Deformation in the γ-Mg17Al12 phase at 25–278 °C

Mathur, Harshal N.; Maier–Kiener, Verena; Korte‐Kerzel, Sandra

doi:10.1016/j.actamat.2016.05.001

Cited by 60 publications

(24 citation statements)

References 30 publications

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“…The much higher hardness of the intermetallic phase is also evidenced by its brittle behavior at room temperature, where fracture becomes dominant in macroscopic mechanical testing [51,[76][77][78]. This is consistent with the tetrahedral packing leading to corrugated crystallographic planes in Mg 17 Al 12 and the correspondingly large perfect Burgers vector expected on these planes which lead to limited thermal activation of dislocation glide, as found in hardness measurements between room temperature and 0.54 T m [73]. Although Xiao et al [50] suggested a specific (1 1 0) slip plane and microcompression experiments have confirmed slip traces consistent with this type of plane [79], the actual Burgers vector, including that of any partial dislocations and the exact slip planes of Mg 17 Al 12 have, however, not yet been unambiguously identified.…”

Section: Discussionsupporting

confidence: 70%

“…This is consistent with the higher stress required to move dislocations in the complex intermetallic phase Mg 17 Al 12 compared with the pure metallic Mg matrix. At room temperature, the hardness of Mg 17 Al 12 has been measured as 2 GPa and 3.5 GPa in micro-and nano-hardness measurements, respectively [73,74]. In contrast, the micro-hardness of pure magnesium has been measured to 0.34 GPa [75].…”

Section: Discussionmentioning

confidence: 99%

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Atomistic simulations of basal dislocations in Mg interacting with Mg17Al12 precipitates

et al. 2019

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The mechanical properties of Mg-Al alloys are greatly influenced by the complex intermetallic phase Mg 17 Al 12 , which is the most dominant precipitate found in this alloy system. The interaction of basal edge and 30 o dislocations with Mg 17 Al 12 precipitates is studied by molecular dynamics and statics simulations, varying the inter-precipitate spacing (L), and size (D), shape and orientation of the precipitates. The critical resolved shear stress τ c to pass an array of precipitates follows the usual ln(( 1 /D + 1 /L) −1 ) proportionality. In all cases but the smallest precipitate, the dislocations pass the obstacles by depositing dislocation segments in the disordered interphase boundary rather than shearing the precipitate or leaving Orowan loops in the matrix around the precipitate. An absorbed dislocation increases the stress necessary for a second dislocation to pass the precipitate also by absorbing dislocation segments into the boundary. Replacing the precipitate with a void of identical size and shape decreases the critical passing stress and work hardening contribution while an artificially impenetrable Mg 17 Al 12 precipitate increases both. These insights will help improve mesoscale models of hardening by incoherent particles.

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Atomistic simulations of basal dislocations in Mg interacting with Mg17Al12 precipitates

et al. 2019

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“…However, the high temperature mechanical properties of Mg-Al alloys are poor, mainly because of the presence of Mg17Al12 as intermetallic precipitate phase in the microstructure. Mg17Al12 has a low thermal stability and readily softens at temperatures above 130 °C [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Strain heterogeneity and micro-damage nucleation under tensile stresses in an Mg–5Al–3Ca alloy with an intermetallic skeleton

Zubair

Sandlöbes-Haut

Wollenweber

et al. 2019

Materials Science and Engineering: A

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Strain heterogeneity at the microstructural level plays a vital role in the deformation and fracture behaviour of dual or multi-phase materials. In the present work, the strain heterogeneity, localization and partitioning arising at the sub-micron scale during elevated temperature (170 °C) tensile deformation of an Mg-5Al-3Ca alloy was investigated using quasi in-situ μ-DIC experiments. The results reveal that the strain is mainly carried by the α-Mg phase, while the intermetallic Laves phase plays a critical role in that strain concentrations build up at the α-Mg matrix and Laves phase interfaces, hence, reducing the overall deformability of the alloy. In quasi in-situ and bulk material analysis at elevated temperature, cracks were observed to nucleate in the Laves phase, at i) the intersection points of slip lines in the α-Mg matrix with the Laves phase and ii) the twin intersections with α-Mg/Laves phase interfaces and iii) twin transmissions across α-Mg/Laves phase interfaces. Euler number analysis has shown that the (inter-)connectivity of the Laves phase decreases with deformation. Finally, cracks grow preferentially along the Laves phases until the material fractures.

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“…From Figure b, the chemical composition of particle A is Mg–38.39 at% Al–2.68 at% Zn, corresponding to that of β ‐Mg 17 Al 12 . It has been determined that Mg 17 Al 12 phase has a body‐centered cubic (bcc) crystal structure with a lattice parameter of 1.056 nm. The SAED patterns shown in Figure c and d further confirm particle A as Mg 17 Al 12 phase.…”

Section: Resultsmentioning

confidence: 99%

“…β ‐phase usually acts as the major strengthening phase by resisting dislocation shearing and the amount of β ‐phase increases with the increase of the Al addition . In addition, β ‐phase is not thermally stable which will be softening and deformable at temperatures above 150 °C . On the other hand, it seems that the effect of extrusion technology on the mechanical properties of Mg alloys has not been sufficiently investigated.…”

Section: Introductionmentioning

confidence: 99%

Super‐High Strength Mg–7.5Al–0.8Zn Alloy Prepared by Rapidly Solidified Powder Metallurgy and Low Temperature Extrusion

et al. 2017

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In this work, Mg-7.5Al-0.8Zn alloy with super-high tensile strength are fabricated by rapidly solidified powder metallurgy (RS/PM) and low temperature extrusion technology. By reducing extrusion temperature from 340 to 170 C, the α-Mg grains are significantly refined and numerous nanoscale β-Mg 17 Al 12 particles are obtained. The RS/PM alloy extruded at 170 C possesses the lowest grain size of %550 nm. The nanoscale β-phase particles stimulate the nucleation of dynamically recrystallized (DRXed) grains and restrain the growth of DRXed grains. The RS/PM alloy extruded at 170 C exhibits mechanical properties with a tensile yield strength of 448 MPa, an ultimate tensile strength of 480 Mpa, and a microhardness of 137 HV. These excellent mechanical properties result from low temperature extrusion are mainly attributed to the ultra-fine DRXed grains and the high-density dislocations and subgrains.

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Deformation in the γ-Mg17Al12 phase at 25–278 °C

Cited by 60 publications

References 30 publications

Atomistic simulations of basal dislocations in Mg interacting with Mg17Al12 precipitates

Atomistic simulations of basal dislocations in Mg interacting with Mg17Al12 precipitates

Strain heterogeneity and micro-damage nucleation under tensile stresses in an Mg–5Al–3Ca alloy with an intermetallic skeleton

Super‐High Strength Mg–7.5Al–0.8Zn Alloy Prepared by Rapidly Solidified Powder Metallurgy and Low Temperature Extrusion

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