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Title: Unified equation for the strength of bulk metallic glasses

Abstract

In the present study, a conceptual approach to evaluate the strength of metallic glass systems is proposed from a free-volume point of view. Based on the physical analogy between the plastic deformation and glass transition, the strength of amorphous structures was found to depend on both the localized shear mechanism and the atomic cohesive energy. Interestingly, we find that the strength at the ambient temperature (T0) can be determined by the glass transition temperature (Tg) and molar volume (V), and can be specifically predicted by a unified parameter of (Tg-T0)/V. The predicted strength was unambiguously verified from experimental data reported for a number of metallic glass systems.

Authors:
 [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); High Temperature Materials Laboratory
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
989673
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 22
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AMBIENT TEMPERATURE; DEFORMATION; GLASS; METALLIC GLASSES; PLASTICS; SHEAR; TRANSITION TEMPERATURE

Citation Formats

Nieh, Tai-Gang, Liu, Chain T, and Yang, Bing. Unified equation for the strength of bulk metallic glasses. United States: N. p., 2006. Web.
Nieh, Tai-Gang, Liu, Chain T, & Yang, Bing. Unified equation for the strength of bulk metallic glasses. United States.
Nieh, Tai-Gang, Liu, Chain T, and Yang, Bing. Mon . "Unified equation for the strength of bulk metallic glasses". United States. doi:.
@article{osti_989673,
title = {Unified equation for the strength of bulk metallic glasses},
author = {Nieh, Tai-Gang and Liu, Chain T and Yang, Bing},
abstractNote = {In the present study, a conceptual approach to evaluate the strength of metallic glass systems is proposed from a free-volume point of view. Based on the physical analogy between the plastic deformation and glass transition, the strength of amorphous structures was found to depend on both the localized shear mechanism and the atomic cohesive energy. Interestingly, we find that the strength at the ambient temperature (T0) can be determined by the glass transition temperature (Tg) and molar volume (V), and can be specifically predicted by a unified parameter of (Tg-T0)/V. The predicted strength was unambiguously verified from experimental data reported for a number of metallic glass systems.},
doi = {},
journal = {Applied Physics Letters},
number = 22,
volume = 88,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2006},
month = {Mon May 01 00:00:00 EDT 2006}
}
  • For production of micro components in large numbers, forging is an interesting and challenging process. The conventional metals like silver, steel and aluminum often require multi-step processes, but high productivity and increased strength justify the investment. As an alternative, bulk metallic glasses will at elevated temperatures behave like a highly viscous liquid, which can easily form even complicated geometries in 1 step. The strengths and limitations of forming the 2 materials are analyzed for a micro 3D component in a silver alloy and an Mg-Cu-Y BMG.
  • Results of calorimetric, differential thermal analysis, and structural measurements are presented for a series of bulk metallic glass forming compositions in the Zr[endash]Ti[endash]Cu[endash]Ni[endash]Be alloy system. The calorimetric data for five alloys, prepared along the tie line between phase separating and nonphase separating compositions, show that the transition from phase separating to nonphase separating behavior is smooth. The bulk glasses near the center of the tie line exhibit large supercooled liquid regions: [Delta]T[approx]135 K, the largest known for a bulk metallic glass. [copyright] [ital 1999 American Institute of Physics.]
  • Formation of bulk metallic glass in quaternary Ti--Zr--Cu--Ni alloys by relatively slow cooling from the melt is reported. Thick strips of metallic glass were obtained by the method of metal mold casting. The glass forming ability of the quaternary alloys exceeds that of binary or ternary alloys containing the same elements due to the complexity of the system. The best glass forming alloys such as Ti{sub 34}Zr{sub 11}Cu{sub 47}Ni{sub 8} can be cast to at least 4-mm-thick amorphous strips. The critical cooling rate for glass formation is of the order of 250 K/s or less, at least two orders ofmore » magnitude lower than that of the best ternary alloys. The glass transition, crystallization, and melting behavior of the alloys were studied by differential scanning calorimetry. The amorphous alloys exhibit a significant undercooled liquid region between the glass transition and first crystallization event. The glass forming ability of these alloys, as determined by the critical cooling rate, exceeds what is expected based on the reduced glass transition temperature. It is also found that the glass forming ability for alloys of similar reduced glass transition temperature can differ by two orders of magnitude as defined by critical cooling rates. The origins of the difference in glass forming ability of the alloys are discussed. It is found that when large composition redistribution accompanies crystallization, glass formation is enhanced. The excellent glass forming ability of alloys such as Ti{sub 34}Zr{sub 11}Cu{sub 47}Ni{sub 8} is a result of simultaneously minimizing the nucleation rate of the competing crystalline phases. The ternary/quaternary Laves phase (MgZn{sub 2} type) shows the greatest ease of nucleation and plays a key role in determining the optimum compositions for glass formation. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less
  • In 1993, a new beryllium bearing bulk metallic glass with the nominal composition of Zr{sub 41.25}Ti{sub 13.75}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} was discovered at Caltech. This metallic glass can be cast as cylindrical rods as large as 16 mm in diameter, which permitted specimens to be fabricated with geometries suitable for dynamic testing. For the first time, the dynamic compressive yield behavior of a metallic glass was characterized at strain rates of 10{sup 2} to 10{sup 4}/s by using the split Hopkinson pressure bar. A high-speed infrared thermal detector was also used to determine if adiabatic heating occurred during dynamic deformationmore » of the metallic glass. From these tests it appears that the yield stress of the metallic glass is insensitive to strain rate and no adiabatic heating occurs before yielding. {copyright} {ital 1996 Materials Research Society.}« less
  • Results of calorimetric, differential thermal analysis, and structural measurements are presented for a series of bulk metallic glass forming compositions in the Zr{endash}Ti{endash}Cu{endash}Ni{endash}Be alloy system. The calorimetric data for five alloys, prepared along the tie line between phase separating and nonphase separating compositions, show that the transition from phase separating to nonphase separating behavior is smooth. The bulk glasses near the center of the tie line exhibit large supercooled liquid regions: {Delta}T{approx}135 K, the largest known for a bulk metallic glass. {copyright} {ital 1999 American Institute of Physics.}