Exelfs As A Tool For Investigating The Local Structure Of Bulk Glass-Forming Metal Alloys

1999 ◽  
Vol 5 (S2) ◽  
pp. 138-139
Author(s):  
F, M. Alamgir ◽  
Y. Ito ◽  
D. B. Williams ◽  
H. Jain
Keyword(s):  
Metallic Glasses ◽  
Local Structure ◽  
Chemical Interaction ◽  
Random Packing ◽  
Metallic Alloys ◽  
Metal Alloys ◽  
Bulk Glass ◽  
Glass Forming ◽  
Structure Of Glasses ◽  
Intellectual Challenge

The discovery of amorphous, or glassy, metallic alloys in 1959 posed an intellectual challenge. How can one describe the structure of glasses when there is no long-range periodicity? What can the structure tell us about why certain metal alloys form glasses more easily than others? First, some universal characteristics, if any exist, of the structure metallic glasses needed to be found. A convincing model was proposed for the structure of metallic glasses based on Bernal’s dense random packing (DRP) structure. Central to this proposal is the idea that the structure of metallic glasses is that of the random filling of space by non-interacting identical spheres. In this model, strongly directional interatomic bonds do not play an important role in determining the structure of metallic glasses. This model is hpwever in conflict with one proposed by Chen, which correlates increased glass formability with increased chemical interaction between dissimilar atoms.

Bulk Glass-Forming Metallic Alloys: Science and Technology

MRS Bulletin ◽  
1999 ◽  
Vol 24 (10) ◽  
pp. 42-56 ◽  
Author(s):  
William L. Johnson
Keyword(s):  
Metallic Glasses ◽  
Liquid Metals ◽  
Rapid Quenching ◽  
Metallic Alloys ◽  
Bulk Glass ◽  
Related Field ◽  
Glass Forming ◽  
Metallic Liquids ◽  
Potential Applications ◽  
Liquid Metal Alloy

The following article is based on the MRS Medal talk presented by William L. Johnson at the 1998 MRS Fall Meeting on December 2, 1998. The MRS Medal is awarded for a specific outstanding recent discovery or advancement that has a major impact on the progress of a materials-related field. Johnson received the honor for his development of bulk metallic glass-forming alloys, the fundamental understanding of the thermodynamics and kinetics that control glass formation and crystallization of glass-forming liquids, and the application of these materials in engineering.The development of bulk glass-forming metallic alloys has led to interesting advances in the science of liquid metals. This article begins with brief remarks about the history and background of the field, then follows with a discussion of multicomponent glass-forming alloys and deep eutectics, the chemical constitution of these new alloys, and how they differ from metallic glasses of a decade ago or earlier. Recent studies of deeply undercooled liquid alloys and the insights made possible by their exceptional stability with respect to crystallization will then be discussed. Advances in this area will be illustrated by several examples. The article then describes some of the physical and specific mechanical properties of bulk metallic glasses (BMGs), and concludes with some interesting potential applications.The first liquid-metal alloy vitrified by cooling from the molten state to the glass transition was Au-Si, as reported by Duwez at Caltech in 1960. Duwez made this discovery as a result of developing rapid quenching techniques for chilling metallic liquids at very high rates of 105–106 K/s.

Bulk Glass-Forming Metallic Alloys: Science and Technology [1998 Mrs Medal Award Lecture, Presented at Symposium Mm]

1998 ◽  
Vol 554 ◽  
Author(s):  
William L. Johnson
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Metallic Alloys ◽  
Bulk Glass ◽  
Glass Forming ◽  
Chemical Constitution ◽  
Potential Applications ◽  
Multicomponent Glass ◽  
Exceptional Stability ◽  
Made In

AbstractThe paper begins with some brief remarks about the history and background of the field of bulk glass-forming metallic alloys. This is followed by a discussion of multicomponent glass-forming alloys and deep eutectics, the chemical constitution of these new alloys, and how they differ from metallic glasses of a decade ago or earlier. The development of bulk glass forming alloys has led to interesting studies of the deeply undercooled liquid alloys, which are made possible by the exceptional stability with respect to crystallization. Recent advances made in this area will be illustrated by several examples. The paper continues with a discussion of some of the physical properties of bulk metallic glasses. Mechanical properties are specifically discussed. Some interesting potential applications of bulk metallic glasses will be mentioned.

