The effects of cell spacing and distribution of intermetallic fibers on the mechanical properties of hypoeutectic Al–Fe alloys

Goulart, Pedro R.; Spinelli, José Eduardo; Cheung, Noé; Garcia, Amauri

doi:10.1016/j.matchemphys.2009.08.063

Cited by 93 publications

(47 citation statements)

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“…A presença da fase Al 6 Fe se deve à existência de Fe na composição do alumínio comercialmente puro, além da afinidade entre o Al e o Fe em altas temperaturas, favorecendo a difusão do Fe presente na lingoteira para a liga. A intensidade do pico desta fase Al 6 Fe se mostrou aumentar, para ambas as ligas, à medida que se distancia da interface metal/molde, já que a macrosegregação do Fe em alumínio é direta [24]. A fase em equilíbrio ρ-Ag 2 Al não foi detectada pelo ensaio de Difração de Raios-X o que pode ser explicado pela sensibilidade da técnica que necessita de, pelo menos, 5% em peso da fase.…”

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Influência na microestrutura e na microdureza decorrente da adição de 4%Ag na liga Al-4%Cu solidificada unidirecionalmente

et al. 2015

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RESUMODiversas aplicações industriais, tais como nos setores automotivo e aeronáutico, que necessitam de resistência e tenacidade, utilizam ligas do sistema Al-Cu. As ligas do sistema ternário Al-Cu-Ag são empregadas como modelo para o estudo de ligas eutéticas ternárias, além do uso em certo número de aplicações técnicas. Estudos relacionados aos efeitos da adição de Ag em ligas do sistema Al-Cu solidificadas em regime transitório, sob aspectos microestruturais e de microdureza, não são encontrados na literatura. Nesse sentido, o objetivo principal deste trabalho consiste na investigação dos efeitos da adição de 4%Ag na liga Al-4%Cu solidificada unidirecionalmente no sentido vertical ascendente em regime transitório, abordando análises de microestrutura, microdureza e parâmetros de solidificação dados pela velocidade de crescimento (V L ) e pela taxa de resfriamento (Ṫ). São apresentadas leis experimentais para as ligas Al-4%Cu e Al-4%Cu-4%Ag que correlacionam os espaçamentos dendríticos primário (λ 1 ) e secundário (λ 2 ) com V L e Ṫ. Foram realizadas análises de Difração de Raios-X (DRX) para a caraterização das fases cristalinas dos compostos presentes na microestrutura das ligas. O difratograma da liga binária mostrou a presença dos intermetálicos θ-Al 2 Cu, Al-Cu, Al 4 Cu 9 e Al 6 Fe e, para o caso da liga ternária, adicionalmente foi detectado o intermetálico µ-Ag 3 Al. Composições químicas de regiões do contorno da dendrita, assim como de seu interior, foram obtidas com o auxílio de um microscópio eletrônico de varredura (MEV) acoplado a um sistema de análise por energia dispersiva (EDS). Diversas posições ao longo do lingote foram analisadas através da técnica de Fluorescência de Raios-X (FRX) com objetivo de se detectar a existência de macrossegregação. Constatou-se que a microdureza não é influenciada pelas duas formas de espaçamentos da matriz rica em Al. Os intermetálicos ρ-Ag 2 Al e µ-Ag 3 Al são responsáveis pelo aumento de dureza devido a sua interação com o espaçamento dendrítico terciário e outros intermetálicos.Palavras-chave: solidificação, ligas de alumínio, microestrutura, microdureza, adição de prata. ABSTRACTAl-Cu alloys are used in several industrial applications, such as automotive and aerospace manufacturing, which demand mechanical strength and toughness performances. The Al-Cu-Ag ternary alloy system has been investigated to obtain a better understanding on ternary eutectic alloys besides its inherent applications. However, studies concerning the effects on microstructure and hardness due to Ag addition on Al-Cu alloys solidified under transient conditions, are not found in literature. In this sense, the main objective of this work consists in investigating the solidification parameters such as growth (V L ) and cooling (Ṫ) rate, microstructure and microhardness regarding the effects of adding 4wt% Ag on a Al-4wt%Cu alloy

