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81.
82.
"This paper discusses several factors that may explain [the] dynamic properties of internal labor migration. [The authors] focus especially on the influence of labor market and housing conditions on the mobility of people. A two-stage, generation-allocation model is proposed to investigate the role of different factors in the explanation of aggregate interregional migration flows. This model is applied to recent data on interprovincial labor migration in the Netherlands. The results indicate that housing supply seems to be an important determinant of temporal developments of spatial mobility, and that also the conditions on national and regional labor markets are associated with specific properties of recent migration patterns." 相似文献
83.
S. Y. Lee Y. L. Lu P. K. Liaw H. Choo S. A. Thompson J. W. Blust P. F. Browning A. K. Bhattacharya J. M. Aurrecoechea D. L. Klarstrom 《Mechanics of Time-Dependent Materials》2008,12(1):31-44
The creep–fatigue crack-growth tests of HASTELLOY® X alloy were carried out at the temperatures of 649°C, 816°C, and 927°C in laboratory air. The experiments were conducted under a constant stress-intensity-factor-range (ΔK) control mode with a R-ratio of 0.05. In the constant ΔK tests, a ΔK of 27.5 MPa\(\sqrt{\mathrm{m}}\) and a triangular waveform with a frequency of 0.333 Hz were used. Various tensile hold times at the maximum load were imposed to study fatigue and creep–fatigue interactions. Crack lengths were measured by a direct current potential drop method. In this paper, effects of hold time and temperature on the crack-growth rates are discussed. Furthermore, the crack-growth rates of the HASTELLOY® X alloy are compared to those of the HAYNES® 188 and HAYNES® 230® superalloys. 相似文献
84.
E-Wen Huang Rozaliya Barabash Nan Jia Yan-Dong Wang Gene E. Ice Bjørn Clausen J. Horton Peter K. Liaw 《Metallurgical and Materials Transactions A》2008,39(13):3079-3088
A combined experimental/computational approach is employed to study slip-system-related dislocation-substructure formation
during uniaxial tension of a single-phase, face-centered-cubic (fcc), nickel-based alloy. In-situ neutron-diffraction measurements were conducted to monitor the peak-intensity, peak-position, and peak-broadening evolution
during a displacement-controlled, monotonic-tension experiment at room temperature. The measured lattice-strain evolution
and the macrostress/macrostrain curves were used to obtain the material parameters required for simulating the texture development
by a visco-plastic self-consistent (VPSC) model. The simulated texture compared favorably with experimentally-determined texture
results over a range of 0 to 30 pct engineering strain. The grain-orientation-dependent input into the Debye-intensity ring
was considered. Grains favorably oriented relative to the two detector banks in the geometry of the neutron experiment were
indicated. For the favorably oriented grains, the simulated slip-system activity was used to calculate the slip-system-dependent,
dislocation-contrast factor. The combination of the calculated contrast factor with the experimentally-measured peak broadening
allows the assessment of the parameters of the dislocation arrangement within the specifically oriented grains, which has
a quantitative agreement with the transmission-electron-microscopy results.
This article is based on a presentation given in the symposium entitled “Neutron and X-Ray Studies for Probing Materials Behavior,”
which occurred during the TMS Spring Meeting in New Orleans, LA, March 9–13, 2008, under the auspices of the National Science
Foundation, TMS, the TMS Structural Materials Division, and the TMS Advanced Characterization, Testing, and Simulation Committee.
相似文献
Rozaliya Barabash (Research Professor)Email: |
85.
W. Kai T.H. Ho H.H. Hsieh Y.R. Chen D.C. Qiao F. Jiang G. Fan P.K. Liaw 《Metallurgical and Materials Transactions A》2008,39(8):1838-1846
The oxidation behavior of the Cu47.5Zr47.5Al5 (Cu3) and Cu47Ti34Zr11Ni8 (Cu4) bulk metallic glasses (BMGs) was studied over the temperature range of 400 °C to 500 °C in dry air. The oxidation kinetics
of both alloys generally followed a multistage parabolic-rate law, and the steady-state parabolic-rate constants (k
p
values) fluctuated with temperature for the Cu3 BMG, but increased with increasing temperature for the Cu4 BMG. The scales
formed on the BMGs were strongly dependent on the temperature and alloy composition, and were composed primarily of tetragonal-ZrO2 (t-ZrO2) and minor amounts of Al2O3, Cu2O, and CuO at 400 °C for the Cu3 BMG, while the monoclinic-ZrO2 (m-ZrO2) phase is present at T ≥ 425 °C, and the Cu2O phase is absent at 500 °C. Conversely, the scales formed on the Cu4 BMG consisted exclusively of CuO at 400 °C, while minor
amounts of t-ZrO2, TiO2, and ZrTiO4 formed at 425 °C to 450 °C, and TiO was also detected at higher temperatures. It was found that both amorphous Cu3 and Cu4
substrates transformed into different crystalline phases, and were strongly dependent on temperature and duration of time.
