Precipitation of icosahedral quasicrystalline phase in Hf69.5Al7.5Ni11Cu12 metallic glass

2001 ◽  
Vol 16 (4) ◽  
pp. 1190-1194 ◽  
Author(s):  
Chunfei Li ◽  
Akihisa Inoue
Keyword(s):  
Metallic Glass ◽  
Melt Spinning ◽  
Crystallization Process ◽  
Exothermic Reaction ◽  
Quasicrystalline Phase ◽  
Scanning Calorimetry ◽  
Exothermic Reactions ◽  
Transmission Electron ◽  
Icosahedral Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline

A Hf69.5Al7.5Ni11Cu12 metallic glass was prepared by a single roller melt-spinning method, and the crystallization process was studied by x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The metallic glass crystallizes through three exothermic reactions. The low-temperature exothermic reaction corresponded to the precipitation of an icosahedral quasicrystalline phase. Further annealing at higher temperature led to the decomposition of the icosahedral quasicrystalline phase to other stable crystalline phases, indicating that the precipitated icosahedral quasicrystalline phase was in a metastable state. The crystallization process of the present alloy was compared with that of other Hf–Al–Ni–Cu alloys, and the reason for the precipitation of the icosahedral quasicrystalline phase was discussed.

scholarly journals Structural Characterization of Al65Cu20Fe15 Melt-Spun Alloy by X-ray, Neutron Diffraction, High-Resolution Electron Microscopy and Mössbauer Spectroscopy

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 54
Author(s):  
Rafał Babilas ◽  
Katarzyna Młynarek ◽  
Wojciech Łoński ◽  
Dariusz Łukowiec ◽  
Mariola Kądziołka-Gaweł ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Neutron Diffraction ◽  
Quasicrystalline Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Icosahedral Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline

The aim of the work was to characterize the structure of Al65Cu20Fe15 alloy obtained with the use of conventional casting and rapid solidification-melt-spinning technology. Based on the literature data, the possibility of an icosahedral quasicrystalline phase forming in the Al-Cu-Fe was verified. Structure analysis was performed based on the results of X-ray diffraction, neutron diffraction, 57Fe Mössbauer and transmission electron microscopy. Studies using differential scanning calorimetry were carried out to describe the crystallization mechanism. Additionally, electrochemical tests were performed in order to characterize the influence of the structure and cooling rate on the corrosion resistance. On the basis of the structural studies, the formation of a metastable icosahedral phase and partial amorphous state of ribbon structure were demonstrated. The possibility of the formation of icosahedral quasicrystalline phase I-AlCuFe together with the crystalline phases was indicated by X-ray diffraction (XRD), neutron diffraction (ND) patterns, Mössbauer spectroscopy, high-resolution transmission electron microscopy (HRTEM) observations and differential scanning calorimetry (DSC) curves. The beneficial effect of the application of rapid solidification on the corrosive properties was also confirmed.

Formation of Icosahedral Quasicrystalline Phase in Zr70TM10Pd20 (TM = Fe, Co, or Cu) Ternary Glassy Alloys

2000 ◽  
Vol 15 (6) ◽  
pp. 1280-1283 ◽  
Author(s):  
M. Matsushita ◽  
J. Saida ◽  
C. Li ◽  
A. Inoue
Keyword(s):  
Glassy Alloy ◽  
Exothermic Reaction ◽  
Icosahedral Phase ◽  
Exothermic Peak ◽  
Quasicrystalline Phase ◽  
Glassy Alloys ◽  
Stage Crystallization ◽  
Icosahedral Quasicrystalline Phase ◽  
Primary Precipitation ◽  
Icosahedral Quasicrystalline

A nanoscale icosahedral quasicrystalline phase was confirmed as a primary precipitation phase in the melt-spun Zr70TM10Pd20 (TM = Fe, Co, or Cu) ternary glassy alloys with a two-stage crystallization process. The onset temperature of the transformation from amorphous to icosahedral phase is 713 K for Fe-, 696 K for Co-, and 680 K for Cu-containing alloys at the heating rate of 0.67 Ks−1. The size of the icosahedral particles is in the range of 20 to 50 nm for the Zr70Cu10Pd20 glassy alloy annealed for 120 s at 720 K. The icosahedral phase has a very fine particle size in a diameter range below 10 nm for the Zr70Fe10Pd20 and Zr70Co10Pd20 alloys. The crystallization reaction after the first exothermic peak results in the transition from the icosahedral to crystalline phases through a sharp exothermic reaction. Thus, the formation of the nanoscale icosahedral phase indicates the possibility that an icosahedral short-range order exists in the present glassy alloys.

TEM study of the early stages of the precipitation process in strip-cast Al3003 alloys

1992 ◽  
Vol 7 (12) ◽  
pp. 3235-3241 ◽  
Author(s):  
Y.F. Cheng ◽  
V. Hansen ◽  
J. Gj⊘nnes ◽  
L. Reine Wallenberg
Keyword(s):  
Quasicrystalline Phase ◽  
Precipitation Process ◽  
Precipitation Behavior ◽  
Secondary Particles ◽  
Transmission Electron ◽  
Cast Alloys ◽  
Strip Cast ◽  
Icosahedral Quasicrystalline Phase ◽  
Si Content ◽  
Icosahedral Quasicrystalline

The precipitation behavior, especially the early nucleation stages, of the industrial strip-cast Al3003 alloys was investigated by using transmission electron microscopy (TEM). An icosahedral quasicrystalline phase was found as secondary particles in these strip-cast alloys after heat treatment for a few seconds. Three different nucleation paths are proposed based on the TEM observations. They have the same origin, viz. (Mn, Fe)-containing Mackay icosahedra, and are governed by the composition of alloys, especially the Mn and Si content.