Mg–Ca–Zn Bulk Metallic Glasses with High Strength and Significant Ductility

2005 ◽  
Vol 20 (8) ◽  
pp. 1935-1938 ◽  
Author(s):  
X. Gu ◽  
G.J. Shiflet ◽  
F.Q. Guo ◽  
S.J. Poon
Keyword(s):  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Mass Density ◽  
High Strength ◽  
Light Metal ◽  
Glass Forming Ability ◽  
Bulk Glass ◽  
Bulk Amorphous Alloys ◽  
Specific Strength ◽  
Glass Forming

The development of Mg–Ca–Zn metallic glasses with improved bulk glass forming ability, high strength, and significant ductility is reported. A typical size of at least 3–4 mm amorphous samples can be prepared using conventional casting techniques. By varying the composition, the mass density of these light metal based bulk amorphous alloys ranges from 2.0 to 3.0 g/cm3. The typical measured microhardness is 2.16 GPa, corresponding to a fracture strength of about 700 MPa and specific strength of around 250–300 MPa cm3/g. Unlike other Mg- or Ca-based metallic glasses, the present Mg–Ca–Zn amorphous alloys show significant ductility.

Bulk Glass Formation in an Fe-Based Fe–Y–Zr–M (M = Cr, Co, Al)–Mo–B System

2004 ◽  
Vol 19 (3) ◽  
pp. 921-929 ◽  
Author(s):  
Z.P. Lu ◽  
C.T. Liu ◽  
C.A. Carmichael ◽  
W.D. Porter ◽  
S.C. Deevi
Keyword(s):  
Metallic Glasses ◽  
Glass Formation ◽  
Amorphous Alloys ◽  
High Strength ◽  
Supercooled Liquid ◽  
Glass Forming Ability ◽  
Bulk Glass ◽  
Bulk Amorphous Alloys ◽  
Glass Forming ◽  
Hardness Values

Several new bulk metallic glasses based on Fe–Y–Zr–(Co, Cr, Al)–Mo–B, which have a glass-forming ability superior to the best composition Fe61Zr10Co7Mo5W2B15 reported recently, have been successfully developed. The as-cast bulk amorphous alloys showed a distinctly high thermal stability with glass-transition temperatures above 900 K, supercooled liquid regions above 60 K, and high strength with Vickers hardness values larger than HV 1200. The suppression of the growth of primary phases in the molten liquids and the resultant low liquidus temperatures were found to be responsible for the superior glass-forming ability in these new alloys. It was found that the addition of 2% Y not only facilitated bulk glass formation, but the neutralizing effect of Y with oxygen in the molten liquids also improved the manufacturability of these amorphous alloys.

Retracted Article: Atomic-scale simulation to study the dynamical properties and local structure of Cu–Zr and Ni–Zr metallic glass-forming alloys

2016 ◽  
Vol 18 (10) ◽  
pp. 7169-7183 ◽  
Author(s):  
M. H. Yang ◽  
Y. Li ◽  
J. H. Li ◽  
B. X. Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Metallic Glasses ◽  
Local Structure ◽  
Supercooled Liquids ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Glass Forming ◽  
Retracted Article ◽  
Dynamical Properties

Molecular dynamics simulation with well-developed EAM potentials was carried out to investigate the transport properties and local atomic structure of Cu–Zr and Ni–Zr metallic glasses and supercooled liquids.

Roles of alloying additions on local structure and glass-forming ability of Cu–Zr metallic glasses

2013 ◽  
Vol 49 (2) ◽  
pp. 496-503 ◽  
Author(s):  
B. F. Lu ◽  
L. T. Kong ◽  
Z. Jiang ◽  
Y. Y. Huang ◽  
J. F. Li ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Local Structure ◽  
Glass Forming Ability ◽  
Alloying Additions ◽  
Glass Forming
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