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1.
N. Bibić I. H. Wilson M. Milosavljević D. Perusko 《Journal of Materials Science》1992,27(18):4945-4948
Elemental sputtering yields from two phase AgCu alloys were measured for 20, 40 and 50 at% Ag. Argon ion bombardment energies were in the range 35–55 keV and the ion dose was 1×1019 ions cm–2. The sputtering yield for silver was found to be considerably below what was expected by simple selective sputtering of a two component alloy. Analysis by electron probe X-ray microanalysis and scanning electron microscopy of the eroded surface indicated that surface diffusion of copper from copper rich grains and geometrical constraints in the dense cone forest on Cu/Ag eutectic regions combine to reduce the sputtering yield for silver. 相似文献
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《Materials Science & Technology》2013,29(2):105-109
AbstractThe main models (mixture laws, finite element methods, self-consistent methods) proposed to describe the stress–strain curve of a two-phase material from the stress–strain curves of its components have been considered. None of these models exactly describes the behaviour of the two-phase alloys (each phase equal vol.-%) studied (Cu–Ag and Cd–Zn).MST/473 相似文献
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Al/Al2O3 alloys are characterised by a pronounced high-temperature brittleness which is not yet fully understood. The authors postulated that microcrack formation plays a fundamental role in determining the ductility in tensile and creep tests of these alloys. To investigate the appearance and generation of cracks, density measurements and electron microscope examinations were carried out on samples broken in tensile tests (20 to 620° C temperature range) and in accelerated creep tests (450° C) of two Al/Al2O3 alloys (SAP-ISML and Fibroxal). Some investigations were also made on samples deformed by swaging.The experimental results (morphology, dimensions, distribution and volume of microcracks in the broken samples as a function of temperature and deformation time) confirmed the crack-formation hypothesis and showed that during the deformation of sintered aluminium two-phase alloys, voids may be generated by two mechanisms. The first involves the opening of pre-existing pores which are due to imperfect bonding between matrix and particles, the second involves the creation of new cracks by dislocations blocked at second phase particles. 相似文献
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V. A. Podoroga 《Strength of Materials》1990,22(9):1345-1351
Regularities in the formation of residual thermal stresses in two-phase alloys in relation to structure and the physicomechanical properties of phases are studied. Results are given for the calculation of intergranular reaction forces in the vicinity of pores filled with binder occurring as a result of the difference in thermal expansion coefficients for the phases. The dependence of the magnitude of intergranular reaction on the percentage content of binder is analyzed.Translated from Problemy Prochnosti, No. 9, pp. 81–86, September, 1990. 相似文献
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《Materials Science & Technology》2013,29(3):217-223
AbstractStress intensity levels at the tip of cracks approaching and growing past second-phase particles have been computed using finite element methods. It is predicted that particles having a lower modulus than the matrix (i.e. ‘soft’ particles) attract and accelerate cracks growing into their vicinity, whereas ‘hard’ particles deflect them and retard local growth. A reverse, but weaker, effect is indicated once the crack has extended past a particle. Using a ferrite matrix with either spheroidized cementite or spheroidal graphite as the second phase, these predictions have been largely verified experimentally. An apparent anomaly is the cross-over in the growth rate curves of the cast iron and the totally ferritic microstructure. However, this may be explained by the requirement for the crack to reinitiate following its interaction with each graphite particle, during which decohesion of the particle/matrix interface occurs.MST/417 相似文献
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Grain and phase growth in the two-phase Al-Cu alloys containing 6, 11, 1 7, 24 and 33 wt % Cu were investigated by annealing at 535 °C for 0.5–100 h. The grain and phase sizes of the phase are seen to be larger than that of the phase. The size of phase decreases whereas the size of phase increases with increasing copper content in the alloy. As such, the phase- and grain-size distributions are broader than the phase- and grain-size distributions, but the size range depends on annealing time and alloy composition. The grain sizes of the ,d
, and ,d
, phases can be related to the volume fraction of the phase,f
, according to the equationd
= 0.497d
/f
. 相似文献
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An electrolytic method for preparing chemically resistant Pm-Ni alloys was developed. Optimal electrolysis conditions ensuring
maximal Pm recovery from the electrolyte (up to 95%) with the alloy formation were determined. Side steps of the process were
examined. The main of them is reduction of Pm in the bulk of the electrolyte with alkali metal subions. 相似文献
