共查询到20条相似文献,搜索用时 11 毫秒
1.
W. Zheng Y. J. Huang G. Y. Wang P. K. Liaw J. Shen 《Metallurgical and Materials Transactions A》2011,42(6):1491-1498
The compressive-deformation behavior of the Zr50.7Cu28Ni9Al12.3 bulk metallic glass (BMG) was investigated over a wide strain-rate range at room temperature. The yield strength of the BMG
studied is independent of the strain rates applied upon quasi-static loading; however, it decreases remarkably upon dynamic
loading. Serrated flows and shear bands appear at low quasi-static strain rates; nevertheless, they vanish as the strain rate
increases to 1.0 × 10−1 s−1. Cracks appearing on the side surface of the fractured sample after dynamic compression yield a strain-accommodation deformation
mechanism upon dynamic loading. Scanning electron microscopy observations reveal that molten liquids increase on the fractured
surfaces with increasing strain rate, indicating that adiabatic heating in the shear bands is enhanced as the strain rate
increases. 相似文献
2.
Fe-based bulk metallic glasses (amorphous metals) have been developed, and several compositions are shown to have excellent
corrosion resistance in chloride solutions. Further, thermal-spray amorphous metals are being developed for use as a barrier
coating layer, to protect substrate materials from corrosion. Galvanic action between dissimilar metals and the coating/substrate
for the amorphous-alloy coatings is of practical interest for a number of applications. The mixed-potential theory provides
a useful approach for examining the corrosion behavior of the component materials in the galvanic couple and is applied in
this study. Galvanic action was studied for an Fe-based structurally amorphous metal (SAM) 1651 and several crystalline alloys
that included 1018 C-steel, stainless steel (SS) 316L, and alloy 22. Anodic and cathodic polarization curves of each of the
metals were measured by potentiodynamic polarization. Based on the mixed-potential theory, the behavior of the component materials
in a galvanic cell was predicted. The predictions are compared to the measured behavior of galvanic couples with the crystalline
alloys.
This article is based on a presentation given in the symposium entitled “Iron-Based Amorphous Metals: An Important Family
of High-Performance Corrosion-Resistant Materials,” which occurred during the MSandT meeting, September 16–20, 2007, in Detroit,
Michigan, under the auspices of The American Ceramics Society (ACerS), The Association for Iron and Steel Technology (AIST),
ASM International, and TMS. 相似文献
3.
4.
George Sunny Vikas Prakash John J. Lewandowski 《Metallurgical and Materials Transactions A》2013,44(10):4644-4653
In the present study, dynamic fracture experiments are performed on fully amorphous Liquidmetal-1 (LM-1), a Zr-based BMG, to better understand fracture initiation and propagation in notched specimens. Experiments are conducted on notched (110 μm notch radius) four-point bend specimens using an instrumented modified split-Hopkinson pressure bar apparatus. The results of these experiments suggest that the critical dynamic stress intensity factor achieved by the notched LM-1 specimens is ~110 MPa m1/2, which is similar to the fracture toughness determined from previous quasi-static fracture experiments. This insensitivity of the fracture toughness to crack tip loading rate suggests negligible loading-rate sensitivity on the dynamic fracture initiation toughness in LM-1. In situ high-speed camera images of the notched sample during the dynamic loading process show multiple fracture initiation attempts and subsequent arrests prior to catastrophic fracture initiation. Controlled stress wave loading experiments designed to induce sub-critical levels of damage in the notched specimens show extensive deformation banding extending 150 to 200 μm outward from the notch. The deformation bands, nominally perpendicular to each other, run along the direction of the notch and perpendicular to it. They are consistent with slip-line fields in notched samples of elastic perfectly plastic materials. Subsequent loading of the damaged specimen again shows several attempts at crack initiation followed by blunting; the initial sub-critical damage in the region around the notch is understood to increase the energy required for catastrophic specimen failure and is consistent with an increase in the effective notch radius due to preexisting damage. 相似文献
5.
