Comparative Evaluation of Cast Aluminum Alloys for Automotive Cylinder Heads: Part I—Microstructure Evolution

Roy, Shibayan; Allard, Lawrence F.; Rodrı́guez, A.; Watkins, Thomas R.; Shyam, Amit

doi:10.1007/s11661-017-3985-1

Cited by 56 publications

(8 citation statements)

References 68 publications

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“…3)). Limited traces of elongated Fe-rich intermetallics were also identified in the as-cast microstructures of all alloys, known as Al 7 Cu 2 Fe [33].…”

Section: Alloysmentioning

confidence: 99%

Optimisation of heat treatment of Al–Cu–(Mg–Ag) cast alloys

Zamani

Toschi

Morri

et al. 2019

J Therm Anal Calorim

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The optimisation of heat treatment parameters for Al-Cu-(Mg-Ag) cast alloys (2xxx) having different microstructural scales was investigated. Thermo-Calc software was used to design optimal alloy compositions. Differential scanning calorimetry (DSC), scanning electron microscopy and wavelength-dispersive spectroscopy technique were employed to determine proper solution heat treatment temperature and homogenisation time as well as incidence of incipient melting. Proper artificial ageing temperature for each alloy was identified using DSC analysis and hardness measurement. Microstructural scale had a pronounced influence on time and temperature required for complete dissolution of Al 2 Cu and homogenisation of Cu solute atoms in the a-Al matrix. Refined microstructure required only one-step solution treatment and relatively short solution treatment of 10 h to achieve dissolution and homogenisation, while coarser microstructures desired longer time. Addition of Mg to Al-Cu alloys promoted the formation of phases having a rather low melting temperature which demands multi-step solution treatment. Presence of Ag decreases the melting temperature of intermetallics (beside Al 2 Cu) and improvement in age-hardening response. Peak-aged temperature is primarily affected by the chemical composition rather than the microstructural scale.

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“…3)). Limited traces of elongated Fe-rich intermetallics were also identified in the as-cast microstructures of all alloys, known as Al 7 Cu 2 Fe [33].…”

Section: Alloysmentioning

confidence: 99%

Optimisation of heat treatment of Al–Cu–(Mg–Ag) cast alloys

Zamani

Toschi

Morri

et al. 2019

J Therm Anal Calorim

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“…The alloy is classically solution heat treated (SHT) at about 540 • C [4] with multiple effects of homogenizing the alloy compositions, reducing the amount of coarse embrittling phases, bringing precipitates in solid solution and concurrently modifying silicon morphology. An artificial aging at temperatures 155-200 • C follows [3], during which the β-Mg2Si precipitation sequence evolves similarly to what observed in wrought Al-Mg-Si alloys, where also the Si or U2-Mg-Al-Si phase can be observed substituting β" in alloys with high Si content [5,6].…”

Section: Introductionmentioning

confidence: 74%

“…A356 (Al-7Si-0.4Mg) is a casting alloy widely applied in automotive and aeronautical fields, as referred by Mishra et al [1] and Jeong et al [2], among others. The casting alloy is age-hardenable, and, thus, its mechanical properties depend on the combination of several microstructural features, from macroscopic and microscopic ones (including dendrite arm spacing, grain size, coarse equilibrium or non-equilibrium intermetallic phases, porosities and other possible discontinuities related to casting processes) down to the presence of nanometric precipitates with noticeable strengthening effect [3,4]. The alloy is classically solution heat treated (SHT) at about 540 • C [4] with multiple effects of homogenizing the alloy compositions, reducing the amount of coarse embrittling phases, bringing precipitates in solid solution and concurrently modifying silicon morphology.…”

Section: Introductionmentioning

confidence: 99%

High Temperature Behavior of Al-7Si-0.4Mg Alloy with Er and Zr Additions

Gariboldi

Confalonieri

Colombo

2021

Metals

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In recent years, many efforts have been devoted to the development of innovative Al-based casting alloys with improved high temperature strength. Research is often oriented to the investigation of the effects of minor element additions to widely diffused casting alloys. The present study focuses on Al-7Si-0.4Mg (A356) alloy with small additions of Er and Zr. Following previous scientific works on the optimization of heat treatment and on tensile strength, creep tests were carried out at 300 °C under applied stress of 30 MPa, a reference condition for creep characterization of innovative high-temperature Al alloys. The alloys containing both Er and Zr displayed a lower minimum creep strain rate and a longer time to rupture. Fractographic and microstructural analyses on crept and aged specimens were performed to understand the role played by eutectic silicon, by the coarse intermetallics and by α-Al matrix ductility. The creep behavior in tension of the three alloys has been discussed by comparing them to tension and compression creep curves available in the literature for Al-7Si-0.4Mg improved by minor elemental additions.

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“…For small grains, the PFZ would extend over a significant fraction of the The SEM micrographs ( Figure 2) reveal the variation in the morphology and density of the intermetallic particles, which appear in brighter contrast than the primary phases in the SEM micrographs. These particles are likely the primary eutectic θ (Al 2 Cu) phase [39]. In the non-grain-refined alloy, these θ particles appear both at the grain boundaries and on cellular boundaries within the grain bulk.…”

Section: Microstructure Characterization For the Da2 Alloymentioning

confidence: 98%

Grain Refinement Effect on the Hot-Tearing Resistance of Higher-Temperature Al–Cu–Mn–Zr Alloys

Sabau

Milligan

Mirmiran

et al. 2020

Metals

Self Cite

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The hot-tearing resistance of Al-Cu-Mn-Zr (ACMZ) alloys was investigated as a steptoward introducing these new cast alloys for severe duty, higher-temperature applications, such ascylinder heads for down-sized, turbocharged automotive engines. Alloy Cu compositions werevaried from 5 to 8 wt.%. Targeted Ti levels were 0.02, 0.1, and 0.2 wt.% via additions of the Al–5Ti–1B master alloy. Hot-tearing resistance was assessed by visual examination and ranking of thecracking severity in a multi-arm permanent mold casting. It was found that at high impuritycontents (Fe and Si of 0.2 wt.% each), the Al–Cu–Mn–Zr alloy with 4.95 wt.% Cu exhibited thepoorest hot-tearing resistance, irrespective of the grain refining amount. Microstructural analysisindicated an effective reduction in the grain size, as the Ti additions were increased to 0.02 and 0.1wt.% Ti via the Al–Ti–B grain refiner. The finest grain size was attained with a 0.1 wt.% Ti. Basedon the hot-tearing evaluation, it was found that the additional grain refining via the Al–5Ti–1Bmaster alloy at 0.1 wt.% Ti significantly reduces the hot-tearing susceptibility at Cu contents greaterthan 7.3 wt.% for ACMZ alloys with low Fe and Si. These findings indicate that the best hot-tearingresistance was observed at a grain refiner level of 0.1 wt.% Ti and high Cu content (greater than 7.3wt.%). This study to indicates that these Al–Cu–Mn–Zr alloys, which possess excellentmicrostructural stability and mechanical properties at elevated temperatures, can also possessexcellent hot-tearing resistance.

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Comparative Evaluation of Cast Aluminum Alloys for Automotive Cylinder Heads: Part I—Microstructure Evolution

Cited by 56 publications

References 68 publications

Optimisation of heat treatment of Al–Cu–(Mg–Ag) cast alloys

Optimisation of heat treatment of Al–Cu–(Mg–Ag) cast alloys

High Temperature Behavior of Al-7Si-0.4Mg Alloy with Er and Zr Additions

Grain Refinement Effect on the Hot-Tearing Resistance of Higher-Temperature Al–Cu–Mn–Zr Alloys

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