Precipitation of icosahedral quasicrystalline phase in Hf65Al7.5Ni10Cu12.5Pd5 metallic glass

2000 ◽  
Vol 77 (4) ◽  
pp. 528-530 ◽  
Author(s):  
Chunfei Li ◽  
Junji Saida ◽  
Mitsuhide Matsushita ◽  
Akihisa Inoue
Keyword(s):  
Metallic Glass ◽  
Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline

Precipitation of icosahedral phase from amorphous Zr65Cu17.5−xAl7.5Ni10Agx (x = 0, 5) alloys

2001 ◽  
Vol 16 (5) ◽  
pp. 1311-1317 ◽  
Author(s):  
J. K. Lee ◽  
G. Choi ◽  
W. T. Kim ◽  
D. H. Kim
Keyword(s):  
Melt Spinning ◽  
Crystallization Behavior ◽  
Isothermal Transformation ◽  
Icosahedral Phase ◽  
Partial Replacement ◽  
Quasicrystalline Phase ◽  
Scanning Calorimetry ◽  
Crystallization Sequence ◽  
Transmission Electron ◽  
Injection Casting

Crystallization behavior of amorphous Zr65Cu17.5−xAl7.5Ni10Agx (x = 0, 5) alloys prepared by melt spinning and injection casting techniques has been studied using differential scanning calorimetry, x-ray diffractometry, and transmission electron microscopy. Ag addition changes crystallization sequence of the amorphous phase. The amorphous Zr65Cu17.5Al7.5Ni10 alloy crystallizes via simultaneous precipitation of icosahedral phase and NiZr2 phase in the first crystallization step whereas that in Zr65Cu12.5Al7.5Ni10Ag5 alloy crystallizes via precipitation of only icosahedral the phase. Partial replacement of Cu by Ag in Zr65Cu17.5Al7.5Ni10 alloy stabilized the icosahedral phase relative to competing intermetallic phases resulting in suppression of the precipitation of the NiZr2 phase, enhancement of the precipitation of icosahedral phase, and reduction of undercooled liquid range. Crystallization behavior of the amorphous Zr65Cu12.5Al7.5Ni10Ag5 alloy is not affected by cooling rate during solidification. Johnson–Mehl–Avrami analysis of isothermal transformation data suggests that the formation of the quasicrystalline phase is not entirely polymorphic in nature and may involve partitioning of the solute at later state.

Glass and Quasicrystal Formation in a Zr-based Multicomponent Alloy

2000 ◽  
Vol 644 ◽  
Author(s):  
U. Kühn ◽  
J. Eckert ◽  
N. Mattern ◽  
L. Schultz
Keyword(s):  
Amorphous Phase ◽  
Melt Spinning ◽  
Rapid Quenching ◽  
Quasicrystalline Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Copper Mold Casting ◽  
Transmission Electron ◽  
Mold Casting ◽  
Melt Spinning Technique

AbstractThe phase formation of a Zr57Ti8Nb2.5Cu13.9Ni11.1Al7.5alloy has been investigated upon cooling from the melt at different quenching rates as well as upon annealing of as-cast specimens. The different samples are characterized by x-ray diffraction, transmission electron microscopy and differential scanning calorimetry. Rapid quenching using the melt spinning technique results in amorphization. Slower cooling as realized upon copper mold casting leads to an icosaheadral quasicrystalline phase coexisting with a small amount of amorphous phase. The primarily formed quasicrystals have a grain size of about 1 νm. Upon annealing, the amorphous phase formed upon melt spinning precipitates quasicrystals in the first step of a series of transformations to the crystalline equilibrium compounds. The quasicrystals formed by annealing do not exceed a size of 5 to 10 nm.

scholarly journals Analysis of the Crystallization Kinetics and Thermal Stability of the Amorphous Mg72Zn24Ca4 Alloy

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3583
Author(s):  
Bartosz Opitek ◽  
Janusz Lelito ◽  
Michał Szucki ◽  
Grzegorz Piwowarski ◽  
Łukasz Gondek ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Amorphous Structure ◽  
Avrami Equation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Human Body Temperature ◽  
End Times

The aim of this study was to analyze the crystallization of the Mg72Zn24Ca4 metallic glass alloy. The crystallization process of metallic glass Mg72Zn24Ca4 was investigated by means of the differential scanning calorimetry. The glass-forming ability and crystallization are both strongly dependent on the heating rate. The crystallization kinetics, during the isothermal annealing, were modelled by the Johnson–Mehl–Avrami equation. Avrami exponents were from 2.7 to 3.51, which indicates diffusion-controlled grain growth. Local exponents of the Johnson–Mehl–Avrami equation were also calculated. In addition, the Mg phase—being the isothermal crystallization product—was found, and the diagram of the time–temperature phase transformation was developed. This diagram enables the reading of the start and end times of the crystallization process, occurring in amorphous ribbons of the Mg72Zn24Ca4 alloy on the isothermal annealing temperature. The research showed high stability of the amorphous structure of Mg72Zn24Ca4 alloy at human body temperature.

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