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.

Formation of nano icosahedral quasicrystalline phase in Zr-Ni-M (M=Pd, Au, Pt) ternary glassy alloys

2001 ◽  
Vol 250 (1) ◽  
pp. 285-288
Author(s):  
Junji Saida ◽  
Mitsuhide Matsushita ◽  
Chunfei Li ◽  
Akihisa Inoue
Keyword(s):  
Quasicrystalline Phase ◽  
Glassy Alloys ◽  
Icosahedral Quasicrystalline Phase ◽  
Icosahedral Quasicrystalline

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.

Formation of Nano Icosahedral Quasicrystalline Phase in Zr-based Binary and Ternary Glassy Alloys

2000 ◽  
Vol 644 ◽  
Author(s):  
Junji Saida ◽  
Mitsuhide Matsushita ◽  
Akihisa Inoue
Keyword(s):  
Binary Alloy ◽  
Short Range ◽  
Short Range Order ◽  
Glassy Alloy ◽  
Icosahedral Phase ◽  
Range Order ◽  
Ternary Alloys ◽  
Quasicrystalline Phase ◽  
Glassy Alloys ◽  
The Difference

AbstractIt is found that a nano icosahedral phase with diameters below 50 nm is formed as a primary phase in the Zr70Ni10M20, Zr70TM10Pd20, Zr70Au10Pd20 and Zr75Pt10Pd15 ternary and Zr70Pd30 binary glassy alloys. The nanoscale icosahedral phase in the diameter range below 10 nm was also found to be formed directly in the melt-spun Zr80Pt20 binary alloy. These icosahedral phases transform to the crystalline phase(s) at the higher annealing temperature. The nucleation kinetics for the precipitation of the icosahedral phase from supercooled liquid were examined in the Zr70Pd30 and Zr70Ni10Pd20 glassy alloys. It was clarified that the transformation of both alloys proceeds in the diffusion-controlled growth mode with increasing nucleation rate. The formation of the nanometer-scale icosahedral phase is due to the transformation mode. The activation energy of nucleation is evaluated to be 267 kJmol−1 for the binary alloy and 311 kJmol−1 for the ternary alloy. The difference between the two alloy systems seems to originate from the difference in the number of atoms for rearrgements in the nucleation mode. The short-range ordering is observed in the as-quenched Zr70Pd30 glassy alloy, which is indicative of the icosahedral structure. The formation of the nano-scale icosahedral phase in the Zr-based binary and ternary alloys is due to the existence of an icosahedral short-range order in the glassy or liquid state. It is suggested that the icosahedral short-range order is stabilized by the restraint of the long-range atomic rearrangements that lead to the transition to a periodic structure by the strong chemical affinities of Pd or Pt with Zr.

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.

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.

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