Generalized Mohr-Coulomb strain criterion for bulk metallic glasses under complex compressive loading

Based on previous experimental results of the plastic dynamic analysis of metallic glasses upon compressive loading, a dynamical model is proposed. This model includes the sliding speed of shear bands in the plastically strained metallic glasses, the shear resistance of shear bands, the internal friction resulting from plastic deformation, and the influences from the testing machine. This model analysis quantitatively predicts that the loading rate can influence the transition of the plastic dynamics in metallic glasses from chaotic (low loading rate range) to stable behavior (high loading rate range), which is consistent with the previous experimental results on the compression tests of a Cu50Zr45Ti5 metallic glass. Moreover, we investigate the existence of a nonconstant periodic solution for plastic dynamical model of bulk metallic glasses by using Manásevich–Mawhin continuation theorem.

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Deformation and evolution of shear bands under compressive loading in bulk metallic glasses

Acta Materialia ◽

10.1016/j.actamat.2006.07.014 ◽

2006 ◽

Vol 54 (19) ◽

pp. 5271-5279 ◽

Cited By ~ 42

Author(s):

J.Y. Lee ◽

K.H. Han ◽

J.M. Park ◽

K. Chattopadhyay ◽

W.T. Kim ◽

...

Keyword(s):

Metallic Glasses ◽

Compressive Loading ◽

Shear Bands ◽

Bulk Metallic Glasses

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Effects of partial crystallization on compression and fatigue behavior of Zr-based bulk metallic glasses

Journal of Materials Research ◽

10.1557/jmr.2007.0059 ◽

2007 ◽

Vol 22 (2) ◽

pp. 493-500 ◽

Cited By ~ 9

Author(s):

G.Y. Wang ◽

P.K. Liaw ◽

Y. Yokoyama ◽

M. Freels ◽

R.A. Buchanan ◽

...

Keyword(s):

Metallic Glasses ◽

Amorphous Alloys ◽

Shear Fracture ◽

Fatigue Behavior ◽

Compressive Loading ◽

Bulk Metallic Glasses ◽

X Ray Diffraction ◽

Partial Crystallization ◽

Point Bend ◽

Fatigue Endurance

Zr50Cu40Al10, Zr50Cu30Al10Ni10, and Zr50Cu37Al10Pd3 (in at.%) are bulk metallic glasses (BMGs) with partial crystallization that were characterized by x-ray diffraction (XRD). The study of mechanical properties was conducted in compression at room temperature. Four-point-bend fatigue experiments were performed on the zirconium (Zr)-based BMGs in air. Under compressive loading, after the elastic deformation, no obvious plasticity occurred before the final shear fracture. The compression strengths are comparable to those of fully amorphous alloys. However, the fatigue-endurance limits of these BMGs were much lower than those of fully amorphous alloys. These results suggested that the fatigue behavior of a BMG is very sensitive to the microstructure, while the compression strength is not.

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Effect of Loading Rate on Failure in Bulk Metallic Glasses

MRS Proceedings ◽

10.1557/proc-754-cc6.2 ◽

2002 ◽

Vol 754 ◽

Author(s):

T. Jiao ◽

C. Fan ◽

L.J. Kecskes ◽

T.C. Hufnagel ◽

K.T. Ramesh

Keyword(s):

Metallic Glasses ◽

High Speed ◽

Dynamic Compression ◽

Failure Process ◽

Compressive Loading ◽

Shear Bands ◽

Bulk Metallic Glasses ◽

Experimental Results ◽

Dynamic Strain ◽

High Speed Photography

ABSTRACTWe have investigated failure in bulk metallic glass-forming alloys under dynamic compression. We implemented a recovery technique for the compression Kolsky bar to obtain dynamically deformed, intact specimens at various stages of deformation; this allows us to characterize the development of failure. We have also used high-speed photography to examine the failure process during the recovery experiments. The experimental results indicate that the failure under dynamic loading is somewhat different from that under quasi-static loading. Specimens subjected to quasistatic deformation developed multiple shear bands and substantial plastic deformations, while specimens subjected to dynamic (—strain rate ∼103 s-1) compressive loading fail by fracture along one dominant shear band. The mechanisms of dynamic failure in bulk metallic glasses are discussed on the basis of these experimental results.

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Mg-rich Mg–Ni–Gd ternary bulk metallic glasses with high compressive specific strength and ductility

Journal of Materials Research ◽

10.1557/jmr.2007.0034 ◽

2007 ◽

Vol 22 (2) ◽

pp. 334-338 ◽

Cited By ~ 31

Author(s):

E.S. Park ◽

H.J. Chang ◽

D.H. Kim

Keyword(s):

Metallic Glasses ◽

Compressive Loading ◽

Bulk Metallic Glasses ◽

Amorphous State ◽

High Strength ◽

Mixing Enthalpy ◽

Specific Strength ◽

Atom Pairs ◽

Wide Range ◽

Injection Casting

In the present study, we show by tailoring the combinations of the bonding energy among the elements in the liquid state, glass forming ability and compressive mechanical properties of the metallic glasses (MGs) can be improved. The mixing enthalpy values for binary atom pairs in the ternary Mg–Ni–Gd alloys (Mg–Ni: −12 kJ/mol, Mg–Gd: −27 kJ/mol, Ni–Gd: −161 kJ/mol) covers a wide range, although they are all negative. Mg-rich Mg–Ni–Gd (Mg > 70 at.%) alloys can be readily solidified into an amorphous state in a wide composition range up to 4 mm in diameter using the injection casting method; they exhibit the highest level of glass transition temperature Tg among those reported in Mg-based MGs so far. In particular, Mg-rich Mg–Ni–Gd bulk metallic glasses with 10–15 at.% Ni and 10–15 at.% Gd exhibit high strength over 900 MPa and large plastic strain up to ∼2% during compressive loading.

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Dynamic characterization of Cu–Zr binary bulk metallic glasses: A molecular dynamics study

Canadian Journal of Physics ◽

10.1139/cjp-2016-0926 ◽

2017 ◽

Vol 95 (12) ◽

pp. 1189-1193

Author(s):

Muhammad Imran ◽

Fayyaz Hussain ◽

Saba Altaf ◽

Abdul Rehman ◽

M. Arshad Javid ◽

...

Keyword(s):

Molecular Dynamics ◽

Metallic Glasses ◽

Compressive Loading ◽

Bulk Metallic Glasses ◽

Constant Strain Rate ◽

Anomalous Behavior ◽

Dynamics Simulation ◽

Embedded Atom ◽

Embedded Atom Method Potential

In the present study, a molecular dynamics simulation employing embedded atom method potential is performed to investigate the formation and characterization of CuZr bulk metallic glasses (BMGs). To elucidate the effect of component concentration of three samples of BMGs including Cu25Zr75, Cu50Zr50, and Cu75Zr25 that are formed by melt quenching. The local structure of BMGs is analyzed by means of radial distribution function and local atomic number density, ρ. The mechanical behavior of three compositions is investigated using uniaxial compressive loading at a constant strain rate. It is revealed from the results that yield strength increases with increasing Cu concentration. Thermal expansion of CuZr BMGs is examined and variation in length and volume is measured. The analysis revealed that Cu25Zr75, and Cu50Zr50 exhibited the typical expansion behavior while Cu75Zr25 showed an anomalous behavior.

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