Glass formation, thermal properties, and elastic constants of La–Al–Co alloys

2010 ◽  
Vol 25 (7) ◽  
pp. 1398-1404 ◽  
Author(s):  
Ran Li ◽  
Mihai Stoica ◽  
Gang Wang ◽  
Jin Man Park ◽  
Yan Li ◽  
...  
Keyword(s):  
Elastic Constants ◽  
Metallic Glasses ◽  
Glass Formation ◽  
Elastic Moduli ◽  
Bulk Glass ◽  
Compositional Dependence ◽  
Glass Forming ◽  
Characteristic Temperatures ◽  
The Relationship ◽  
Co Alloys

The compositional dependence of glass formation and thermal and elastic properties was clarified for the ternary La–Al–Co bulk glass-forming system. The existing linear correlation between La concentration and characteristic temperatures, i.e., the glass transition temperature Tg and the onset temperature of crystallization Tx, as well as the elastic moduli in this system can give a useful guideline for the chemical design of desirable bulk metallic glasses (BMGs) with tunable physical properties in advance. The relationship between Tg and elastic constants for the La–Al–Co BMGs can be quantitatively described using a microscopic model proposed by T. Egami.

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.

scholarly journals A Local Probe into the Atomic Structure of Metallic Glasses Using EELS

1998 ◽  
Vol 554 ◽  
Author(s):  
F. M. Alamgir ◽  
Y. Ito ◽  
H. Jain ◽  
D. B. Williams ◽  
R. B. Schwarz
Keyword(s):  
Energy Loss ◽  
Metallic Glasses ◽  
Atomic Structure ◽  
Electron Energy Loss Spectroscopy ◽  
Glass Formation ◽  
Slight Modification ◽  
Bulk Glass ◽  
Glass Forming ◽  
Electron Energy Loss ◽  
Extract Information

AbstractElectron energy loss spectroscopy (EELS) is used to extract information on the topological arrangement of atoms around Pd in the bulk-glass-forming Pd60Ni20P20. It is found that the environment around Pd in the glass is only a slight modification of the Pd crystalline structure. However, the modification is enough to allow this alloy to form a glass in bulk. In examining the differences between the structure of crystalline Pd and glassy Pd60Ni20P20 it is concluded that incorporation of Ni and P into the structure frustrates the structure enough that glass formation becomes easy.

Glass Formation and Glass Forming Ability of Alloys Near Eutectic Composition

2000 ◽  
Vol 644 ◽  
Author(s):  
Y. Li
Keyword(s):  
Glass Transition ◽  
Glass Formation ◽  
Eutectic Composition ◽  
Glass Forming Ability ◽  
Critical Section ◽  
Bulk Glass ◽  
Melting Behaviour ◽  
Eutectic Alloys ◽  
Section Thickness ◽  
Glass Forming

AbstractOnset temperature, Tm and offset temperature (liquidus) Tl of melting of a series of bulk glass forming alloys based on La, Mg, and Pd have been measured by studying systematically the melting behaviour of these alloys using DTA or DSC. Bulk metallic glass formation has been found to be most effective at or near their eutectic points and less effective for off-eutectic alloys. Reduced glass transition temperature Trg given by Tg/Tl is found to show a stronger correlation with critical cooling rate or critical section thickness for glass formation than Trg given by Tg/Tm.

Investigation on Correlation between the Modified Criterion and the Glass-Forming Ability for Metallic Glasses

2010 ◽  
Vol 97-101 ◽  
pp. 591-596
Author(s):  
Wen Bin Sheng ◽  
Chun Ming Zhang ◽  
Wan Li Gu
Keyword(s):  
Aqueous Solutions ◽  
Cooling Rate ◽  
Metallic Glasses ◽  
Statistical Correlation ◽  
Glass Forming Ability ◽  
Correlation Parameter ◽  
Glass Forming ◽  
A Value ◽  
The Relationship ◽  
Modified Equation

A modified criterion γ’ (=Tx/(1.5Tg+Tl) of glass-forming ability (GFA) for metallic glasses is suggested on the basis of present criterion γ (=Tx/(Tg+Tl) that correlates well with some systems including metallic glasses, some glassy oxides and some cryo-protective aqueous solutions. Results show that the modified criterion γ’ shows stronger correlation with the critical cooling rate Rc for metallic glasses than the criterion γ, which is demonstrated by a value increase in the statistical correlation parameter R2 from 0.9022 to 0.9037. Furthermore, a modified equation is given to reflect the relationship between γ’ and Rc.

