Crystal Structure Of Hexagonal Phases And Its Relation To Icosahedral Quasicrystalline Phase In Zn-Mg-RE (RE = Rare Earth) System

1998 ◽  
Vol 553 ◽  
Author(s):  
Hiroyuki Takakura ◽  
T. J. Sato ◽  
A. P. Tsai ◽  
A. Sato ◽  
A. Yamamoto
Keyword(s):  
Rare Earth ◽  
Structural Model ◽  
Lattice Parameter ◽  
Icosahedral Phase ◽  
Quasicrystalline Phase ◽  
Earth System ◽  
X Ray Diffraction ◽  
Icosahedral Quasicrystalline Phase ◽  
Two Phases ◽  
Icosahedral Quasicrystalline

AbstractA relationship between hexagonal phases in the Zn-Mg-RE (RE=rare earth) system and icosahedral quasicrystalline phase is discussed. There are three hexagonal phases in the vicinity of Zn6Mg3RE1 which are related with a lattice parameters by a ratio 3:5:7 but with approximately the same c parameters. A structural model for the phase with medium a lattice parameter is proposed based on the structures of the other two phases recently determined. We also show a preliminary result of X-ray diffraction study of the Zn-Mg-Ho icosahedral phase.

On the Mechanical Milling of the AlCuFe Icosahedral Phase with Water

2014 ◽  
Vol 793 ◽  
pp. 23-27
Author(s):  
C. Patiño-Carachure ◽  
J. Luis López-Miranda ◽  
F. de la Rosa ◽  
M. Abatal ◽  
R. Pérez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Milling Time ◽  
Induction Furnace ◽  
Icosahedral Phase ◽  
Quasicrystalline Phase ◽  
X Ray Diffraction ◽  
Cast Sample ◽  
X Ray ◽  
Transmission Electron ◽  
Icosahedral Quasicrystalline

In this investigation the Al64Cu24Fe12 alloy was melted in an induction furnace and solidified under normal casting conditions. The as-cast sample was subject to a heat treatment at 700 oC under argon atmosphere in order to obtain the icosahedral quasicrystalline phase in a monophase region. Subsequently, the icosahedral phase was milled for different times and water added conditions. The pre-alloyed and milled powders were characterized using scanning electron microscopy, X-Ray diffraction, and transmission electron microscopy. The experimental results showed that the icosahedral phase is sensitive to the reaction between water and aluminum of the quasicrystalline alloy to generate hydrogen. As the milling time and the amount of water are increased, the embrittlement reaction of the alloy is accentuated releasing more hydrogen.

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.

Quasicrystalline phase formation in Al62Cu22.5Fe12.5 and Al55Cu22.5Fe12.5Be7 alloys

2001 ◽  
Vol 16 (6) ◽  
pp. 1535-1540 ◽  
Author(s):  
S. M. Lee ◽  
B. H. Kim ◽  
D. H. Kim ◽  
W. T. Kim
Keyword(s):  
Heat Treatment ◽  
Icosahedral Phase ◽  
Partial Replacement ◽  
Quasicrystalline Phase ◽  
Icosahedral Structure ◽  
High Quality ◽  
Icosahedral Quasicrystalline Phase ◽  
Face Centered ◽  
Icosahedral Quasicrystalline ◽  
Conventionally Cast

Formation of the icosahedral quasicrystalline phase in conventionally cast Al62Cu25.5Fe12.5 and Al55Cu25.5Fe12.5Be7 alloys were investigated. The icosahedral phase (I-phase) forming ability was greatly improved by partial replacement of Al by 7 at.% Be. The as-cast Al55Cu25.5Fe12.5Be7 alloy consisted of dendritic primary I-phase and interdendritic τ-phase, whereas that of an as-cast Al62Cu25.5Fe12.5 alloy consisted of various phases such as the β-, I-, and τ-phases, together with a small amount of the λ- and η-phases. The kinetic barrier for transformation into single I-phase by heat treatment was greatly reduced in an Al55Cu25.5Fe12.5Be7 alloy. The I-phase in an Al55Cu25.5Fe12.5Be7 alloy has the same face centered icosahedral structure as that in an Al62Cu25.5Fe12.5 alloy and is of high quality without phason strain.

Preparation and Mechanical Properties of a Bulk Icosahedral Quasicrystalline Ti-Zr-Sc-Ni Alloy

2011 ◽  
Vol 415-417 ◽  
pp. 1153-1156
Author(s):  
Xin Lu Wang ◽  
Wan Qiang Liu ◽  
Shan Shan Zhang ◽  
Li Min Wang
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Icosahedral Phase ◽  
Quasicrystalline Phase ◽  
Compressive Test ◽  
Ni Alloy ◽  
Cast Alloys ◽  
Icosahedral Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline ◽  
Brittle Cleavage Fracture

The discovery of the icosahedral quasicrystalline phase (i-phase) in as-cast Ti40.83Zr40.83-xScxNi18.34(x = 0~2.0) alloys is described herein. The effect of Sc on the structure and mechanical properties of the bulk quasicrystalline alloys is investigated. The results show that the phase structure of the as-cast alloys are mainly composed of icosahedral phase accompanied by minor C14 Laves phase (L-phase), and the mechanical properties of the bulk quasicrystalline alloys have been examined at room temperature, the compressive fracture strength first increased and then decreased with increasing x from 0.4 to 2.0, and the highest strength is near 1400 MPa when x =1.2, it was 380 MPa higher than the without Sc alloy. The bulk quasicrystalline alloy exhibits the elastic deformation by the compressive test, and the fracture mode was brittle cleavage fracture.

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.

Thermodynamic and kinetic properties of an icosahedral quasicrystalline phase in the Al-Pd-Tc system

2000 ◽  
Vol 42 (12) ◽  
pp. 2177-2183 ◽  
Author(s):  
M. N. Mikheeva ◽  
G. Kh. Panova ◽  
A. A. Teplov ◽  
M. N. Khlopkin ◽  
N. A. Chernoplekov ◽  
...  
Keyword(s):  
Quasicrystalline Phase ◽  
Kinetic Properties ◽  
Icosahedral Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline
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