Observation and kinetic analysis of a metastable b.c.c. phase in rapidly solidified Ni9at.%Zr and Ni8at.%Zr1at.%X alloys

Ghosh, Gautam

doi:10.1016/0921-5093(94)90425-1

Cited by 19 publications

(10 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…15) and therefore can nucleate faster than the fcc or hcp phases even in the cases when the bcc phase is only metastable. This phenomenon was indeed observed both in experiment 1,[8][9][10]16,17 and in atomistic simulation. 2,11,[18][19][20] Therefore, both hcp and bcc phases can show up even at large supercoolings in Tb.…”

Section: Introductionsupporting

confidence: 64%

“…The nucleation and growth proceed much faster in single component systems and a phase completion was observed in single component systems where fcc is the most stable phase. 1,2,[8][9][10][11][12][13] In this case, the nucleation under a large supercooling can start from the formation of the bcc phase which usually quickly transforms into the fcc phase. As we will show below, in the case of the Tb potential developed in Ref.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Molecular dynamics simulation of phase competition in terbium

Song

Mendelev

2018

The Journal of Chemical Physics

View full text Add to dashboard Cite

The competition among multiple solid phases determines the final microstructures of a material. Such competition can originate at the very beginning of the solidification process. We report the results of molecular dynamics simulation of the phase competition between the hexagonal close-packed (hcp), facecentered cubic (fcc), and body-centered cubic (bcc) phases during the solidification of pure Tb. We found that the liquid supercooled below the hcp melting temperature has both bcc and hcp/fcc nuclei, but only the bcc nuclei grow such that the liquid always solidifies into the bcc phase, even at temperatures where the hcp phase is more stable. The hcp phase can only form in the last liquid droplet or at the bcc grain boundaries. Depending on the bcc grain orientations, the hcp phase jammed between the bcc grains either completely disappears or slowly grows via a solid-state massive transformation mechanism. Once the hcp phase becomes large enough, the stresses associated with its appearance can trigger a martensitic transformation. Yet, not the entire bcc phase is consumed by the martensitic transformation and the remaining bcc phase is transformed into the hcp phase via the solid-state massive transformation mechanism. Finally, if the supercooling is too large, the nucleation becomes almost barrier free and the liquid solidifies into a structure consisting of ultrafine hcp and bcc grains after which the bcc phase quickly disappears.

show abstract

Section: Introductionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of phase competition in terbium

Song

Mendelev

2018

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Metastable crystal phases can often influence or dominate the solidification process in deeply undercooled liquids. For example, it is well known from experimental, [1][2][3][4] computational, 5,6 and theoretical 7,8 studies that a body-centered cubic (bcc) phase can nucleate first and then transform into a pure face-centered cubic (fcc) phase in systems where the fcc phase is the most stable phase from 0 K to its melting temperature. This phenomenon can be explained by the fact that the bccliquid interface free energy is smaller than the fcc-liquid interface energy in the same system.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of the solid-liquid interface migration in terbium

Mendelev

Zhang

Song

et al. 2018

The Journal of Chemical Physics

View full text Add to dashboard Cite

We developed a Tb embedded atom method potential which properly reproduces the liquid structure obtained from the ab initio molecular dynamics simulation, the hexagonal close packed (hcp)-body-centered cubic (bcc) phase transformation, and melting temperatures. At least three crystal phases [hcp, face-centered cubic (fcc), and bcc] described by this potential can coexist with the liquid phase. Thus, the developed potential provides an excellent test bed for studies of the completive phase nucleation and growth in a single component system. The molecular dynamics simulation showed that all crystal phases can grow from the liquid phase close to their melting temperatures. However, in the cases of the hcp and fcc growth from the liquid phase at very large supercoolings, the bcc phase forms at the solid-liquid interface in the close packed orientations in spite of the fact that both hcp and fcc phases are more stable than the bcc phase at these temperatures. This bcc phase closes the hcp and fcc phase from the liquid such that the remaining liquid solidifies into the bcc phase. The initial hcp phase then slowly continues growing in expense of the bcc phase.

show abstract

“…In deeply undercooled liquids, metastable solid phases can often influence or dominate the nucleation process, to the extent that metastable phase diagrams have been proposed on the basis of experimental results [1]. The influence of metastable phases is particularly well-documented for pure face-centered cubic (fcc) metals in which the body-centered cubic (bcc) structure is metastable; several experimental [1][2][3][4], computational [5,6] and theoretical [7,8] studies have shown that the bcc phase can nucleate first and then transform into the equilibrium fcc structure. This phenomenon is in accordance with the phase-selection principle proposed by Stranski and Totomanow [9], who suggested that the phase that appears first has the lowest nucleation barrier, and is not necessarily either the thermodynamically stable phase or the most energetically favorable phase for a given undercooling.…”

Section: Introductionmentioning

confidence: 99%

“…The value obtained by averaging over all inclinations is γ 0 = 345.9 mJ m −2 for B33 and γ 0 = 133.6 mJ m −2 for B2. In (c), the nucleation barrier G * for each phase is plotted as a function of temperature using equation(2). The nucleation barrier diverges at the melting point of each phase.…”

mentioning

confidence: 99%

Appearance of metastable B2 phase during solidification of Ni₅₀Zr₅₀alloy: electrostatic levitation and molecular dynamics simulation studies

Quirinale

Rustan

Wilson

et al. 2015

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

High-energy x-ray diffraction measurements of undercooled, electrostatically levitated Ni50Zr50 liquid droplets were performed. The observed solidification pathway proceeded through the nucleation and growth of the metastable B2 phase, which persisted for several seconds before the rapid appearance of the stable B33 phase. This sequence is shown to be consistent with predictions from classical nucleation theory using data obtained from molecular dynamics (MD) simulations. A plausible mechanism for the B2-B33 transformation is proposed and investigated through further MD simulations.

show abstract

Observation and kinetic analysis of a metastable b.c.c. phase in rapidly solidified Ni9at.%Zr and Ni8at.%Zr1at.%X alloys

Cited by 19 publications

References 15 publications

Molecular dynamics simulation of phase competition in terbium

Molecular dynamics simulation of phase competition in terbium

Molecular dynamics simulation of the solid-liquid interface migration in terbium

Appearance of metastable B2 phase during solidification of Ni₅₀Zr₅₀alloy: electrostatic levitation and molecular dynamics simulation studies

Contact Info

Product

Resources

About

Observation and kinetic analysis of a metastable b.c.c. phase in rapidly solidified Ni9at.%Zr and Ni8at.%Zr1at.%X alloys

Cited by 19 publications

References 15 publications

Molecular dynamics simulation of phase competition in terbium

Molecular dynamics simulation of phase competition in terbium

Molecular dynamics simulation of the solid-liquid interface migration in terbium

Appearance of metastable B2 phase during solidification of Ni50Zr50alloy: electrostatic levitation and molecular dynamics simulation studies

Contact Info

Product

Resources

About

Appearance of metastable B2 phase during solidification of Ni₅₀Zr₅₀alloy: electrostatic levitation and molecular dynamics simulation studies