Stress–strain behaviors of Ti-based bulk metallic glass and their nanostructures

2007 ◽  
Vol 22 (5) ◽  
pp. 1406-1413 ◽  
Author(s):  
T. Ohkubo ◽  
D. Nagahama ◽  
T. Mukai ◽  
K. Hono
Keyword(s):  
Plastic Strain ◽  
Metallic Glasses ◽  
Volume Fraction ◽  
Bulk Metallic Glasses ◽  
Three Dimensional ◽  
Atom Probe ◽  
Stress Strain ◽  
Annealing Conditions ◽  
Transmission Electron ◽  
Mold Casting

We have investigated the compression stress–strain behaviors of Ti40Zr25Cu12Ni3Be20 bulk metallic glasses prepared by Cu mold casting from various melt temperatures. Plastic strain was found to vary sensitively on the temperature of melts and subsequent annealing conditions. To understand the origin of the plasticity change, the microstructures were characterized using transmission electron microscopy and a laser-assisted three-dimensional atom probe. The fully amorphous sample cast from 1273 K showed 0.6% plastic strain, and it was enhanced to 1.3% after isothermal annealing at 573 K. The sample cast from 1423 K showed 3.0% plastic strain, from which the presence of nanocrystals with a volume fraction of about 12% was confirmed. The sample cast from a higher temperature (1573 K) contained a larger fraction of crystals, which showed limited plastic strain. The effect of the volume fraction of the nanocrystals on the plasticity of bulk metallic glasses is discussed based on the experimental results.

Effect of Sn on Glass Formation Ability and Crystallization Behaviors of Cu-Based Bulk Metallic Glass Alloy

2010 ◽  
Vol 139-141 ◽  
pp. 102-106 ◽  
Author(s):  
Deng Wei Zhang ◽  
Xin Ying Teng ◽  
Bo Li ◽  
Wen Jie Zhang
Keyword(s):  
Metallic Glasses ◽  
Volume Fraction ◽  
Bulk Metallic Glasses ◽  
Activation Energies ◽  
Continuous Heating ◽  
Heating Rates ◽  
Crystallization Behaviors ◽  
Characteristic Temperatures ◽  
Mold Casting ◽  
Crystallization Volume

Cu-based bulk metallic glasses (BMGs) with 5 mm in diameter were synthesized by copper mold casting. The effects of tin (Sn) addition on glass-forming ability (GFA), thermal stability of BMGs were investigated. It was found the addition of 4 at. % Sn is effective for an increase in GFA. The crystallization behaviors of Cu-based bulk metallic glasses during continuous heating are investigated mainly by differential scanning calorimeter(DSC).The results show that the characteristic temperatures(Tg,Tx and Tp) shifted to high temperature region with increasing of heating rates. The activation energies Eg, Ex and Ep, corresponding to characteristic temperatures Tg, Tx, and Tp, respectively, were obtained from Kissinger and Ozawa equations. The calculated activation energies agree well with Kissinger or Ozawa equations due to the almost invariability of the crystallization volume fraction at the characteristic temperatures for different heating rates.

Effect of Minor Addition of Noble Elements on Microstructure and Mechanical Properties of Ti-Based Bulk Metallic Glasses

2011 ◽  
Vol 148-149 ◽  
pp. 241-244 ◽  
Author(s):  
Feng Xiang Qin ◽  
Guo Qiang Xie ◽  
Zhen Hua Dan ◽  
Akihisa Inoue
Keyword(s):  
Mechanical Properties ◽  
Plastic Strain ◽  
Shear Band ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
High Strength ◽  
Copper Mold ◽  
Copper Mold Casting ◽  
Minor Addition ◽  
Mold Casting

Ti-based bulk metallic glasses with minor addition of Ag, Au or Pt elements were prepared by copper mold casting. The Microstructure of the as-cast samples was examined by TEM. Nanoparticles identified as cubic Pd3Ti with crystal planes of (111), (200), (220) and (311) are observed in all the alloys modified by the minor addition of Ag, Au or Pt. The results revealed that the glassy/nanoparticle composited alloys exhibited high strength about 2000 MPa and plastic strain between 1.5-10% due to the inhibition of propagation of shear band.

Effect of Additional Irradiation at Different Fluxes on RPV Embrittlement

2009 ◽  
Author(s):  
Kenji Dohi ◽  
Kenji Nishida ◽  
Akiyoshi Nomoto ◽  
Naoki Soneda ◽  
Hiroshi Matsuzawa ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Solute Atom ◽  
Volume Fraction ◽  
Neutron Fluence ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atom Clusters ◽  
Neutron Fluences ◽  
The Difference ◽  
Test Reactor

The effect of the neutron flux at high fluence on the microstructural and hardness changes of a reactor pressure vessel (RPV) steel was investigated. An accelerated test reactor irradiation of a RPV material, previously irradiated in commercial reactors, was carried out at the lowest possible neutron fluxes in order to obtain neutron fluences up to approximately 1×1020 n/cm2 (E>1MeV). State-of-the-art experimental techniques such as three-dimensional atom probe were applied to carry out advanced quantitative characterization of defect features in the materials. Results for the same material irradiated in both high and low flux conditions are compared. For neutron fluences above 6×1019 n/cm2 (E>1MeV) the difference in the neutron fluence dependence of the increase in hardness is not seen for any neutron flux condition. The volume fraction of solute atom clusters increases linearly with neutron fluence, and the influence of neutron flux is not significant. The component elements and the chemical composition of the solute atom clusters formed by the irradiation do not change regardless of the neutron fluence and flux. The square root of the volume fraction of the solute atom clusters is a good correlation with the increase in hardness.

