scholarly journals EFFECT OF STRUCTURAL RELAXATION ON THE DEFORMATION BEHAVIOR OF A Zr64.13Cu15.75Ni10.12Al10 BULK METALLIC GLASS UNDER NANOINDENTATION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2320-2325 ◽  
Author(s):  
JIANSHENG GU ◽  
BINGCHEN WEI ◽  
TAIHUA ZHANG ◽  
YIHUI FENG ◽  
YANPING HU ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Deformation Behavior ◽  
Isothermal Annealing ◽  
Flow Behavior ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Obvious Effect ◽  
Dsc Curves

Structural relaxation by isothermal annealing below the glass transition temperature is conducted on a Zr 64.13 Cu 15.75 Ni 10.12 Al 10 bulk metallic glass. The effect of structural relaxation on thermal and mechanical properties was investigated by differential scanning calorimetry and instrumented nanoindentation. The recovery of the enthalpy in the DSC curves indicates that thermally unstable defects were annihilated through structural relaxation. During nanoindentation, the structural relaxation did not have a significant influence on the serrated plastic flow behavior. However, Structural relaxation shows an obvious effect in increasing both the hardness and elastic modulus, which is attributed to the annihilation of thermally unstable defects that resulted from the relaxation.

Influence of Structural Relaxation on Compressive Plasticity of Zr64.13Cu15.75Ni10.12Al10 Bulk Metallic Glass

2014 ◽  
Vol 910 ◽  
pp. 48-52 ◽  
Author(s):  
Jian Sheng Gu ◽  
Hui Feng Bo
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Structural Relaxation ◽  
Isothermal Annealing ◽  
Scanning Calorimetry

Structural relaxation through isothermal annealing below the glass transition temperature was conducted on a Zr64.13Cu15.75Ni10.12Al10bulk metallic glass. Differential scanning calorimetry was used to quantify enthalpy differences between the as-cast and relaxed samples, which were then related to average free volume differences. The influence of structural relaxation on plasticity was examined. While the free volume decreasement can be clearly observed between the as-cast and relaxed samples, structural relaxation is not accompanied by severe embrittlement.

scholarly journals Structural and Mechanical Characteristics of Cu50Zr43Al7 Bulk Metallic Glass Fabricated by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 775 ◽  
Author(s):  
Xiaoyang Lu ◽  
Mussokulov Nursulton ◽  
Yulei Du ◽  
Wenhe Liao
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Selective Laser Melting ◽  
Structural Relaxation ◽  
Mechanical Characteristics ◽  
X Ray Diffraction ◽  
Laser Melting ◽  
Scanning Calorimetry ◽  
Mold Casting ◽  
Induced Changes

In this work, the structural and mechanical characteristics of Cu50Zr43Al7 bulk metallic glass (BMG) fabricated by selective laser melting (SLM) are studied and the impacts from the SLM process are clarified. Cu50Zr43Al7 alloy specimens were manufactured by the SLM method from corresponding gas-atomized amorphous powders. The as-built specimens were examined in terms of phase structure, morphologies, thermal properties and mechanical behavior. The x-ray diffraction and differential scanning calorimetry results showed that structural relaxation and partial crystallization co-exist in the as-fabricated Cu50Zr43Al7 glassy samples. The nano- and micro- hardness and the elastic modulus of the SLM-fabricated Cu50Zr43Al7 BMG were higher than CuZrAl ternary BMGs with similar compositions prepared by conventional mold casting, which can be attributed to the structural relaxation in the former sample. However, the macro compressive strength of the SLM-fabricated Cu50Zr43Al7 BMG was only 1044 MPa mainly due to its porosity. This work suggests that the SLM process induced changes in structural and mechanical properties are significant and cannot be neglected in the fabrication of BMGs.

Structural Relaxation and Crystallization in a Pd40Cu30Ni10P20 Bulk Metallic Glass

2003 ◽  
Vol 806 ◽  
Author(s):  
R. Raghavan ◽  
U. Ramamurty ◽  
J. Basu ◽  
S. Ranganathan ◽  
N. Nishiyama
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Short Range ◽  
Annealing Temperature ◽  
Scanning Calorimetry ◽  
Short Range Ordering ◽  
The Stability

ABSTRACTThe stability of a Pd40Cu30Ni10P20 bulk metallic glass (BMG) against structural relaxation is investigated by isothermal and isochronal annealing heat treatments below and above its glass transition temperature, Tg, for varying periods. Differential scanning calorimetry (DSC) of the annealed samples shows an excess endotherm at Tg, irrespective of the annealing temperature. This recovery peak evolves exponentially with annealing time and is due to the destruction of anneal-induced compositional short range ordering. The alloy exhibits a high resistance to crystallization on annealing below Tg and complex Pd- and Ni-phosphides evolve on annealing above Tg.

scholarly journals Stability of ZrTiCuNiBe Bulk Metallic Glass upon Isothermal Annealing Near the Glass Transition Temperature

