Origins and dissociation of pyramidal &lt;c + a&gt; dislocations in magnesium and its alloys

Ding, Zhigang; Liu, Wei; Sun, Hao; Li, Shuang; Zhang, Dalong; Zhao, Yonghao; Lavernia, Enrique J.; Zhu, Yuntian

doi:10.1016/j.actamat.2017.12.049

Cited by 88 publications

(18 citation statements)

References 60 publications

(119 reference statements)

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“…The values for the GSFE0.3b, GSFE0.4b and GSFE0.7b are 175, 165 and 318 mJ m −2 , respectively. The positions and values coincide with the data calculated with the same relaxing procedures (174, 163 and 315 mJ m −2 for GSFE0.3b, GSFE0.4b and GSFE0.7b, respectively) [23]. In that work, the van der Waals forces were calculated as well.…”

Section: Resultssupporting

confidence: 75%

“… a Reference [23], the van der Waals forces were calculated; b Reference [19], the van der Waals forces were not calculated; c Reference [23], the van der Waals forces were calculated. In this reference, the alloy is Mg47Y1 but the solute concentration on the doped plane is equal to the present work.…”

Section: Figurementioning

confidence: 99%

“…Ding et al investigated the effects of Y on the generalized stacking fault energies (GSFEs) of the {10-11}<11-23> slip system [23]. The results illustrated that the stable SFE disappeared in the MgY alloy.…”

Section: Introductionmentioning

confidence: 99%

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Generalized Stacking Fault Energy of {10-11}<11-23> Slip System in Mg-Based Binary Alloys: A First Principles Study

Dou

Luo

2019

Materials

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In this work, the generalized stacking fault energies (GSFEs) of {10-11}<11-23> slip system in a wide range of Mg-X (X = Ag, Al, Bi, Ca, Dy, Er, Gd, Ho, Li, Lu, Mn, Nd, Pb, Sc, Sm, Sn, Y, Yb, Zn and Zr) binary alloys has been studied. The doping concentration in the doping plane and the Mg-X system is 12.5 at.% and 1.79 at.%, respectively. Two slip modes (slip mode I and II) were considered. For pure magnesium, these two slip modes are equivalent to each other. However, substituting a solute atom into the magnesium matrix will cause different effects on these two slip modes. Based on the calculated GSFEs, two design maps were constructed to predict solute effects on the behavior of the {10-11}<11-23> dislocations. The design maps suggest that the addition of Ag, Al, Ca, Dy, Er, Gd, Ho, Lu, Nd, Sm, Y, Yb and Zn could facilitate the {10-11}<11-23> dislocations.

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Section: Resultssupporting

confidence: 75%

Section: Figurementioning

confidence: 99%

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Generalized Stacking Fault Energy of {10-11}<11-23> Slip System in Mg-Based Binary Alloys: A First Principles Study

Dou

Luo

2019

Materials

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“…Magnesium and its alloys meet the needs of high efficiency and sustainable development. Magnesium alloy, as one of the advanced metal materials, is widely used in aerospace, automobile manufacturing, biomedicine, and other industries due to its advantages of high specific strength and light weight [1][2][3]. Additionally, there is the potential and possibility to replace aluminum and steel in many structural applications [4].…”

Section: Introductionmentioning

confidence: 99%

Balling Behavior of Selective Laser Melting (SLM) Magnesium Alloy

Liu

Guo

2020

Materials

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Macroscopic surface morphology and balling mechanism of AZ61 magnesium alloy prepared by Selective laser melting (SLM) have been investigated. This article studied and analyzed the surface morphology and balling phenomenon of Mg in the laser processing from the aspects of Mg inherent metal properties and laser processing. In terms of laser processing, the results show that, in the direction of increasing scanning speed, the energy density decreases, and the phenomenon of balling and porosity on the surface of the magnesium alloy is serious. When the energy density is 133.9–187.5 J/mm3, balling particles are significantly reduced. It can be seen from the low-magnification SEM image that, even at a scanning speed of 250 mm/s (Ev is 187.5 J/mm3), there are still a few small-sized balling particles on the surface. Therefore, in terms of inherent metal properties, the wettability, capillary instability, thermodynamic, and kinetic analysis of the balling behavior of Mg and other metal (Al, Fe, Cu, Ni, Ti) droplets in the SLM process has been carried out, and the dynamic model of magnesium droplet spreading/solidification was established basic on the result of experiment and metal inherent properties. The results show that SLMed magnesium alloy is a competitive process of melt diffusion and solidification. The final result depends on the intrinsic properties of the magnesium alloy and the applied laser processing parameters. The spreading process of Mg melt is very fast. Although the solidification time of Mg melts changes slowly with the increase of metal droplet temperature, the spreading speed is still very fast due to the low melt density, so the balling phenomenon of SLMed Mg can be controlled to a certain extent. Theoretically calculated, the solidification time of Mg melt droplet is longer than the wetting time at 1173 K (900 °C), so the spreading process is dominant, which can minimize the balling and realize the densification of SLMed Mg. The dynamic spreading of molten pool, the analysis of wetting and solidification process, and the establishment of SLM balling model can provide reference for the design of the SLM forming parameters of Mg and other different metals.

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“…In light of this generally accepted understanding, proposed alloy design strategies primarily stabilize the hc þ ai dislocation and prevent the glissile-to-sessile transformation (11). The glissile-to-sessile transformation is not observed in some recent simulation studies (12)(13)(14), in which hc þ ai dislocations glide on pyramidal planes, even though the actual slip plane is under debate (15,16). Controversy surrounds the fundamental behavior of hc þ ai dislocations, such as their ability to accommodate plastic strain and their slip pathways.…”

mentioning

confidence: 99%

Large plasticity in magnesium mediated by pyramidal dislocations

Liu

Yang

et al. 2019

Science

303

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Lightweight magnesium alloys are attractive as structural materials for improving energy efficiency in applications such as weight reduction of transportation vehicles. One major obstacle for widespread applications is the limited ductility of magnesium, which has been attributed to 〈c+a〉 dislocations failing to accommodate plastic strain. We demonstrate, using in situ transmission electron microscope mechanical testing, that 〈c+a〉 dislocations of various characters can accommodate considerable plasticity through gliding on pyramidal planes. We found that submicrometer-size magnesium samples exhibit high plasticity that is far greater than for their bulk counterparts. Small crystal size usually brings high stress, which in turn activates more 〈c+a〉 dislocations in magnesium to accommodate plasticity, leading to both high strength and good plasticity.

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Origins and dissociation of pyramidal <c + a> dislocations in magnesium and its alloys

Cited by 88 publications

References 60 publications

Generalized Stacking Fault Energy of {10-11}<11-23> Slip System in Mg-Based Binary Alloys: A First Principles Study

Generalized Stacking Fault Energy of {10-11}<11-23> Slip System in Mg-Based Binary Alloys: A First Principles Study

Balling Behavior of Selective Laser Melting (SLM) Magnesium Alloy

Large plasticity in magnesium mediated by pyramidal dislocations

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