Single-crystal growth of the complex metallic alloy phase β-Al–Mg

Lipińska-Chwałek, Marta; Balanetskyy, S.; Thomas, C.; Roitsch, Stefan; Feuerbacher, M.

doi:10.1016/j.intermet.2007.07.006

Cited by 12 publications

(7 citation statements)

References 14 publications

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“…This may be due to the fact that the Czochralski crystal is grown seeded and is unconstrained during cooling. Similar observations were made for other CMA phases [9,10].…”

Section: Discussionsupporting

confidence: 88%

“…In recent years, single-crystal growth routes for CMA materials were developed for a few systems. Single crystals of x 0 -Al-Pd-Mn, an orthorhombic phase with about 320 atoms per unit cell [9] and b-Al 3 Mg 2 , a cubic phase with 1168 atoms per cell [10] were successfully produced, which has triggered considerable experimental activity. In the present paper we describe, for the first time, the development of a growth route for the CMA phase Mg 32 (Al,Zn) 49 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Single-crystal growth of the complex metallic alloy phase Mg32(Al,Zn)49

Feuerbacher¹,

Thomas²,

Roitsch³

2008

Intermetallics

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“…This may be due to the fact that the Czochralski crystal is grown seeded and is unconstrained during cooling. Similar observations were made for other CMA phases [9,10].…”

Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Single-crystal growth of the complex metallic alloy phase Mg32(Al,Zn)49

Feuerbacher¹,

Thomas²,

Roitsch³

2008

Intermetallics

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“…Single-phased polycrystalline samples (*3 9 2 9 2 mm 3 ) of initial homogeneous grain size of about 20 lm were cut from an ingot with composition Al 61.5 Mg 38.5 whose synthesis has been described in detail elsewhere [17,18]. Briefly, elemental Al and Mg with a purity of 99.999% for Al and 99.98% for Mg were used as starting materials.…”

Section: Al 3 Mg 2 Sample Synthesismentioning

confidence: 99%

“…The present paper forms part of a detailed investigation of Al 3 Mg 2 which was undertaken within the European Network of Excellence on Complex Metallic Alloys (NoE CMA) and included the development of growth routes for singlecrystals and single-phase polycrystals of the b-phase, as well as comprehensive measurements of some basic physical and chemical properties such as thermal expansion, elasticity, magnetic properties, transport properties, superconductivity, corrosion and tribocorrosion resistance [17][18][19][20][21]. In this study, thermogravimetry was used to follow the oxidation kinetics of bulk and powder single-phased b-Al 3 Mg 2 samples in the temperature range of 350-420°C (the melting point of b-Al 3 Mg 2 is 452°C) whereas the chemical nature and the structure of the oxide scale were characterised using electron microscopies (SEM and TEM).…”

Section: Introductionmentioning

confidence: 99%

High Temperature Oxidation of the Al3Mg2 Complex Metallic Alloy

et al. 2009

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International audienceHigh temperature air oxidation of the Al3Mg2 complex metallic alloy was investigated on powder samples and bulk polycrystals in the temperature range 350–420 °C by thermogravimetric measurements, SEM and TEM. Oxidation at 420 °C on the polycrystalline samples comprised three successive phases characterised by linear kinetics laws. The first stage corresponded to the formation of a porous non adherent nanocrystalline MgO scale having a cauliflower morphology. A first acceleration in the kinetics law was ascribed to the nucleation and growth of MgAl2O4 crystallites which form a thin (~10 nm) film at the interface between the substrate alloy and the MgO top layer. A new linear regime was observed in the oxidation process corresponding to diffusion of magnesium through the grain boundaries of the spinel film and through the porous MgO layer. Finally, fragmentation and cracking of the scale leads to a further acceleration followed by a new linear regime

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“…The complex structure of β (Al3Mg2: unit cell of 1168 atoms [92,94] Several micromechanical models predicted the elevation of tensile and hydrostatic stresses adjacent to a non-deformable spherical particle, and within a layer of deformable phase constrained by an elastic boundary condition provided by adjacent non-deformable particles. These models are specific to global-uniaxial deformation and have not been extended to a crack tip.…”

Section: The Role Of β In Developing Crack Tip Chemistrymentioning

confidence: 99%

Validation of the Coupled Dissolution-Hydrogen Embrittlement Mechanism of IGSCC in Low Temperature Sensitized AA5083-H131

Crane¹

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Non-heat-treatable wrought Al-Mg alloys are commonly used in marine structures that require light weight, moderate strength, weldability, and corrosion resistance. These alloys become susceptible to intergranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) when an active β phase (Al3Mg2) precipitates on grain boundaries during prolonged thermal exposure. The Degree of Sensitization (DoS) is quantified using the standard nitric acid mass loss test. Coupled dissolution of β and H embrittlement is the hypothesized mechanism of IGSCC in sensitized Al-Mg. The primary objectives of this research are to characterize the interactive crack tip electrochemical and mechanical factors that govern IGSCC in Al-Mg alloy 5083-H131, and particularly to test this hypothesized mechanism. Research is focused on low temperature, long time sensitization with discrete grain boundary β precipitation. High resolution subcritical crack growth experiments established a critical DoS of about 10 mg/cm 2 for IGSCC susceptibility in 5083-H131 stressed at near open circuit potential in neutral NaCl. Below this DoS, the alloy is essentially immune to IGSCC, while above this sensitization, crack growth rates increase as a unique function of DoS for several time-temperature conditions. This threshold is likely due to an acidic crack tip chemistry established by the dissolution of a critical volume of β, in combination with an increase in local stress for increased H concentration ahead of the crack tip due to β presence. As β volume increases and spacing decreases, these factors continue to increase crack growth rates. Crack growth measurements and elastic-plastic Jintegral analysis establish that this alloy is susceptible to H embrittlement in the absence of β phase, provided that an acidic chemistry is artificially generated in the crack tip, as an analog to β dissolution. The role of β is verified using polarization to either promote or preclude β dissolution. Anodic polarization significantly enhances crack growth, while cathodic polarization suppresses IGSCC because both β and matrix dissolution are limited. Results demonstrate the strong benefit of modest cathodic polarization as a means to control IGSCC. The role of H is separated from β dissolution through hydrogen precharging of tensile specimens stressed in the absence of a β-dissolving crack tip electrolyte. Results demonstrate that, though β is not essential for hydrogen environment embrittlement, β presence promotes H damage. The coupled dissolution H-embrittlement mechanism for IGSCC in 5083-H131 is validated by demonstrating that: a) β distribution controls crack tip chemistry and H localization at the fracture process zone, b) crack tip electrochemistry provides the H production and uptake for grain boundary decohesion, and c) H-diffusion, rate-limited embrittlement is the dominant mechanism for crack growth between β. Unexpectedly rapid IGSCC rates can be explained based on enhanced H diffusion in this ligament as trapping impedance is reduced. The...

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Single-crystal growth of the complex metallic alloy phase β-Al–Mg

Cited by 12 publications

References 14 publications

Single-crystal growth of the complex metallic alloy phase Mg32(Al,Zn)49

Single-crystal growth of the complex metallic alloy phase Mg32(Al,Zn)49

High Temperature Oxidation of the Al3Mg2 Complex Metallic Alloy

Validation of the Coupled Dissolution-Hydrogen Embrittlement Mechanism of IGSCC in Low Temperature Sensitized AA5083-H131

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