Competitive Heterogeneous Nucleation Between Zr and MgO Particles in Commercial Purity Magnesium

Peng, Guosheng; Wang, Y.; Fan, Z.

doi:10.1007/s11661-018-4594-3

Cited by 28 publications

(25 citation statements)

References 34 publications

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“…The lattice misfit between MgO{1 1 1} and Mg{0 0 0 1} is 8.2 pct. [12,16] However, as shown in the literature, lattice misfit has little influence on the layering of the liquid atoms adjacent to the substrate. [23,24] Therefore, we can conclude that the weakened layering in the L-Mg/MgO{1 1 1} system originates from the atomically rough substrate surface, [26] since the atomically rough surface hinders the templating of substrate for liquid Mg to nucleate, according to the epitaxial nucleation/growth model.…”

Section: B Effects Of the Substrate Surfaces On Prenucleationmentioning

confidence: 88%

“…In light of such understanding of prenucleation, we analyze the nucleation potency of MgO in the L-Mg/ MgO system. The previous study [12,16] showed that MgO{1 1 1} has 8.2 pct lattice misfit with solid Mg, suggesting that MgO{1 1 1} is a poor substrate for prenucleation. The present study has shown that regardless the nature of starting surface termination, MgO{1 1 1} in liquid Mg always has a Mg layer as its new terminating surface that contain significant amount of vacancies (Figure 2), rendering MgO{1 1 1} atomically rough.…”

Section: A Nucleation Potency Of Mgo In Liquid Mgmentioning

confidence: 99%

“…In addition, the L-Mg/MgO{0 0 1} system represents another interesting case for heterogeneous nucleation. Structurally, the MgO{0 0 1} substrate also has a large lattice misfit with a-Mg, [12,16] hindering it for heterogeneous nucleation. Chemically, MgO{0 0 1} surface is non-polar under ambient conditions.…”

Section: A Nucleation Potency Of Mgo In Liquid Mgmentioning

confidence: 99%

“…The free electrons of the liquid metal can eliminate the polar effect and stabilize the polar surfaces, such as in the case of MgO{1 1 1} in liquid Mg. MgO{1 1 1} surfaces have a two dimensional hexagonal lattice, the same as that of the close packed Mg{0 0 0 1} plane. However, there exists a large lattice misfit between MgO{1 1 1} and Mg{0 0 0 1} (8.2 pct), [12,16] rendering MgO particles impotent for heterogeneous nucleation of Mg.…”

Section: Introductionmentioning

confidence: 99%

“…[13,[16][17][18][19][20][21] Native MgO particles in Mg melts have two distinctive morphologies: octahedron with {1 1 1} surface terminations (denoted as MgO{1 1 1}) and cubic with the {0 0 1} surface terminations (denoted as MgO{0 0 1}). [12,13,[16][17][18][19] Experimental investigations by high-resolution transmission electron microscopy (HRTEM) have confirmed that there exist specific orientation relations (ORs) between the MgO substrates and the solid Mg. This suggests that fcc MgO can act as sites for heterogeneous nucleation of hcp a-Mg. First-principles approaches were used to explore mainly the wetting and adhesion for different crystal orientations between solid a-Mg and MgO.…”

Section: Introductionmentioning

confidence: 99%

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Prenucleation at the Interface Between MgO and Liquid Magnesium: An Ab Initio Molecular Dynamics Study

Fang

Fan

2019

Metall Mater Trans A

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Magnesia (MgO) particles inevitably exist in liquid Mg and may be used as potential sites for heterogeneous nucleation to achieve effective grain refinement. Understanding of the atomic configurations on MgO surfaces and in the liquid Mg adjacent to the liquid Mg/MgO interfaces is therefore of both scientific and practical interests. We investigate the surface structures of MgO in liquid Mg and the atomic arrangements of liquid Mg adjacent to liquid/substrate interfaces, using an ab initio molecular dynamics (MD) simulation technique. We find that an atomically rough terminating Mg layer forms on the {1 1 1} terminated MgO substrate (octahedral MgO) in liquid Mg. The simulations also reveal that on the structurally flat {0 0 1} terminated MgO substrate (cubic MgO) a rough Mg layer forms due to the unique chemical interactions between the ions on the substrate and the liquid metals. The surface roughness together with the large lattice misfits with solid Mg makes both octahedral and cubic MgO substrates impotent for heterogeneous nucleation of a-Mg. The present results may shed new light on grain refinement of Mg-alloys.

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Section: B Effects Of the Substrate Surfaces On Prenucleationmentioning

confidence: 88%

Section: A Nucleation Potency Of Mgo In Liquid Mgmentioning

confidence: 99%

Section: A Nucleation Potency Of Mgo In Liquid Mgmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Prenucleation at the Interface Between MgO and Liquid Magnesium: An Ab Initio Molecular Dynamics Study

Fang

Fan

2019

Metall Mater Trans A

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Effect of TiB2 addition on microstructure and mechanical properties of a hypereutectic high chromium cast iron

2021

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The Nature of Native MgO in Mg and Its Alloys

Wang

Ramasse

et al. 2020

Metall Mater Trans A

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Native MgO particles in Mg-alloy melts have been recently exploited as potential substrates for heterogeneous nucleation during solidification, leading to significant grain refinement of various Mg-alloys. However, our current knowledge of the nature of the native MgO particles is still limited. In this work, we study both the physical and chemical nature of the native MgO in commercial purity Mg and Mg-9Al alloy by means of advanced electron microscopy. We found that as oxidation products MgO aggregates exist in the alloy melt in three different forms: dominantly young oxide film, occasionally old oxide film and ingot skin, all consisting of discrete nano-sized MgO particles. Detailed analysis shows that the native MgO particles have an octahedral or cubic morphology, a nano-scale particle size and a log-normal size distribution. The mechanisms underlying the formation of the two types of MgO were investigated, and we found that octahedral MgO is formed by oxidation of Mg melt and cubic MgO by oxidation of Mg vapor. With a large lattice misfit with a-Mg, the native MgO particles are impotent for heterogeneous nucleation, but can be made effective for grain refinement.

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Competitive Heterogeneous Nucleation Between Zr and MgO Particles in Commercial Purity Magnesium

Cited by 28 publications

References 34 publications

Prenucleation at the Interface Between MgO and Liquid Magnesium: An Ab Initio Molecular Dynamics Study

Prenucleation at the Interface Between MgO and Liquid Magnesium: An Ab Initio Molecular Dynamics Study

Effect of TiB2 addition on microstructure and mechanical properties of a hypereutectic high chromium cast iron

The Nature of Native MgO in Mg and Its Alloys

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