Thermodynamic evaluation of the thixoformability of Al–Si alloys

Zoqui, Eugênio José; Benati, Davi Munhoz; Proni, Cecília Tereza Weishaupt; Torres, Luis Vanderlei

doi:10.1016/j.calphad.2015.12.006

Cited by 27 publications

(17 citation statements)

References 10 publications

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“…The Rheocast Quality Index (RQI = (GLS * SF)/GS) gives the relationship of those features where a perfect structure in which a grain is a perfect globule leads to a RQI = 1. As described in previous paper [14], this work also used Thermo-Calc5 simulation; the percentages of copper, magnesium, iron, and titanium were taken into account, but residual elements, such as manganese, chromium, nickel, and zinc, were not. Thermo-Calc predicts solidus temperature of 525 ∘ C, liquidus temperature of 627 ∘ C, and, for expected 60% solid fraction, processing temperature of 584 ∘ C. Based on the chemical composition of the alloy obtained by optical emission spectrometry, the expected phase diagram was drawn using the Thermo-Calc software.…”

Section: Methodsmentioning

confidence: 99%

Electromagnetic Stirring versus ECAP: Morphological Comparison of Al-Si-Cu Alloys to Make the Microstructural Refinement for Use in SSM Processing

Torres

Zoqui

2016

Advances in Materials Science and Engineering

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This work evaluates the morphological evolution at the semisolid state of the Al-4.0wt%Si-2.5wt%Cu alloy produced by direct chill casting under electromagnetic stirring (EMS) and by one equal channel angular pressing (ECAP) pass. The ECAP emerged as a promising technique capable of reduction and homogeneous metals microstructure imposing large deformations occurs in a matrix that contains two channels of the same cross-sectional area and forms an angle of 120°. The materials were submitted to reheating treatment in condition of 60% solid fraction at treatment times of 0, 30, and 90 s. Comparing the two cases, we have the presented ECAP process that had an excellent response to the recovery and recrystallization mechanisms, and refined microstructures ideal for thixoforming were produced. Primary particle sizes of about 45 μm and grain sizes of about 75 μm and a circularity shape factor of more than 0.60 were obtained. The low silicon alloy, Al-4.0wt%Si-2.5wt%Cu, presented excellent refinement when processed via equal channel angular pressing, presenting good morphological stability at the semisolid state, without significant changes in size or shape of the solid particles. This fully globular structure is favourable for thixoforming processes.

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Section: Methodsmentioning

confidence: 99%

Electromagnetic Stirring versus ECAP: Morphological Comparison of Al-Si-Cu Alloys to Make the Microstructural Refinement for Use in SSM Processing

Torres

Zoqui

2016

Advances in Materials Science and Engineering

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“…These alloys can have compatibility issues with semi-solid processing. An alloy's flexibility towards semi-solid processing depends on parameters such as solidification range, fraction liquid sensitivity and window processing temperature [9], [10]. The literature points out that, most of the semi-solid processing studies were reported with commercial alloys such as Aluminium A356, A357, 6082, 7075, 206 and Mg alloys such as AM60, etc.…”

Section: Introductionmentioning

confidence: 99%

“…However, except for A356 alloy the other alloy systems have practical challenges in semi-solid processing such as lack of process control, hot tearing, lack of fusion etc. [9]- [12]. Hence, to assess the alloy compatibility, it is vital to understand the phase transitions involved in the alloy system, understanding of initial microstructure and its rheological behaviour.…”

Section: Introductionmentioning

confidence: 99%

CALPHAD Approach to Understand the Semi-Solid Processing Parameters of Al-6Si-4Cu Alloy

Gopalakrishnan¹,

Senthilkumar²

2021

Proceedings of the First International Conference on Combinatorial and Optimization, ICCAP 2021, December 7-8 2021, Chennai, In