J. L. Cheng G. Chen H. W. Xu F. Xu Y. L. Du 《Metallurgical and Materials Transactions A》2012,43(8):2620-2624
The microstructural evolution was experimentally studied at a withdrawal velocity between 6 and 0.1?mm/s by a Bridgman technique in Zr51.7Cu30Ni8.3Al10. Our results indicate that the Zr51.7Cu30Ni8.3Al10 alloy can be considered as the ZrCu-Zr2Cu pseudo-binary eutectic system, and the glass-forming ability (GFA) is correlated with the (L ?? ZrCu?+?Zr2Cu) pseudo-binary eutectic reaction. This understanding has important implications and guidance for designing and fabricating new Zr-Cu-Ni-Al bulk metallic glasses (BMGs) with superior glass formation. Moreover, compressive tests were also performed on these samples. The results show that as the precipitation of crystal, plastic strain decreases. It indicates that the precipitated crystal cannot block the fast propagation of the localized shear bands and the macroscopically brittle failure. 相似文献
6.
A.H. Vormelker O.L. Vatamanu L. Kecskes J.J. Lewandowski 《Metallurgical and Materials Transactions A》2008,39(8):1922-1934
The effects of changes in test temperature (20 °C, 260 °C, 330 °C, and 380 °C), strain rate (10−5 to 10−1 s−1), and loading conditions (displacement control vs loading-rate control) on the tensile behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 (LiquidMetal 1 (LM1)), a bulk metallic glass (BMG), have been determined. Significant effects of the test temperature, strain
rate, and loading condition were observed on the strength, ductility/elongation, and mechanisms of failure (shear, ductile
rupture, etc.). This material exhibited extensive elongation (i.e., >100 pct) prior to failure when tested near the glass transition temperature (T
g
≈ 375 °C) at sufficiently low strain rates, while higher strain rates or lower test temperatures produced shear fracture
at low elongation. The flow and fracture behavior was also significantly affected by the loading condition (i.e., displacement vs loading-rate control). The effective strain rate necessary to cause failure in shear without significant global flow was
several orders of magnitude lower in loading-rate control than in displacement control. Samples exhibiting high elongation
tested in displacement control gently and convexly drew to a near point (i.e., ductile rupture). Samples tested at the same temperature exhibiting high elongation in loading-rate control rapidly and
concavely necked, followed by drawing to a constant diameter “wire” (i.e., ductile drawing), eventually failing by nearly pure ductile rupture. All samples that displayed significant elongation
did so inhomogeneously, and were characterized by non-Newtonian global flow.
This article is based on a presentation given in the symposium entitled “Bulk Metallic Glasses IV,” which occurred February
25–March 1, 2007 during the TMS Annual Meeting in Orlando, Florida under the auspices of the TMS/ASM Mechanical Behavior of
Materials Committee.
相似文献
J.J. Lewandowski ( Leonard Case Jr. Professor of Engineering)Email: |
7.
Laser processing is a precision manufacturing technique capable of producing materials with highly nonequilibrium microstructures.
Due to the localized heat input and high cooling rate inherent to the process, this technology is attractive for the production
of metallic glasses. In the present work, we use a laser deposition process to deposit a Zr-based metallic glass forming powder
on both amorphous and crystalline substrates of the same nominal composition. Amorphous melt zones are observed surrounded
by distinct crystalline heat-affected zones (HAZs). Detailed examination of the HAZ in the glassy substrates reveals the formation
of microscale spherulites, in contrast to the nanocrystalline phases observed following crystallization by isothermal annealing
of the glass at the crystallization temperature as well as in the HAZ of the crystalline substrates. The spherulites have
a different crystal morphology and structure from the nanocrystalline phases, indicating that the more stable nanocrystalline
phases are completely bypassed when the glass is devitrified at the higher heating rate. Reducing the heat input during laser
processing results in the near elimination of the crystalline HAZ in the amorphous substrates, suggesting that a critical
heating rate range is required to avoid devitrification. 相似文献
8.
