Undercooling and solidification behaviour of melts of the quasicrystal-forming alloysAl–Cu–Fe and Al–Cu–Co

Holland‐Moritz, D.; Schroers, Jan; Herlach, D.M.; Grushko, B.; Urban, K.

doi:10.1016/s1359-6454(97)00341-8

Cited by 84 publications

(45 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is the first direct evidence that verifies Frank's hypothesis [68]. It was also reported that the activation energy for nucleation is lower for an icosahedral cluster than for cubic base clusters in a number of Al alloys [56]. For the same reason, we can expect to observe the icosahedral order in undercooled liquids of the Al-Pd-Cr alloys.…”

Section: Discussionsupporting

confidence: 80%

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy^∗

Tsai

2008

Science and Technology of Advanced Materials

121

View full text Add to dashboard Cite

We review the stability of various icosahedral quasicrystals (iQc) from a metallurgical viewpoint. The stability of stable iQcs is well interpreted in terms of Hume-Rothery rules, i.e. atomic size factor and valence electron concentration, e/a. For metastable iQcs, we discuss the role of phason disorder introduced by rapid solidification, in structural stability and its interplay with chemical order and composition.

show abstract

Section: Discussionsupporting

confidence: 80%

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy^∗

Tsai

2008

Science and Technology of Advanced Materials

121

View full text Add to dashboard Cite

show abstract

“…In earlier studies was calculated to be 0.86 for face centered cubic and hexagonal close-packed structures, and 0.71 for a body centered cubic structure [18]. However, is much smaller ( 0:3) for icosahedral quasicrystals [19,20] and increases from 0.3 to 0.7 for phases with decreasing polytetrahedral order. The entropy difference between the liquid and the crystal decreases with deeper undercooling until it vanishes at the Kauzmann temperature [21].…”

Section: Prl 94 245501 (2005) P H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 90%

Influence of Kinetic and Thermodynamic Factors on the Glass-Forming Ability of Zirconium-Based Bulk Amorphous Alloys

et al. 2005

Self Cite

View full text Add to dashboard Cite

The time-temperature-transformation curves for three zirconium-based bulk amorphous alloys are measured to identify the primary factors influencing their glass-forming ability. The melt viscosity is found to have the most pronounced influence on the glass-forming ability compared to other thermodynamic factors. Surprisingly, it is found that the better glass former has a lower crystal-melt interfacial tension. This contradictory finding is explained by the icosahedral short-range order of the undercooled liquid, which on one hand reduces the interfacial tension, while on the other hand increases its viscosity. DOI: 10.1103/PhysRevLett.94.245501 PACS numbers: 61.43.Fs, 66.20.+d, 81.05.Kf, 81.10.Aj In recent years, several multicomponent alloys have been developed that can be cast in bulk amorphous form with cooling rates as low as 1 K=s [1][2][3]. Attempts have been made to explain the exceptional stability against crystallization in these systems by both kinetic and thermodynamic principles [4 -6]. From a kinetic point of view, the dynamic viscosity is an important parameter to describe the time scale for structural rearrangement of the undercooled liquid atoms for the growth of a crystal nucleus. From a thermodynamic point of view, the better glass former is expected to have a lower thermodynamic driving force for crystallization, which is given by the Gibbs free energy difference between the liquid and crystal, G. Particularly, in classical nucleation theory [7,8], the activation barrier for nucleation, G is expressed aswhere is the crystal-melt interfacial tension. It is clear from Eq. (1) that lower thermodynamic driving force and higher interfacial tension will lead to greater stability of the undercooled melt against crystallization. While a number of studies address the influence of thermodynamic and kinetic factors on the stability of undercooled liquids, no studies on their relative importance have been carried out to date. Also, there are no investigations dealing with correlations between the kinetic and thermodynamic factors to determine whether they stem from the same underlying property of the undercooled liquid. In this study, we investigate the influence of G, melt viscosity, and crystal-melt interfacial tension on the glass-forming ability of three zirconium-based bulk amorphous alloys: Zr 41:2 Ti 13:8 Cu 12:5 Ni 10 Be 22:5 (Vit1), Zr 57 Cu 15:4 Ni 12:6 Al 10 Nb 5 (Vit106), and Zr 55 Al 22:5 Co 22:5 (ZAC). These three alloys were chosen because of their widely different glass-forming abilities, but otherwise similar properties. The time-temperature-transformation (TTT) diagrams of these alloys, which give a quantitative measure of their glass-forming ability, were measured using the high-vacuum electrostatic levitation (HVESL) technique to eliminate any heterogeneous nucleation effects. A detailed description of the ESL facility is given elsewhere [9].The alloys were prepared from high purity starting materials in an arc melter. The glass-transition temperatures, T g , and the liquidus tempe...