Effect of Minor Addition Ta on the Thermal Stability and Corrosion Resistance of Ti-Zr-Cu-Pd Bulk Metallic Glasses

2013 ◽  
Vol 750 ◽  
pp. 23-26 ◽  
Author(s):  
Feng Xiang Qin ◽  
Guo Qiang Xie ◽  
Sheng Li Zhu ◽  
Zhen Hua Dan
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Metallic Glasses ◽  
Anodic Polarization ◽  
Volume Fraction ◽  
Bulk Metallic Glasses ◽  
Large Plastic Deformation ◽  
Minor Addition ◽  
Proper Volume

In this research, the effect of Ta addition on the formation, thermal stability and corrosion behavior of Ti-Zr-Cu-Pd bulk metallic glasses were investigated. The results revealed with minor addition of Ta, higher corrosion resistance and compressive strength as well as large plastic deformation were achieved. Minor addition Ta is effective for the formation of more protectively passive film during the process of anodic polarization. In addition, proper volume fraction nanoparticle with small size is responsible for the large plastic deformation of the as-cast Ti-based bulk metallic glasses with 1% Ta addition.

Improved Synthesis of Bulk Metallic Glasses by Current-Assisted Copper Mold Casting

2010 ◽  
Vol 13 (1-2) ◽  
pp. 38-42 ◽  
Author(s):  
Mihai Stoica ◽  
Andràs Bàrdos ◽  
Stefan Roth ◽  
Lajos K. Varga ◽  
Ludwig Schultz ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Copper Mold ◽  
Copper Mold Casting ◽  
Mold Casting

Effect of Cu On Microstructural Evolution of Nanocrystalline Soft and Hard Magnetic Materials

1999 ◽  
Vol 577 ◽  
Author(s):  
K. Hono ◽  
D. H. Ping ◽  
S. Hirosawa
Keyword(s):  
Amorphous Alloys ◽  
Three Dimensional ◽  
Atom Probe ◽  
Hard Magnetic Materials ◽  
Atom Clusters ◽  
Transmission Electron ◽  
Nucleation Sites ◽  
Final Microstructure ◽  
Crystallization Reaction ◽  
Primary Crystals

ABSTRACTThe nanocrystallization processes in Fe-Si-B-Nb-Cu and Fe-Nd-B(-Cu-Nb) amorphous alloys have been studied by transmission electron microscopy (TEM) and a three dimensional atom probe (3DAP). Cu additions are effective in refining the nanocrystalline microstructures of both alloys, because Cu atom clusters formed prior to the crystallization reaction serve as heterogeneous nucleation sites for the primary crystals. However, the clustering behaviors of Cu atoms in these two alloy systems are different, i.e., Cu completely dissolves in the Nd2Fe1 4B phase in the final microstructure of the Nd4.5Fe75.8B18.5Cu0.2Nb1 alloy, whereas CL' clusters grow to fcc-Cu particles in the Fe73.5Si13.5B9Nb3Cu1 alloy. The nanocrystallization processes in these two alloys clarified by the 3DAP results are compared.

Atom Probe Microscopy and its Future

1994 ◽  
Vol 332 ◽  
Author(s):  
T. F. Kelly ◽  
P. P. Camus ◽  
D. J. Larson ◽  
L. M. Holzman
Keyword(s):  
Materials Science ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Level ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Probe Field ◽  
Transmission Electron ◽  
Indispensable Tool ◽  
3D Information

ABSTRACTMuch of the current activity and excitement in materials science involves processing and understanding materials at the atomic scale. Accordingly, it is necessary for materials scientists to control and characterize materials at the atomic level. There are only a few microscopies that are capable of providing information about the structure of materials at the atomic level: the atom probe field ion microscope, the high resolution transmission electron microscope, and the scanning tunneling microscope. The three-dimensional atom probe (3DAP) determines the 3D location and elemental identity of each atom in a sample. It is the only technique that provides 3D information at the atomic scale.The origin and underlying concepts behind the 3DAP are described. Several examples of actual images from existing 3DAPs are shown with emphasis on nanometer-scale analysis. Current limitations of the technique and expected future developments in this form of microscopy are described. It is our opinion that 3D atomic-scale imaging will be an indispensable tool in materials science in the coming decades.

Thermal stability, corrosion resistance, and surface analysis of Cu–Hf–Ti–Ni–Nb bulk metallic glasses

2009 ◽  
Vol 24 (2) ◽  
pp. 316-323 ◽  
Author(s):  
C.L. Qin ◽  
W. Zhang ◽  
K. Asami ◽  
N. Ohtsu ◽  
A. Inoue
Keyword(s):  
Thermal Stability ◽  
Corrosion Resistance ◽  
Metallic Glasses ◽  
Surface Film ◽  
Bulk Metallic Glasses ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Copper Mold Casting ◽  
Mold Casting

Bulk metallic glasses (BMGs) with high thermal stability and good corrosion resistance were synthesized in the (Cu0.6Hf0.25Ti0.15)100−x−yNiyNbx system by copper mold casting. The addition of Ni element causes an extension of a supercooled liquid region (ΔTx = Tx – Tg) from 60 K for Cu60Hf25Ti15 to 70 K for (Cu0.6Hf0.25Ti0.15)95Ni5. The simultaneous addition of Ni and Nb to the alloy is effective in improving synergistically the corrosion resistance in 1 N HCl, 3 mass% NaCl, and 1 N H2SO4 + 0.01 N NaCl solutions. The highly protective Hf-, Ti-, and Nb-enriched surface film is formed by the rapid initial preferential dissolution of Cu and Ni, which is responsible for the high corrosion resistance of the alloys in the solutions examined.

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