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Title: Recent progress in quantifying glass-forming ability of bulk metallic glasses

Abstract

The {gamma} parameter proposed by the authors has prompted a lot of new interests in quantifying glass-forming ability (GFA) of bulk metallic glasses (BMGs). As a result, many different GFA indicators/criteria have been suggested lately. Recent development in this area is summarized herein; it was found that all newly developed parameters can be grouped into three basic categories according to their definitions. Our statistical analysis, particularly the direct comparison with the {sigma} parameter developed by Park et al., shows that the universal GFA indicator ? is still the best in terms of reliability and applicability. In addition, limitations of all the GFA parameters will be discussed, and future focuses in quantifying GFA of metallic systems will also be suggested.

Authors:
 [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931932
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Intermetallics; Journal Volume: 15
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; METALLIC GLASSES; RELIABILITY; GLASS

Citation Formats

Lu, Zhao Ping, Bei, Hongbin, and Liu, Chain T. Recent progress in quantifying glass-forming ability of bulk metallic glasses. United States: N. p., 2007. Web. doi:10.1016/j.intermet.2006.10.017.
Lu, Zhao Ping, Bei, Hongbin, & Liu, Chain T. Recent progress in quantifying glass-forming ability of bulk metallic glasses. United States. doi:10.1016/j.intermet.2006.10.017.
Lu, Zhao Ping, Bei, Hongbin, and Liu, Chain T. Mon . "Recent progress in quantifying glass-forming ability of bulk metallic glasses". United States. doi:10.1016/j.intermet.2006.10.017.
@article{osti_931932,
title = {Recent progress in quantifying glass-forming ability of bulk metallic glasses},
author = {Lu, Zhao Ping and Bei, Hongbin and Liu, Chain T},
abstractNote = {The {gamma} parameter proposed by the authors has prompted a lot of new interests in quantifying glass-forming ability (GFA) of bulk metallic glasses (BMGs). As a result, many different GFA indicators/criteria have been suggested lately. Recent development in this area is summarized herein; it was found that all newly developed parameters can be grouped into three basic categories according to their definitions. Our statistical analysis, particularly the direct comparison with the {sigma} parameter developed by Park et al., shows that the universal GFA indicator ? is still the best in terms of reliability and applicability. In addition, limitations of all the GFA parameters will be discussed, and future focuses in quantifying GFA of metallic systems will also be suggested.},
doi = {10.1016/j.intermet.2006.10.017},
journal = {Intermetallics},
number = ,
volume = 15,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • No abstract prepared.
  • Due to their scientific significance and potential engineering applications, bulk metallic glasses are among the most intensively studied advanced materials. Understanding the glass-forming ability (GFA) of these metallic alloys is a long-standing subject. While a large number of empirical factors have been proposed to correlate with GFA of the alloys, a full understanding of GFA remains a goal to achieve. Since glass formation is a competing process against crystallization, we have performed a systematic analysis on the crystallization kinetics of two known best metallic glass-formers Pd{sub 40}Cu{sub 30}Ni{sub 10}P{sub 20} (in at. %) and Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5}more » based on classical nucleation and growth theory. Our results show that there is a dramatic difference between the two alloys in their nucleation behavior although they possess comparable GFA. Particularly, an extremely sharp nucleation peak ({approx}10{sup 18}/m{sup 3} s) is found for Pd{sub 40}Cu{sub 30}Ni{sub 10}P{sub 20} around 632 K with a very small half maximum width of 42 K, implying that this alloy is an excellent candidate for nanocrystallization studies. Moreover, we have also found that the GFA of these alloys can be calculated to a high accuracy and precision based on the classical theory, suggesting that the classical theory may be sufficient to account for glass formation mechanism in these metallic alloys.« less
  • Despite its importance, a thermodynamic approach to determining the glass-forming ability (GFA) of bulk metallic glass (BMG) remains a goal to be achieved. We examined the GFA of water-quenched Pd-P-based and Pt{sub 60}Ni{sub 15}P{sub 25} BMG's in which their molten alloys were sufficiently treated with a dehydrated B{sub 2}O{sub 3} flux prior to and during quenching to room temperature. This allowed us to envisage the applicability of the classical steady-state homogeneous nucleation theory because the suppression of heterogeneous nucleation worked effectively. GFA was examined by comparing the critical cooling rate R{sub c}{sup h} for glass formation with the maximum diametermore » d{sub max} of glass. To calculate R{sub c}{sup h}, the homogeneous nucleation rate I{sub ss}(T), and the growth rate u{sub c}(T) were estimated as functions of the undercooling temperature of molten alloys. Then, the free energy difference {Delta}G{sub L-x}(T) between the liquid and crystalline phases, and the viscosity {eta}(T) of the liquid were experimentally determined while the surface energy {sigma}{sub sL}(T) at the liquid-nucleus interface was estimated by calculation. The d{sub max} of rod BMG's correlated strongly to R{sub c}{sup h} through the relation R{sub c}{sup h} {approx_equal}d{sub max}{sup -3}/10 mm{sup 3} Ks{sup -1}.« less
  • A convenient method is proposed for the measurement of the characteristic free volumes, viz., the amount of excess free volume annihilation in structural relaxation V{sub f-sr} and the amount of new free volume production in glass transition V{sub f-gt} of bulk metallic glasses (BMGs) by thermal dilation (DIL) test. Through the DIL tests, the characteristic free volumes are found to be sensitive to the change of glass forming ability (GFA). The Pd{sub 40}Cu{sub 30}Ni{sub 10}P{sub 20} BMG has a quite small V{sub f-sr}. For a series of Fe-Cr-Mo-C-B-(Er) BMGs, Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 2} with the largest GFAmore » is identified to have the largest V{sub f-gt} and smallest V{sub f-sr}. The correlation between V{sub f-sr} and the squares of critical diameters of these iron-based BMGs can be fitted as a negative exponential function with high accuracy.« less
  • When a liquid is cooled well below its melting temperature at a rate that exceeds the critical cooling rate R{sub c}, the crystalline state is bypassed and a metastable, amorphous glassy state forms instead. R{sub c} (or the corresponding critical casting thickness d{sub c}) characterizes the glass-forming ability (GFA) of each material. While silica is an excellent glass-former with small R{sub c} < 10{sup −2} K/s, pure metals and most alloys are typically poor glass-formers with large R{sub c} > 10{sup 10} K/s. Only in the past thirty years have bulk metallic glasses (BMGs) been identified with R{sub c} approachingmore » that for silica. Recent simulations have shown that simple, hard-sphere models are able to identify the atomic size ratio and number fraction regime where BMGs exist with critical cooling rates more than 13 orders of magnitude smaller than those for pure metals. However, there are a number of other features of interatomic potentials beyond hard-core interactions. How do these other features affect the glass-forming ability of BMGs? In this manuscript, we perform molecular dynamics simulations to determine how variations in the softness and non-additivity of the repulsive core and form of the interatomic pair potential at intermediate distances affect the GFA of binary alloys. These variations in the interatomic pair potential allow us to introduce geometric frustration and change the crystal phases that compete with glass formation. We also investigate the effect of tuning the strength of the many-body interactions from zero to the full embedded atom model on the GFA for pure metals. We then employ the full embedded atom model for binary BMGs and show that hard-core interactions play the dominant role in setting the GFA of alloys, while other features of the interatomic potential only change the GFA by one to two orders of magnitude. Despite their perturbative effect, understanding the detailed form of the intermetallic potential is important for designing BMGs with cm or greater casting thickness.« less