M. Martin T. Sekine T. Kobayashi L. Kecskes N.N. Thadhani 《Metallurgical and Materials Transactions A》2007,38(11):2689-2696
The high stress U
s
-U
p
Hugoniot equation of state (EOS) of a zirconium-based bulk metallic glass (BMG, Zr57Nb5Cu15.4Ni12.6Al10) was determined using plate impact experiments on disk-shaped samples of 10-mm diameter and 2-mm thickness. The National
Institute for Materials Science (NIMS) two-stage light-gas gun was used for the high stress measurements (∼26 to 123 GPa),
and the Georgia Institute of Technology (GT) single-stage gas gun was used for the lower stress measurements (∼5 to 26 GPa).
The NIMS experiments were instrumented with streak photography and used the inclined mirror (IM) method to simultaneously
measure shock velocity and free surface velocity. The GT experiments used polyvinylidene fluoride (PVDF) stress gages and
velocity interferometry (VISAR) to simultaneously measure the shock velocity, free surface velocity, and stress. Results from
the streak camera records and PVDF gages + VISAR traces, as well as impedance matching calculations, were used to generate
the U
s
-U
p
Hugoniot EOS for the BMG over a wide range of stresses. The U
s
-U
p
data show evidence of a low pressure phase, a transition to a mixed phase region at ∼26 GPa, followed by transition at ∼67 GPa
to a high-pressure phase of bulk modulus of 288 GPa.
This article is based on a presentation made in the symposium entitled “Dynamic Behavior of Materials,” which occurred during
the TMS Annual Meeting and Exhibition, February 25–March 1, 2007 in Orlando, Florida, under the auspices of The Minerals,
Metals and Materials Society, TMS Structural Materials Division, and TMS/ASM Mechanical Behavior of Materials Committee. 相似文献
9.
10.
11.
12.
C. C. Yuan X. X. Xia K. H. Jiang D. Q. Zhao X. K. Xi 《Metallurgical and Materials Transactions A》2013,44(2):819-826
Damage tolerance (toughness and plasticity) properties of a ZrCuNiAl bulk metallic glass (BMG) are tailored through Sn alloying under ambient conditions. The result shows that the measured fracture energy is clearly correlated with the product (R) of Young’s modulus and averaged size of vein patterns on mode I crack surfaces of these BMGs. The implications of the current result on other BMGs are also briefly discussed, which might be useful for the evaluation of damage tolerance of tough BMGs. 相似文献
13.
Ionic Conductivity of Nano-LaF_3 Bulk Material at Room Temperature 相似文献
14.
《钢铁研究学报(英文版)》2016,(1):69-73
The effect of electropulsing treatment (EPT)on the microstructure of a Ti-based bulk metallic glass (BMG)has been studied.The maximum current density applied during EPT can exert a crucial role on tuning the microstructure of the BMG.When the maximum current density is no more than 2 720 A/mm2 ,the samples retains amorphous nature,whereas,beyond that,crystalline phases precipitate from the glassy matrix.During EPT,the maximum temperature within the samples EPTed at the maximum current densities larger than 2 720 A/mm2 is higher than the crystallization temperature of the BMG,leading to the crystallization event. 相似文献
15.
H.-J. Jun K.S. Lee J. Eckert Y.W. Chang 《Metallurgical and Materials Transactions A》2008,39(8):1831-1837
The deformation behavior of a monolithic Zr55Cu30Al10Ni5 (at. pct) bulk metallic glass (BMG) fabricated by suction casting has been investigated at elevated temperatures in this
study. A series of compression tests has been performed in the supercooled liquid temperature region. In the homogeneous flow
regime, this alloy exhibited a transition from the Newtonian to non-Newtonian flow depending upon both the strain rate and
the temperature. These two flow modes were then described by applying the Newtonian viscous flow theory and the transition
state theory, respectively. On the basis of a dynamic materials model (DMM), a processing map could successfully be constructed
to estimate the feasible forming conditions for this BMG alloy. Imaginary laboratory-scale extrusion tests were also performed
to determine solid-to-solid formability, and the results from both the finite element method (FEM)-based simulation and processing
map were then compared and discussed.
