloys is to add chemical modifiers that affect the microstructure of the cast components. Small amounts of Sr cause the modification of the eutectic Si particles from a coarse plate-like morphology into a fine fibrous one. This study sets out to analyse the effects of chemical modification on an Al-7%Si-0.3%Mg foundry alloy treated with Sr, ranging from 62 to 820 ppm. Assessment of modification level was evaluated by both thermal analysis technique and quantitative microstructural investigations. Up to now, little attention has been paid to the role played by microstructural characteristics in evaluating the modification level, which is commonly performed by comparison with standard images. In the present investigation, numerical methods proposed in the literature have been considered in an attempt to understand their effectiveness. The correlation between thermal analysis results and geometrical parameters of eutectic Si particles highlighted the impact of microstructural homogeneity on modification-level evaluation. In addition, the presence of Ca in Srbased intermetallics has been further investigated by means of scanning electron microscopy combined with energy-dispersive X-ray spectroscopy.

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Study of Strontium Fading in Al-Si-Mg AND Al-Si-Mg-Cu Alloy by Thermal Analysis

Cited by 24 publications

References 9 publications

The Relationship between Residual Amount of Sr and Morphology of Eutectic Si Phase in A356 Alloy

The Relationship between Residual Amount of Sr and Morphology of Eutectic Si Phase in A356 Alloy

Investigation on Double Oxide Film Initiated Pore Formation in Aluminum Casting Alloys

Comprehensive Evaluation of Modification Level Assessment in Sr-Modified Aluminium Alloys

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