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.

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 the Ni–Zr–Ti–Nb–Si–Sn alloy system

2004 ◽  
Vol 19 (8) ◽  
pp. 2221-2225 ◽  
Author(s):  
J.Y. Lee ◽  
D.H. Bae ◽  
J.K. Lee ◽  
D.H. Kim
Keyword(s):  
Glass Formation ◽  
Liquidus Temperature ◽  
Eutectic Composition ◽  
Composition Range ◽  
Alloy System ◽  
Glass Forming Ability ◽  
Maximum Diameter ◽  
Bulk Glass ◽  
Glass Forming ◽  
Crystallization Onset

In this study, the effect of addition of Nb on glass formation in Ni–Ti–Zr–Si–Sn alloys has been studied. The composition range for bulk glass formation with Dmax > 2 mm (Dmax, maximum diameter for glass formation by injection cast method) becomes wider when compared with the non-Nb–containing alloy. The ΔTx (= Tx – Tg; Tx, crystallization onset temperature; Tg, glass transition temperature), Trg (= Tg/Tl; Tl, liquidus temperature) and γ [= Tx/(Tl + Tg)] values for the alloys Dmax > 2 mm are in the range of 40–59, 0.638–0.651, and 0.410–0.419, respectively. The compositions of the alloys (Dmax > 2 mm) are closer to pseudo-eutectic composition than that of the alloy without Nb, showing an improved glass forming ability. The critical cooling rate for glass formation (Dmax = 5 mm) is estimated to be order of approximately 40 K/s.

Cluster-Based Bulk Metallic Glass Formation in Co (-Fe)-Si-B-Nb Alloy Systems

2007 ◽  
Vol 561-565 ◽  
pp. 1275-1278 ◽  
Author(s):  
Qing Wang ◽  
Chun Lei Zhu ◽  
Yan Hui Li ◽  
Jiang Wu ◽  
Chuang Dong ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Metallic Glasses ◽  
Glass Formation ◽  
Bulk Metallic Glasses ◽  
Ternary Alloys ◽  
Glass Forming ◽  
Binary Clusters ◽  
Composition Formula ◽  
Alloy Systems

The present paper investigates the bulk metallic glass formation in Co-based alloy systems with the guidance of the cluster line and minor-alloying principles. The selected basic ternary Co-B-Si alloy compositions are intersecting points of cluster lines, defined by linking special binary clusters to the third element. Then these basic ternary alloys are further minor-alloyed with Nb and quaternary bulk metallic glasses are obtained only by 4-5 at. % Nb minor-alloying of the basic composition Co68.6B25.7Si5.7 that is developed from dense-packed cluster Co8B3. The bulk metallic glasses are expressed approximately with a unified simple composition formula: (Co8B3)1(Si,Nb)1. In addition, a quantity of Fe substitution for Co further improves the glass-forming abilities.

The Importance of Transient Nucleation and Non-Equilibrium Viscosity for Glass Formation

1985 ◽  
Vol 57 ◽  
Author(s):  
Kenneth F. Kelton
Keyword(s):  
Steady State ◽  
Metallic Glasses ◽  
Glass Formation ◽  
Volume Fraction ◽  
Molecular Cluster ◽  
Transient Effects ◽  
Glass Forming ◽  
Model Glass ◽  
Transient Nucleation ◽  
Non Equilibrium

AbstractThe process of nucleation and growth in glasses and undercooled liquids is modeled by directly simulating the evolution of the molecular cluster distribution under both isothermal and non-isothermal conditions. Results of that simulation for the nucleation rate during the quench, and for the number of nuclei produced and the volume fraction transformed at the end of the quench are presented. The following three points are discussed: (1) The importance of transient, or non-steady state, nucleation rates on glass formation is assessed by considering three model glass forming systems: lithium disilicate, a relatively good glass former, and two metallic glasses, (Au85Cu15)77Si9Gd14 and Au81Si19. (2) Using experimentally determined values for the steady state nucleation rates and growth velocities for Pd40Ni40P20, it is demonstrated that, in agreement with recent experimental results, this alloy may be cycled at rates on the order of 1 K/sec between the melting and glass transition temperatures without crystallization. Transient effects are shown to be unimportant under these conditions in this system. (3) The effect on glass formation of a non-equilibrium viscosity during the quench due to configurational freezing is evaluated by assuming a phenomenological model for the changing viscosity.

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