This article is based on a presentation given in the symposium entitled “Bulk Metallic Glasses IV,” which occurred February
25–March 1, 2007 during the TMS Annual Meeting in Orlando, Florida under the auspices of the TMS/ASM Mechanical Behavior of
Materials Committee. 相似文献
16.
17.
《钢铁研究学报(英文版)》2016,(11):1200-1205
The corrosion behavior study was conducted on a novel Fe_(77)Mo_5P_9C_(7.5)B_(1.5)in-situ metallic glass matrix composite(MGMC).This composite sample was developed by introduction of bccα-Fe dendrites as reinforcing phase.The corrosion behavior of this composite was compared to its monolithic counterpart and other Fe-based alloys such as 304 Land 2304Lstainless steels.The corrosion resistance of MGMCs in H_2SO_4 solution shows inferior to that of other Fe-based alloys.Experiments suggest that Fe-BMGs samples possess better corrosion resistance property than that of Fe-MGMCs.The possible underlying reasons can be the inhomogeneity induced by the precipitation ofα-Fe dendrites in the MGMCs. 相似文献
18.
In this study, we conduct a combined experimental and micromechanical investigation into the strain-rate sensitivity of concretes, with a special reference to the effect of aggregate concentration. We first measured the stress-strain relations of Type I portland cement with 0.45 water-to-cement ratio (w/c), and then those of the mortar containing sand aggregates of up to 50% volume concentration, over six orders of magnitude of strain rate, from 5×10?6/s to 1×10?1/s under compression. It was found that, at a given strain rate, the peak stress increases with the aggregate concentration but the peak strain tends to decrease with it. At a given aggregate concentration, the peak stress also increases with strain rate whereas the peak strain generally decreases with it. We then developed an inclusion-matrix type micromechanical model to simulate the behavior of the concrete. In this process the nonlinear viscoelastic behavior of the portland cement was modeled by a modified Burger's model with strain-rate dependent spring and dashpot elements, and the stress-strain relations of the mortar at various aggregate concentrations and strain rates were calculated from a two-phase composite model with a secant-moduli approach. It is shown that the measured data could be sufficiently well predicted by the developed micromechanics composite model. 相似文献
19.
Stefan Küchemann Hannes Wagner Moritz Schwabe Dennis Bedorf Walter Arnold Konrad Samwer 《Metallurgical and Materials Transactions A》2014,45(5):2389-2392
We investigated the effect of anelastic rearrangements in a Pd-based metallic glass during inhomogeneous plastic deformation producing shear bands at room temperature. Therefore, we subjected bulk metallic glasses to uniaxial stresses and characterized the influence of deformation on the global configurational energy state with ultrasonic and calorimetric methods. The results provide evidence that even in an inhomogeneous plastic deformation process at room temperature, a certain amount of energy can be stored which is thermally relaxed below the glass transition temperature. 相似文献
20.
Sung Hwan Hong Jeong Tae Kim Min Woo Lee Jin Man Park Min Ha Lee Bum Sung Kim Jun Young Park Yongho Seo Jin Yoo Suh Peng Yu Ma Qian Ki Buem Kim 《Metallurgical and Materials Transactions A》2014,45(5):2376-2381
We report on the formation of Ti-Cu-Ni-Zr-Sn-Si bulk metallic glass composites containing bimodal size of B2 TiCu compounds. The small B2 TiCu compound with a size of 1 to 10 μm has a strong influence on the oscillation of the shear stress, thus causing wavy propagation of the shear bands. In contrast, the large B2 TiCu compound with a size of 70 to 150 μm dissipates the shear stress by branching and multiplication of the shear bands. By forming the bimodal size of B2 TiCu compound, it is possible to determine the harmonic influence to further enhance the plasticity of the Ti-Cu-Ni-Zr-Sn-Si bulk metallic glass composites. 相似文献