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Influência na microestrutura e na microdureza decorrente da adição de 4%Ag na liga Al-4%Cu solidificada unidirecionalmente

et al. 2015

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“…The coefficients of the equations were defined by the least squares method. Several authors 19,23,24,25,26 used this methodology. These authors also primarily use PDAS, not the secondary dendritic arm spacing (SDAS), in columnar structures.…”

Section: Resultsmentioning

confidence: 99%

An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

et al. 2018

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Metals solidification involves the transformation of the molten metal back into the solid state. Solidification structures impact heavily on the final product's characteristics. The microstructure effects on metallic alloys properties have been highlighted in various studies and particularly the dendrite arm spacing influence upon the mechanical properties such as tensile strength has been reported. In the present investigation, Al-10wt%Si-2wt%Cu and Al-10wt%Si-5wt%Cu alloys were directionally solidified upward under transient heat flow conditions. The experimental results include solidification thermal parameters such as tip growth rate and cooling rate, optical microscopy, volume fraction of the eutectic mixture, primary dendritic arm spacing and ultimate tensile strength. Experimental growth laws of primary dendrite arm spacing as a function of the solidification thermal parameters are proposed. The Hall-Petch mathematical expressions were used to correlate the ultimate tensile strength as a function of the primary dendritic arm spacing. It was found that the alloy with higher copper content had a more refined structure. More refined structures had higher ultimate tensile strength values.

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“…As the values of ultimate (UTS) and yield (YTS) tensile strength are well known for these alloys 15 , a reference value concerning the flexural stress (27.4MPa) was adopted as 40% of the UTS value or 60% of the YTS obtained for the Al-0.5wt%Fe alloys, which are lower typically than the UTS and YTS values obtained for the Al-1.0 and 1.5wt%Fe alloys. The value imposed for the fatigue tests conducted in the present study is quite reasonable since the literature 16 indicates that fatigue strength limit is, in practice, around 50-60% of the UTS value for a given alloy.…”

Section: Methodsmentioning

confidence: 99%

“…All the investigations have showed that if the dendrite arm spacing is decreased, the mechanical properties of the cast alloy may be improved. Goulart et al 15 have carried out a study on the effects of iron content and cooling rate on the cell growth of hypoeutectic Al-Fe alloys and further on the development of tensile test parameters like ultimate tensile strength (σ u ), yield tensile strength (σ y ) and elongation (δ). It was shown that the microstructural arrangement strongly affects σ u , σ y and δ. Hall-Petch type relationships were proposed as follows corresponding to the ultimate tensile strength:…”

Section: Introductionmentioning

confidence: 99%

Effects of cellular growth on fatigue life of directionally solidified hypoeutectic Al-Fe Alloys

Ribeiro

Silva

et al. 2014

Mat. Res.

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Al-Fe hypoeutectic alloys are a family of casting alloys characterized by cell growth, low cost and appreciable formability. It is well known that fatigue strength is a requirement of prime importance considering the nature of load typically observed during operations involving the risers used in oil extraction. The aim of this study is to examine the influence of cell size and its intercellular phase distribution on the fatigue life (N f ) of the directionally solidified Al-0.5, 1.0 and 1.5wt% Fe alloys. A water-cooled vertical upward unidirectional solidification system was used to provide the castings. Microscopy light and SEM microscopy were used. It was found that fatigue life decreases as cell spacing (λ c ) increases. Smaller cell spacing allows a homogeneous distribution of Al-Fe fibers to happen within the intercellular regions, which tends to improve the mentioned fatigue property. ); where A and B are constants] seems to be able to encompass the fatigue life variation along the Al-Fe alloys.

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The effects of cell spacing and distribution of intermetallic fibers on the mechanical properties of hypoeutectic Al–Fe alloys

Cited by 93 publications

References 18 publications

Influência na microestrutura e na microdureza decorrente da adição de 4%Ag na liga Al-4%Cu solidificada unidirecionalmente

Influência na microestrutura e na microdureza decorrente da adição de 4%Ag na liga Al-4%Cu solidificada unidirecionalmente

An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

Effects of cellular growth on fatigue life of directionally solidified hypoeutectic Al-Fe Alloys

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