show abstract

“…[33] Later on, Spaepen developed an extended model for the interfacial energy that does take into account also the enthalpic term besides the entropic contribution. [39] Investigations of bcc vs fcc nucleation in Fe-Ni alloys [40] and Fe-Ni-Cr steel alloys [41] and in particular undercooling nucleation investigations on stable and metastable quasicrystalline phases [42] leads to the conclusion that the enthalpic contribution to the interfacial energy is small compared to the entropic term. Similar investigations of nucleation undercooling were performed for Co-Pd alloys.…”

Section: A Structural Short-range Ordermentioning

confidence: 99%

Containerless Undercooled Melts: Ordering, Nucleation, and Dendrite Growth

Herlach

Binder

Galenko

et al. 2015

Metall Mater Trans A

View full text Add to dashboard Cite

Electromagnetic and electrostatic levitation are applied to containerless undercool and solidify metallic melts. A large undercooling range becomes accessible with the extra benefit that the freely suspended drop is accessible directly for in situ observation. The short-range order in undercooled melts is investigated by combining levitation with elastic neutron scattering and X-ray scattering using synchrotron radiation. Muon Spin Rotation (lSR) experiments show magnetic ordering in deeply undercooled Co 80 Pd 20 alloys. The onset of magnetic ordering stimulates nucleation. Results on nucleation undercooling of zirconium are presented showing the limit of maximum undercoolability set by the onset of homogeneous nucleation. Metastable phase diagrams are determined by applying energy-dispersive X-ray diffraction of Ni-V alloys with varying concentration. Nucleation is followed by crystal growth. Rapid dendrite growth velocity is measured on levitation-processed samples as a function of undercooling DT by using high-speed video camera technique. Solute trapping in dilute solid solutions and disorder trapping in intermetallic compounds are experimentally verified. Measurements of glass-forming Cu-Zr alloy show a maximum in the V(DT) relation that is indicative for diffusion-controlled growth. The influence of convection on dendrite growth of Al 50 Ni 50 is shown by comparative measurements of dendrite growth velocity on Earth and in reduced gravity. Eventually, faceting of a rough interface by convection is presented as observed on Ni 2 B alloys.

show abstract

Undercooling and solidification behaviour of melts of the quasicrystal-forming alloysAl–Cu–Fe and Al–Cu–Co

Cited by 84 publications

References 40 publications

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy^∗

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy^∗

Influence of Kinetic and Thermodynamic Factors on the Glass-Forming Ability of Zirconium-Based Bulk Amorphous Alloys

Containerless Undercooled Melts: Ordering, Nucleation, and Dendrite Growth

Contact Info

Product

Resources

About

Undercooling and solidification behaviour of melts of the quasicrystal-forming alloysAl–Cu–Fe and Al–Cu–Co

Cited by 84 publications

References 40 publications

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy∗

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy∗

Influence of Kinetic and Thermodynamic Factors on the Glass-Forming Ability of Zirconium-Based Bulk Amorphous Alloys

Containerless Undercooled Melts: Ordering, Nucleation, and Dendrite Growth

Contact Info

Product

Resources

About

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy^∗

Icosahedral clusters, icosaheral order and stability of quasicrystals—a view of metallurgy^∗