Cooling thermal parameters, microstructural spacing and mechanical properties in a directionally solidified hypereutectic Al–Si alloy

Reyes, Rodrigo V.; Kakitani, Rafael; Costa, Thiago A.; Spinelli, José Eduardo; Cheung, Noé; Garcia, Amauri

doi:10.1080/09500839.2016.1192297

Cited by 24 publications

(9 citation statements)

References 29 publications

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“…An experimental study by Goulart et al 19 , reported the thermal parameters effect on the resulting microstructure and mechanical properties of hypoeutectic Al-Si alloys. Experimental results obtained by Goulart et al 19 20 have demonstrated the relationship between cooling thermal parameters, microstructural spacing and mechanical properties. Amongst results, as listed by the authors, refined globular Si particles seems to contribute for a combination of high tensile strength and elongation.…”

Section: Introductionmentioning

confidence: 94%

Effect of Solidification Processing Parameters and Silicon Content on the Dendritic Spacing and Hardness in Hypoeutectic Al-Si Alloys

et al. 2018

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Aluminium with silicon as alloying element, form a class of material providing the most significant part of all material casting manufactured materials. These alloys have a wide range of applications in the automotive and aerospace industries. It is widely recognized that moderate addition of silicon to aluminum, significantly improves the resulting mechanical properties. Hypoeutectic Al-Si alloys were used in the present experimental study to investigate the solidification parameters effect and Si 3-5 wt% addition on the microstructural features and resulting hardness in a vertical directional solidification system. The hypoeutectic alloys were directionally solidified under transient heat flow conditions in a range of cooling rates from 0.3 to 4 ºC/s. Characterization analyses by optical microscopy indicate clearly that secondary dendritic arm spacing (λ 2 ) increases significantly with the decrease in solidification speed (S P ) and cooling rate (Ṫ). On the other hand, experimental growth laws relating the secondary dendritic arm spacing (λ 2 ) to the solidification speed (S P ) and cooling rate (Ṫ) indicate that Si addition from 3 wt% to 5 wt% has induced a thickening effect leading to increase in λ 2 . While, experimental results have shown that the resulting hardness increase as solidification processing parameters (S P and Ṫ ) increase. Results of Vickers hardness test for Al-5 wt% Si alloy has hardness increase of 18 % from that of Al-3 wt% Si alloy with mean values of 26 and 22 HV, respectively.

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Section: Introductionmentioning

confidence: 94%

Effect of Solidification Processing Parameters and Silicon Content on the Dendritic Spacing and Hardness in Hypoeutectic Al-Si Alloys

et al. 2018

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“…Considering that the major microstructural characteristic constituting the samples is the spacing of the eutectic structure, λ Si , a method was required to describe the scale variation analysis of the spacing affecting the strength and ductility. Therefore, the application of "Hall-Petch" relationships to compare the present results with the previous results for binary the Al-15 wt.%Si was adopted 14 .…”

Section: Resultsmentioning

confidence: 99%

Effects of Bi Addition on Si Features, Tensile Properties and Wear Resistance of Hypereutectic Al-15Si Alloy

2020

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Bismuth (Bi) alloying in Aluminum (Al) alloys is considered of importance in special applications requiring improvements in the alloy machining. Despite that, the influence of Bi either on evolution of the solidification or on resulting microstructure of hypereutectic Al-Si alloys is still to be determined. The present research work is devoted to these requirements. In the present study, Al-15wt.% Si hypereutectic alloy is modified with 1.0 wt.% Bi. The effects of this addition on the morphology of the phases forming the microstructure and on the tensile/wear properties are investigated. Various samples characterized by distinct cooling rates are generated by transient directional solidification of the ternary Al-Si-Bi alloy. Microstructure is examined by optical microscopy and scanning electron microscopy (SEM) analyses, segregation by energy-dispersive X-ray spectroscopy (EDS) whereas wear and tensile properties have been characterized by standardized tests. The experimental variations of the eutectic spacing are compared to each other based on their trends. It is found that the addition of minor Bi content (~1 wt. %) permitted tensile strength and ductility of 195 MPa and 14%. Furthermore, wear resistance is improved by up to 20% due to the Bi addition. The reasons for that will be outlined.

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“…The molten alloy was degassed with argon gas for 2 minutes using a perforated quartz tube before being scorified with the appropriate flux and cast as 60 mm x 157 mm cylindrical ingots. A directional solidification method, as described in previous articles [23,24], was used to achieve nonstationary heat flow conditions during the production of the castings. To allow continuous temperature measurements during solidification, 8 fine K-type thermocouples were mounted along the length of the casting.…”

Section: Methodsmentioning

confidence: 99%

Relationship Between Microstructure Evolution and Tensile Properties of AlSi10mg Alloys With Varying Solidification Cooling Rates

Gandolfi¹,

Mg²,

Lf³

et al. 2021

Preprint

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This work explored and contrasted the effect of microstructure on the tensile properties of AlSi10Mg alloys generated by transient directional solidification depending on variations in cooling rate and Magnesium (Mg) content (i.e., 0.45 and 1wt.% Mg), with a focus on understanding the dendritic growth and phases constitution. Optical and Scanning electron (SEM) microscopies, CALPHAD and thermal analysis were used to describe the microstructure, forming phases and resulting tensile properties. The findings showed that the experimental evolution of the primary dendritic spacing is very similar when both directionally solidified (DS) Al-10wt.% Si-0.45wt.% Mg and Al-10wt.% Si-1wt.% Mg alloys samples are compared. The secondary dendritic spacing was lower for the alloy with more Mg, especially considering the range of high growth velocities. Moreover, a greater fraction of (Al+Si+Mg2Si) ternary eutectic islands surrounding the -Al dendritic matrix was noted for the alloy with 1wt.% Mg. As a result of primary dendritic spacings greater than 180 m related to lower cooling rates, slightly higher tensile properties were attained for the Al-10wt.% Si-0.45wt.% Mg alloy. In contrast, combining dendritic refining (< 150 m) and larger Mg2Si fraction, fast solidified DS Al-10wt.% Si-1wt.% Mg samples exhibited higher tensile strength and elongation. The control of cooling rate and fineness of the dendritic array provided a new insight related to the addition of Mg in slightly higher levels than conventional ones, capable of achieving a better balance of tensile properties in AlSi10Mg alloys.

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Cooling thermal parameters, microstructural spacing and mechanical properties in a directionally solidified hypereutectic Al–Si alloy

Cited by 24 publications

References 29 publications

Effect of Solidification Processing Parameters and Silicon Content on the Dendritic Spacing and Hardness in Hypoeutectic Al-Si Alloys

Effect of Solidification Processing Parameters and Silicon Content on the Dendritic Spacing and Hardness in Hypoeutectic Al-Si Alloys

Effects of Bi Addition on Si Features, Tensile Properties and Wear Resistance of Hypereutectic Al-15Si Alloy

Relationship Between Microstructure Evolution and Tensile Properties of AlSi10mg Alloys With Varying Solidification Cooling Rates

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