This article is based on a presentation given in the symposium entitled “Bulk Metallic Glasses IV,” which occurred during
the TMS Annual Meeting February 25–March 1, 2007, in Orlando, Florida under the auspices of the TMS/ASM Mechanical Behavior
of Materials Committee. 相似文献
86.
87.
A non-ideal model for predicting the effect of dissolved salt on the flash point of solvent mixtures
Flash point is one of the major quantities used to characterize the fire and explosion hazard of liquids. Herein, a liquid with dissolved salt is presented in a salt-distillation process for separating close-boiling or azeotropic systems. The addition of salts to a liquid may reduce fire and explosion hazard. In this study, we have modified a previously proposed model for predicting the flash point of miscible mixtures to extend its application to solvent/salt mixtures. This modified model was verified by comparison with the experimental data for organic solvent/salt and aqueous-organic solvent/salt mixtures to confirm its efficacy in terms of prediction of the flash points of these mixtures. The experimental results confirm marked increases in liquid flash point increment with addition of inorganic salts relative to supplementation with equivalent quantities of water. Based on this evidence, it appears reasonable to suggest potential application for the model in assessment of the fire and explosion hazard for solvent/salt mixtures and, further, that addition of inorganic salts may prove useful for hazard reduction in flammable liquids. 相似文献
88.
R.V. Steward G. Wang R.A. Buchanan P.K. Liaw T.A. Saleh D.L. Klarstrom S.N. Meck 《Metallurgical and Materials Transactions A》2007,38(13):2226-2234
The HASTELLOY C2000 superalloy is a commercially designed superalloy manufactured to function in reducing and oxidizing corrosive
solutions. The industrial applications have tremendous potential in automotive, structural, aviation, and storage components.
Although C2000 demonstrates good reducing and oxidizing traits in extremely aggressive media (which are attractive features
of its chemistry), changes in the mechanical properties are believed to be insignificant due to its strong propensity to passivate
under corrosive conditions. The ductility behavior and corrosion properties of C2000 are superior to those of stainless steels.
The objective of the present study is to examine the corrosion-fatigue behavior of C2000 in a 3.5 wt pct sodium-chloride (NaCl)
solution. C2000 submerged in 3.5 wt pct NaCl at room temperature is not susceptible to localized corrosion, such as pitting,
during fatigue. At an accelerated potential of 350 mV, the current responses show an increase in the current due to slip steps
emerging to the surface as a result of fatigue. The crack-initiation site and the examination of the fracture morphology are
discussed.
This article is based on a presentation given in the symposium entitled “Deformation and Fracture from Nano to Macro: A Symposium
Honoring W.W. Gerberich’s 70th Birthday,” which occurred during the TMS Annual Meeting, March 12–16, 2006 in San Antonio,
Texas and was sponsored by the Mechanical Behavior of Materials and Nanomechanical Behavior Committees of TMS.
相似文献
R.V. Steward (Graduate Student, Materials Scientist/Engineer)Email: Email: |
89.
Summary
Radical polymerization of the methacryloyl isocyanate containing 1-adamantanol (Ad-MAI) with AIBN in different solvents at
60°C was investigated. It is observed that polymerization is slower in polar solvents than in nonpolar ones. The rate of polymerization
for Ad-MAI was found to be slower than those of Adph-MAI and MMA both in photopolymerization and in thermal polymerization.
Copolymerization of Ad-MAI (M1) with styrene (M2) in benzene was studied at 60°C. The monomer reactivity ratio was calculated to be r1=1.53 and r2=0.76 according to the method of Fineman-Ross. The prominent glass transition temperature for poly(Ad-MAI) was observed at
142°C from global TSC spectrum.
Received: 20 November 1998/Revised version: 16 February 1999/Accepted: 25 February 1999 相似文献
90.
Y. X. Liu E. T. E. Kang K. G. Neoh K. L. Tan C. C. Huan D. J. Liaw 《The Journal of Adhesion》1999,17(1):35-54
Surface thermal graft copolymerization with concurrent lamination was carried out between an Ar plasma pretreated poly(vinyh'dene fluoride) (PVDF) film and a copper foil in the presence of a small quantity of a N-containing monomer, such as 4-vinyl pyridine (4-VPN) and acryloyl morpholine (ACMO), under atmospheric conditions and in the complete absence of an added polymerization initiator and system degassing. The adhesion strength, as reported by T-peel strength, was dependent on the argon plasma pretreatment time of the PVDF film, the thermal lamination temperature and the type of monomer. An optimum T-peel adhesion of about 10 N/cm was readily achieved in the Cu/PVDF laminate for grafting and lamination carried out in the presence of 4-VPN. A lower adhesion strength was obtained using ACMO and other N-containing monomers. The chemical compositions of the graft copolymerized and delaminated sample surfaces were studied by X-ray photoelectron spectroscopy (XPS). The failure mode of the Cu/4-VPN/PVDF assembly was a combined adhesional and cohesive failure. The strong adhesion between the Cu foil and the PVDF film arises from the strong charge transfer interaction between Cu and the pyridine ring, as well as the fact that the graft chains are covalently tethered on the PVDF films surfaces as a result of surface graft copolymerization. 相似文献