2002 ◽  
Vol 17 (6) ◽  
pp. 1385-1389 ◽  
Author(s):  
Wei Hua Wang ◽  
Ru Ju Wang ◽  
W. T. Yang ◽  
B. C. Wei ◽  
P. Wen ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Isothermal Annealing ◽  
Scanning Calorimetry ◽  
The Stability ◽  
Property Changes ◽  
Overlap Method

The stability of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) upon isothermal annealing near the glass transition temperature has been investigated by using x-ray diffraction, differential scanning calorimetry, and the pulse echo overlap method. The density, elastic constants, and thermodynamic parameters as well as their annealing time dependence have been determined. The microstructural and properties changes of the annealed BMG were checked by acoustic measurement. Obvious structural and property changes were observed with prolonged annealing of the BMG near the glass transition temperature.

scholarly journals Analysis of the Crystallization Kinetics and Thermal Stability of the Amorphous Mg72Zn24Ca4 Alloy

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3583
Author(s):  
Bartosz Opitek ◽  
Janusz Lelito ◽  
Michał Szucki ◽  
Grzegorz Piwowarski ◽  
Łukasz Gondek ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Amorphous Structure ◽  
Avrami Equation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Human Body Temperature ◽  
End Times

The aim of this study was to analyze the crystallization of the Mg72Zn24Ca4 metallic glass alloy. The crystallization process of metallic glass Mg72Zn24Ca4 was investigated by means of the differential scanning calorimetry. The glass-forming ability and crystallization are both strongly dependent on the heating rate. The crystallization kinetics, during the isothermal annealing, were modelled by the Johnson–Mehl–Avrami equation. Avrami exponents were from 2.7 to 3.51, which indicates diffusion-controlled grain growth. Local exponents of the Johnson–Mehl–Avrami equation were also calculated. In addition, the Mg phase—being the isothermal crystallization product—was found, and the diagram of the time–temperature phase transformation was developed. This diagram enables the reading of the start and end times of the crystallization process, occurring in amorphous ribbons of the Mg72Zn24Ca4 alloy on the isothermal annealing temperature. The research showed high stability of the amorphous structure of Mg72Zn24Ca4 alloy at human body temperature.

scholarly journals Effects of Annealing on Enthalpy Recovery and Nanomechanical Behaviors of a La-Based Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 579
Author(s):  
Ting Shi ◽  
Lanping Huang ◽  
Song Li
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Nanoindentation Measurement

Structural relaxation and nanomechanical behaviors of La65Al14Ni5Co5Cu9.2Ag1.8 bulk metallic glass (BMG) with a low glass transition temperature during annealing have been investigated by calorimetry and nanoindentation measurement. The enthalpy release of this metallic glass is deduced by annealing near glass transition. When annealed below glass transition temperature for 5 min, the recovered enthalpy increases with annealing temperature and reaches the maximum value at 403 K. After annealed in supercooled liquid region, the recovered enthalpy obviously decreases. For a given annealing at 393 K, the relaxation behaviors of La-based BMG can be well described by the Kohlrausch-Williams-Watts (KWW) function. The hardness, Young’s modulus, and serrated flow are sensitive to structural relaxation of this metallic glass, which can be well explained by the theory of solid-like region and liquid-like region. The decrease of ductility and the enhancement of homogeneity can be ascribed to the transformation from liquid-like region into solid-like region and the reduction of the shear transition zone (STZ).

scholarly journals Pressure-dependent flow behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass

2003 ◽  
Vol 18 (9) ◽  
pp. 2039-2049 ◽  
Author(s):  
Jun Lu ◽  
Guruswami Ravichandran
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Inelastic Deformation ◽  
Shear Failure ◽  
Flow Behavior ◽  
Shear Bands ◽  
Ductile Deformation ◽  
Multiaxial Compression ◽  
Dependent Flow ◽  
Tresca Criterion

An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

Structural and Phase Transformations During Crystallization of Pd43Ni10Cu27P20 Metallic Glass

2000 ◽  
Vol 644 ◽  
Author(s):  
Evgenia Pekarskaya ◽  
Jan Schroers ◽  
William L. Johnson
Keyword(s):  
Electron Microscopy ◽  
Amorphous Alloy ◽  
Metallic Glass ◽  
Temperature Region ◽  
Isothermal Annealing ◽  
P System ◽  
Scanning Calorimetry ◽  
Structural And Phase Transformations ◽  
Temperature Transformation ◽  
Nose Temperature

AbstractCrystallization of the Pd43Ni10Cu27P20 amorphous alloy during isothermal annealing in the undercooled temperature region is studied by electron microscopy and diffrential scanning calorimetry (DSC). It is established that different crystallization processes take place above and below the nose temperature of the time-temperature-transformation (TTT) diagram. Detailed analysis of the microstructural evolution at the early stages of the crystallization is performed. In addition, the stable phases in the Pd-Ni-Cu-P system are identified.

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