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Semi-solid processing has some prerequisites such as the feedstock alloy must meet certain thermodynamic criteria. Therefore, to reap the full benefits of semi-solid processing, it is important to assess the compliance of commercial aluminium alloys for semi-solid processing. Hence in the current paper, thermodynamic parameters for semisolid processing of 6,7 and y=3,4,5) alloys were assessed using CALPHAD approach. The results show that the thermodynamic simulation is effective in predicting the amenability of alloys for semi-solid processing. Also inferred that the variation of alloy composition within the ASTM standard range itself varies the solidification behaviour and this variation can affect semi-solid processing. Thus, a Taguchi L9 orthogonal array is constructed for various alloy compositions and based on the L9 array, the solidification curves were simulated by CALPHAD Approach. The best suited alloy and its thermodynamic parameters for semi-solid processing were identified. The simulated data for the best alloy composition is validated with the help of computer aided cooling curve analysis.

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“…As ligas de alumínio são as de maior aplicação nos processos que envolvem materiais semissólidos, no entanto, as ligas alumínio-silício apresentam destaque quando comparadas com outras, ocupando 95% de todas as aplicações, enquanto que todas as outras ligas somadas representam somente 5% [9]. Nas últimas décadas, ocorreram avanços significativos nos estudos sobre o processo de tixoconformação, objetivando a melhor forma de produção da matéria-prima e consequentemente a obtenção de microestruturas refinadas e homogêneas, com bom comportamento reológico e com boas propriedades mecânicas [10,11,12,13,14]. Portanto, as razões que fundamentam este trabalho e, ao mesmo tempo, apresentam as justificativas do trabalho podem ser compreendidas segundo alguns aspectos, a saber: este estudo tem como objetivo contribuir para o desenvolvimento do processo de tixoconformação, além da utilização de outras famílias de ligas de alumínio, contribuindo para o desenvolvimento de novas matérias-primas.…”

Section: Introductionunclassified

Caracterização microestrutural das ligas AA7004 e AA7075 tixoforjadas em prensa excêntrica

Torres

Zoqui

2019

Matéria (Rio J.)

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RESUMO Este trabalho tem como objetivo analisar o processo de tixoforjamento em prensa excêntrica das ligas aeronáuticas AA7004 e AA7075 e compreender o comportamento do material semissólido durante o preenchimento da matriz através de análises microestruturais. As ligas foram submetidas a tratamentos térmicos de globularização pelo tempo de 210 s e fração líquida de 55% e na sequência tixoforjadas. As temperaturas de trabalho foram determinadas via ensaios de DSC (differential scanning calorimetry). O tratamento térmico de globularização tem como objetivo efetuar a globularização parcial ou total das ligas, permitindo analisar a evolução microestrutural. A força máxima aplicada no ensaio de tixoforjamento foi de aproximadamente 500 kg, sendo que a capacidade da prensa excêntrica segundo seu fabricante é de 25 toneladas, demonstrando que a carga utilizada para a realização dos ensaios foi irrisória em comparação com a capacidade do equipamento. O produto final apresentou total preenchimento da matriz e qualidade dimensional. A região localizada no centro da peça, onde ocorreu a maior deformação apresentou grãos deformados e menores em relação às outras regiões, a saber, a liga AA7004 apresentou tamanho de grãos de 142 µm e a liga AA7075 apresentou tamanho de grãos de 105 µm.

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Thermodynamic evaluation of the thixoformability of Al–Si alloys

Cited by 27 publications

References 10 publications

Electromagnetic Stirring versus ECAP: Morphological Comparison of Al-Si-Cu Alloys to Make the Microstructural Refinement for Use in SSM Processing

Electromagnetic Stirring versus ECAP: Morphological Comparison of Al-Si-Cu Alloys to Make the Microstructural Refinement for Use in SSM Processing

CALPHAD Approach to Understand the Semi-Solid Processing Parameters of Al-6Si-4Cu Alloy

Caracterização microestrutural das ligas AA7004 e AA7075 tixoforjadas em prensa excêntrica

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