Three-Dimensional Morphology of C15–Al&lt;sub&gt;2&lt;/sub&gt;Ca Precipitates in a Mg–Al–Ca Alloy

Kashiwase, Sakiko; Unekawa, Mariko; Hisazawa, Hiromu; Terada, Yoshihiro

doi:10.2320/matertrans.mt-m2019149

Cited by 12 publications

(4 citation statements)

References 17 publications

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“…Considering comparable texture ( Figure 7 ), these particles compensated for lower strengthening effect of the grain boundaries. Note that the precipitation hardening by Al 2 Ca particles has already been proved in previous reports [ 29 , 30 , 31 ]. The lowest strength measured for the AE42 alloy is because of the combined effect of lack of very small secondary phase particles, which were observed in other investigated alloys ( Figure 2 and Figure 6 ), and the formation of very strong texture component A ( Figure 7 ).…”

Section: Resultssupporting

confidence: 74%

Novel Ultrafine-Grain Mg-Gd/Nd-Y-Ca Alloys with an Increased Ignition Temperature

et al. 2023

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Two novel ignition-resistant magnesium alloys, Mg-2Gd-2Y-1Ca and Mg-2Nd-1Y-1Ca, were prepared in the ultrafine-grain condition by equal channel angular pressing (ECAP). In addition, four commercial alloys—AZ31, AX41, AE42 and WE43—were prepared similarly as a reference. The microstructure, mechanical properties and ignition temperature were thoroughly investigated. Both novel alloys exhibited a mean grain size of ~1 µm and dense distribution of small secondary phase particles. The mechanical strength measured by the tensile deformation test showed that the novel alloys are much stronger (~290 MPa) than all commercial alloys except WE43. However, Ca segregation into the grain boundaries caused a significant decrease in ductility (<6%). The ignition temperature of the novel alloys (~950 °C) was considerably improved by the presence of Gd/Nd, Y and Ca. This study showed that both novel alloys exhibit high strength and high ignition temperature in the ultrafine-grain condition.

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Section: Resultssupporting

confidence: 74%

Novel Ultrafine-Grain Mg-Gd/Nd-Y-Ca Alloys with an Increased Ignition Temperature

et al. 2023

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“…Kashiwase et al reported that C15 precipitates have a hexagonal plate-like morphology; their planar surface is parallel to the (0001) basal plane, while the sides of the hexagonal plate are parallel to the f11 20g second columnar plane of the ¡-Mg matrix. 47) When the alloy was aged at 523 K for 100 h, the Al 2 Ca precipitate showed a thickness, equal to six layers of the (111) C15 plane composed of Ca atoms, of approximately 1.5 nm.…”

Section: C15-al 2 Ca Phasementioning

confidence: 99%

Creep of a Die-Cast Mg–5Al–2Ca Alloy: An Overview

Terada

2023

Mater. Trans.

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A comprehensive research program on the creep of a die-cast Mg-5Al-2Ca (mass%) alloy, which has been conducted in the last two decades by our group, is overviewed. The obtained results are summarized into the following categories: microstructure and creep strength, creep parameters, dislocation analysis, and life assessment. The creep strength of the alloy is predominantly ascribed to the interconnected skeleton of C36-(Mg,Al) 2 Ca phase, while the fine C15-Al 2 Ca precipitates have limited effects on creep strength. The change in creep parameters, n and Q c , results from the decreased creep strength driven by the divorce of the interconnected skeleton of C36 phase during creep. At stress levels below the yield stress, the dislocation climb in the primary ¡-Mg grains is inferred as the rate-controlling process for the alloy. Mostly ©aª type dislocations are introduced within the primary ¡-Mg grains during die-casting, and the dislocation segments are mainly located on the basal plane. The basal segments of dislocations bow out and glide on the basal planes under stress, and the jogs follow the basal segments with the help of climb during creep. The minimum creep rate and creep rupture life follow the phenomenological Monkman-Grant relationship for the alloy. When the Larson-Miller constant is set at 20, the value of Larson-Miller parameter is uniquely described by the logarithm of the applied stress.

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“…Moreover, the sides of the hexagonal plate are parallel to the {11-20} ¡ second columnar plane of the ¡ matrix. 8) Precipitation of the Mg 2 Ca phase has been observed in binary MgCa alloys, but very little is known about the three-dimensional morphology of these precipitates. 9,10) Therefore, the aim of this study is to clarify the morphological evolution of Mg 2 Ca precipitates and the coherence between these precipitates and the ¡-Mg matrix.…”

Section: Introductionmentioning

confidence: 99%

HRTEM Characterization of an Age-Hardened Mg–Ca Binary Alloy

Unekawa

Terada

2023

Mater. Trans.

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A Mg2.8 mass% Ca binary alloy was subjected to a homogenization treatment. The three-dimensional morphology and coherency of the Mg 2 Ca phase (with C14 structure), which precipitated in the primary ¡-Mg dendrite, were investigated for the specimens aged at 423 K. The Mg 2 Ca precipitate exhibited a hexagonal plate-like morphology, with a planar surface that is parallel to the (0001) ¡ basal plane and sides that are parallel to the {-1010} ¡ columnar plane of the ¡-Mg matrix. The coarsening Mg 2 Ca precipitate retained coherency with the ¡-Mg matrix for aging time of 3 h, which corresponded to the peak-aged condition. Furthermore, during the coarsening process, misfit dislocations were introduced on the planar surface of the precipitates, and the coherent interface became a semi-coherent interface for aging time of 100 h, which corresponded to the over-aged condition. The Mg 2 Ca precipitates evolved from a hexagonal plate-like morphology to a rectangular morphology and then to a polygonal morphology during aging treatment at 423 K.

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Three-Dimensional Morphology of C15–Al<sub>2</sub>Ca Precipitates in a Mg–Al–Ca Alloy

Cited by 12 publications

References 17 publications

Novel Ultrafine-Grain Mg-Gd/Nd-Y-Ca Alloys with an Increased Ignition Temperature

Novel Ultrafine-Grain Mg-Gd/Nd-Y-Ca Alloys with an Increased Ignition Temperature

Creep of a Die-Cast Mg–5Al–2Ca Alloy: An Overview

HRTEM Characterization of an Age-Hardened Mg–Ca Binary Alloy

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