Crystallization behavior of iron-containing intermetallic compounds in 319 aluminum alloy

Narayanan, L. Anantha; Samuel, F. H.; Gruzleski, J. E.

doi:10.1007/bf02668540

Cited by 276 publications

(174 citation statements)

References 5 publications

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“…The size and number density of b platelets depend on the chemical composition of the alloy, solidification conditions, etc., and earlier studies provide examples of b with sizes of 10, [38] 15, [39] 75, [34] 150, [33] 250, [26,27] 400, [15] 500, [16] 1000, [19] and 5-250 [30] lm. In the current study, the largest observed platelet was 1300-lm long, which means that X-ray tomography is more efficient at showing the real sizes of b compared to 2D microsections.…”

Section: D Morphology Of Fe-rich Phasesmentioning

confidence: 79%

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Mikołajczak

Ratke

2014

Metall Mater Trans A

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The presence of Fe aids in establishing the mechanical and physical properties of AlSi alloys and is also one of the main impurities leading to formation of b-Al 5 FeSi intermetallics. This study aims to understand the effect of fluid flow on the dendritic microstructure with intermetallics in Al-5/7/9 wt pct Si-0.2/0.5/1.0 wt pct Fe alloys that are directionally solidified under defined thermal and fluid flow conditions. We made extensive use of 3D X-ray tomography to obtain a better insight into the morphology and formation of the intermetallics. Three-dimensional (3-D) distribution of intermetallics presented here shows that the growth of large b-Al 5 FeSi due to forced flow occurs in the eutectic specimen center and together with an increase in the number density of b precipitates. The 3D reconstructions have verified the b shaped to be curved, bent with twining, branched, and to have imprints, holes, and propeller-shaped platelets. The 3D views showed that hole-shaped b arose from the lateral growth around a-Al dendrites. These views also confirmed the phenomenon of shortening of b as an effect of flow in the dendritic region, where b could be fragmented or completely remelted, and ultimately resulting in microstructures with shorter b-Al 5 FeSi and increases in number density. The analysis revealed an interaction between melt flow, 3D distribution, and the morphology of b-Al 5 FeSi. The growth of a large and complex group of b intermetallics can reduce the melt flow between dendrites and strengthen pore nucleation and eutectic colonies nucleation, leading to lower permeability of the mushy zone and increased porosity in the castings.

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Section: D Morphology Of Fe-rich Phasesmentioning

confidence: 79%

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Mikołajczak

Ratke

2014

Metall Mater Trans A

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“…Cu increases the age hardening precipitation of Al 2 Cu as well as that of Mg 2 Si for Mg, and Mn is an element in Al 15 (Mn,Fe) 3 Si 2 intermetallic particle formation. 14,15) Therefore, these elements result in an increase in the elastic modulus at a given temperature. The next chapter discusses the high temperature stability of particles with elements.…”

Section: (B)mentioning

confidence: 99%

High Temperature Mechanical Properties of Al–Si–Mg–(Cu) Alloys for Automotive Cylinder Heads

Jeong

2013

Mater. Trans.

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To improve the fuel efficiency and reduce automobile emissions, there has been growing demand of more durable alloys for engine components with the improved thermal and fatigue resistance. This study examined the effect of alloying elements on the high mechanical behavior of AlSiMg(Cu) casting alloys for cylinder heads. Depending on the alloying elements affecting the strength of the matrix, the thermal expansion coefficient decreased with increasing Mn and Cu content at high temperatures with a concomitant increase in the elastic modulus, hardness and tensile strength. Quantatative analysis showed that the mechanical properties of the Al 2 Cu precipitate hardened alloy were maintained at temperatures over 250°C, whereas the degradation of mechanical properties of the Mg containing alloy occurred at 170°C due to coarsening of the Mg 2 Si precipitation phase. The LCF (low cycle fatigue) lives decreased with increasing alloy content according to the Coffin-Manson relation due to the smaller elongation. On the other hand, an analysis of the fatigue lives with the hysteresis loop energy, which consists of both strength and elongation, showed that the fatigue lives were normalized with an alloy of the same strengthening mechanisms regardless of the test temperature.

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“…Fe and Cu, which have relatively high temperature stabilities compared to Mg, restrict thermal expansion and increase the stiffness. Cu increases the age hardening precipitation of Al 2 Cu as well as that of Mg 2 Si for Mg, and Fe is an element in the intermetallic particle formation of Al 5 FeSi 18,19) . Therefore, the coarse and non-uniformly distributed particles with larger DAS result in a decrease in the elastic modulus at a given temperature.…”

Section: Methodsmentioning

confidence: 99%

Effect of Microstructure on High Temperature Mechanical Properties of A319 Casting Alloy for Automotive Cylinder Heads

Kim

Jeong

2016

Mater. Trans.

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A quantitative study has been conducted to evaluate the relationship between microstructural features such as secondary DAS (dendrite arm spacing), eutectic structures and the mechanical behaviors of A319 casting alloys. Depending on the cooling rate affecting the primary and eutectic microstructure, the storage elastic modulus measured by DMA (dynamic mechanical analysis) increased with decreasing DAS, with a concomitant increase in the tensile strength and elongation at RT and also high tempertures. Contrarily, the thermal expansion coef cient increased with increasing temperature, but did not vary with microstructural changes. The hardness of the eutectic phase increased with increasing DAS due to the enlarged size of the eutectic particles, whereas the hardness of the primary phase was similar regardless of DAS, owing to the precipitates that formed during heat treatment. The increase of both of LCF (low cycle fatigue) and HCF (high cycle fatigue) lives with decreasing DAS was observed, mainly due to homogeneous deformation owing to the ne size of eutectic silicon and Fe intermetallic particles. The results of fractography observation showed that ner α-Al and eutectic phases were effective to the resistance of fatigue crack initiation and propagation due to the shorter crack path along the secondary particles. The LCF lives increased with increasing test temperature according to the Cof n-Manson relation due to the larger elongation. On the other hand, an analysis of the fatigue lives with the hysteresis loop energy, which consists of both strength and elongation, showed that the fatigue lives were normalized with an alloy of the same strengthening mechanisms regardless of the test temperature. DMA analysis demonstrated that the mechanical properties of the Al 2 Cu precipitate hardened alloy were maintained at temperatures greater than 250 C, whereas degradation in the mechanical properties of the Mg-containing alloy occurred at 170 C due to coarsening in the precipitation phase of Mg 2 Si.

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Crystallization behavior of iron-containing intermetallic compounds in 319 aluminum alloy

Cited by 276 publications

References 5 publications

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

High Temperature Mechanical Properties of Al–Si–Mg–(Cu) Alloys for Automotive Cylinder Heads

Effect of Microstructure on High Temperature Mechanical Properties of A319 Casting Alloy for Automotive Cylinder Heads

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Crystallization behavior of iron-containing intermetallic compounds in 319 aluminum alloy

Cited by 276 publications

References 5 publications

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

High Temperature Mechanical Properties of Al&ndash;Si&ndash;Mg&ndash;(Cu) Alloys for Automotive Cylinder Heads

Effect of Microstructure on High Temperature Mechanical Properties of A319 Casting Alloy for Automotive Cylinder Heads

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High Temperature Mechanical Properties of Al–Si–Mg–(Cu) Alloys for Automotive Cylinder Heads