The varied mechanisms of yttrium (Y) modifying a hypoeutectic Al–Si alloy under conditions of different cooling rates

Mao, Guoling; Yan, Han; Zhu, Congcong; Wu, Zhen; Gao, Wenli

doi:10.1016/j.jallcom.2019.07.107

Cited by 71 publications

(23 citation statements)

References 36 publications

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“…Several routes, such as chemical modification, solution heat treatment, and deformation, have been used to attain a fine ideal microstructure and to modify the morphology of the Si particles [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. The chemical modification and heat treatment methods are constrained by economy, resources, and environment.…”

Section: Introductionmentioning

confidence: 99%

Influence of Modification on Flow Stress Behavior and Corrosive Properties of a Hypoeutectic Al-Si Alloy

Song

Huang³

et al. 2022

Materials

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The flow stress behavior and corrosive properties of Al-7Si alloy were studied by thermal compression test, electrochemical test, and electron probe microanalysis. The influences of temperatures, strain rates, strains, and morphology of Si particles on stress-strain curves of Al-7Si alloy were analyzed. The peak stress of unmodified-Al-7Si alloy is higher than that of Sr-modified-Al-7Si alloy at the same deformation conditions, and the phenomenon is obviously relevant to the distribution and morphology of Si particles. The morphology of Si particles of unmodified-undeformed-Al-7Si alloy is a typical thick layer, and that of unmodified-deformed-Al-7Si alloy is broken into relatively small particles and the distribution is relatively even in homogeneous deformation zone II. The distribution of Si particles in Sr-modified-deformed-Al-7Si alloy is obviously more even than undeformed alloy. The effect of a small deformation of 20% on the distribution and morphology of Si particles is obviously smaller than that of a large deformation of 50%. The electrochemical self-corrosion potential of Sr-modified-Al-7Si alloy is higher than that of unmodified-Al-7Si alloy, and it proves that the distribution and morphology of Si particles have a certain influence on the corrosive properties of Al-7Si alloy. That is, the even fine Si particles are more conducive to improving the corrosive properties of Al-7Si alloy.

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Section: Introductionmentioning

confidence: 99%

Influence of Modification on Flow Stress Behavior and Corrosive Properties of a Hypoeutectic Al-Si Alloy

Song

Huang³

et al. 2022

Materials

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“…However, it is not clear which degree of influence is more significant if comparing cooling rate with modification by Sr element. Moreover, cooling rates may also cause different modification mechanisms [18,19], which indicates that the influences of cooling rates and modification on the thermal conductivity are coupling and complicated. In this study, therefore, the individual/coupling influences of cooling rates and modification by Sr element on the thermal conductivity of Al-Si hypoeutectic alloys will be investigated, which aims to clarity the mechanism for linking microstructures with the thermal conductivity, and evaluate the degree of their individual/coupling influences.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rate and Modification by Strontium on the Thermal Conductivity of Al-8Si Alloy

Wang

Guan

Wang

et al. 2021

Metals

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Cooling rate plays a critical role in determining the thermal conductivity of Al-Si alloys. Although the effect of morphology and size of Si (changed by heat treatment) on its thermal conductivity has been investigated, the effect of cooling rates on thermal conductivity has not been well studied. In this study, we investigated the microstructure of an Al-8Si (with and without modification by Strontium (Sr)) alloy with cooling rates from 46.2 °C/s to 234 °C/s. It was found that the effect of cooling rate on thermal conductivity of Sr modification and Sr-free samples are opposite from each other. As a result, while the cooling rate increased from 46.2 °C/s to 234 °C/s, the calculated thermal conductivity increased from 145.3 MS/m to 151.5 MS/m for Sr-free Al-8Si alloy, and the calculated thermal conductivity was reduced from 187.5 MS/m to 176.7 MS/m for the Sr-modified Al-8Si alloy. By discussing how thermal conductivity correlates with eutectic silicon morphology and secondary dendrite arm spacing, the relationship between cooling rate and thermal conductivity were explained. This work suggests a new design strategy for improving the thermal conductivity of Al-Si hypoeutectic alloys.

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“…For eutectic Si modified by RE elements, it is accepted that the modification effect has a close relationship with the cooling condition in casting process. Mao et al [15] pointed out different modification mechanisms exist in hypoeutectic Al-Si alloys modified with yttrium (Y) in different cooling rates. Liu et al [16] investigated the microstructural evolution of Si in Al-Si alloys modified with Ce-rich mischmetal at different cooling rates and concluded that effective modification is obtained by a combination of the RE elements and rapid cooling rate.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rates on the Microstructure and Mechanical Property of La Modified Al7SiMg Alloys Processed by Gravity Die Casting and Semi-Solid Die Casting

Feng

et al. 2020

Metals

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Rare earth (RE) additions are capable of refining the α-Al phase as well as modifying the eutectic Si particles of alloys. The cooling rate in casting process should be carefully concerned when the Al-Si alloys are refined and modified by adding RE elements. In this study, the effect of cooling rates on the microstructure and mechanical properties of La modified Al-7.0Si-0.3Mg alloys was studied in gravity die casting and semi-solid die casting. It is found that in La modified Al-7.0Si-0.3Mg alloys, with increasing the cooling rate from 0.2 to 9 K/s in gravity die casting, the α-Al grains are greatly refined and the Si particles are modified to branching morphology, which evidently increases the UTS and elongation of alloys. In addition, when increasing the cooling rate from 30 to 130 K/s in semi-solid die casting, the α-Al grains are refined from 140 to 47 μm, and the Si particles are modified to fibrous morphology, which increases the UTS from 190 to 230 MPa and elongation from 10% to 11%. However, the 0.4 wt.% La addition results to La-rich phases formed in microstructure, which impairs the mechanical properties of Al-7.0Si-0.3Mg alloys in semi-solid die casting.

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The varied mechanisms of yttrium (Y) modifying a hypoeutectic Al–Si alloy under conditions of different cooling rates

Cited by 71 publications

References 36 publications

Influence of Modification on Flow Stress Behavior and Corrosive Properties of a Hypoeutectic Al-Si Alloy

Influence of Modification on Flow Stress Behavior and Corrosive Properties of a Hypoeutectic Al-Si Alloy

Effect of Cooling Rate and Modification by Strontium on the Thermal Conductivity of Al-8Si Alloy

Effect of Cooling Rates on the Microstructure and Mechanical Property of La Modified Al7SiMg Alloys Processed by Gravity Die Casting and Semi-Solid Die Casting

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