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Microduplex 60/40 brass and Zn-AI eutectoid were used as models to represent cavitating and non-cavitating classes of the two superplastic alloys, respectively. In addition, a series of alloys were produced to represent the individual phases, over a wide range of temperatures, in these model systems. Hardness, Young's modulus and tensile tests were carried out on all these alloys at temperatures between 20 and 700° C. Analysing the above data, a criterion for the occurrence of cavitation in two-phase superplastic alloys is proposed.[/p] 相似文献
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M. A. Shtremel' 《Strength of Materials》1972,4(9):1103-1106
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Nian Xian Zhang Megumi Kawasaki Yi Huang Terence G. Langdon 《Journal of Materials Science》2013,48(13):4582-4591
The Zn-22 % Al eutectoid alloy and the Pb-62 % Sn eutectic alloy were processed by high-pressure torsion (HPT) over a range of experimental conditions. Both alloys exhibit similar characteristics with significant grain refinement after processing by HPT but with a reduction in the hardness values by comparison with the initial unprocessed conditions. It is shown that there are generally smaller grains at the edges of the disks by comparison with the disk centers. The hardness results in these two alloys are mutually consistent, but they are different from those generally reported for conventional single-phase materials. The significance of this difference is examined. 相似文献
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Jiancheng Tang Baiyun HuangYuehui He Wensheng LiuKechao Zhou Aihua Wu 《Materials Research Bulletin》2002,37(7):1315-1321
The dependences of the room temperature tensile properties of two-phase TiAl alloys with fully lamellar microstructures on colony size and the effects of alloying elements on the k value of Hall-Petch relationship were investigated. It is found that the ultimate tensile strength and the yield strength show Hall-Petch dependences on colony size, but the ductility does not obey a Hall-Petch dependence on colony size. The k value of Hall-Petch relationship increases when Ti-47Al (at.%) is alloyed with interstitial elements C or B, but the additions of substitutional elements Cr or Nb don’t lead to its apparent change. 相似文献
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Al-Cu alloys containing 6, 11, 17, 24 and 33 wt% Cu, annealed for 0.5–100 h, were deformed by the differential strain-rate test technique over a strain-rate range of 4×10–6 to 3×10–2s–1 at temperatures ranging from 460–540°C. Superplastic behaviour, with strain-rate sensitivity, m0.5, and activation energy, Q=171.5 kJ mol–1, is shown by the Al-24Cu and Al-33Cu alloys at lower strain rates and higher temperatures. All the alloys show m0.20 at higher strain rates, but the average activation energy for deformation of the Al-6Cu, Al-11Cu, and Al-17Cu alloys is evaluated to be 480.7 kJ mol–1, in contrast to a lower value of 211 kJ mol–1 for the Al-24Cu and Al-33Cu alloys. Instead of grain size, the mean free path between particles is suggested to be a more appropriate microstructural parameter for the constitutive relationship for deformation of the Al-Cu alloys. 相似文献
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Two-phase (B2+L12) nickel aluminide intermetallic compounds were synthesized by the pressure-assisted volume combustion synthesis (CS). The production and characterization of the samples containing NiAl+Ni3Al were investigated. Aluminum (99% pure, 15 μm) and carbonyl nickel (99.8 pure, 4-7 μm) powders were used. The production of intermetallic compound was carried out at 1050 °C under 150 MPa uniaxial pressure in open air atmosphere in an electrical resistance furnace for 60 min. The formation temperature of intermetallic compound was determined by differential scanning calorimeter (DSC) analysis, and exothermic temperature of powder mixture was determined as 653 °C. The characterization of samples was confirmed by optical microscope, SEM and XRD analysis. It was observed that the structure of compound has very low porosity and the formation of NiAl was completed successfully. The relative density of test materials measured according to Archimedes’ principle was 98.04%. The microhardness of test materials was about 351 HVN1. 相似文献
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In an attempt to resolve the difficulties in interpreting the behaviour of the industrial maraging steel of VASCOMAX 300 type, we have studied the influence of separate or simultaneous additions of Co and Mo on the structural transformations taking place during the heating cycles at moderate rates (300° Ch–1) for the Fe-Ni base alloys. An interpretation of the mechanisms of the M transformation, implying preponderantly diffusional mechanisms, has been proposed for the alloys Fe-Ni, Fe-Ni-Co, Fe-Ni-Mo and Fe-Ni-Co-Mo for which the Ni/Fe, Mo/Fe ratios are equal to those of the reference maraging steel. The ageing phenomena in the martensite of the alloys containing Mo have been studied and show the formation of G.P. zones having a diameter of a few tens of Å and spaced at an average distance of 120 Å, in the case of the quaternary alloy, at temperatures of 400 to 450° C. 相似文献
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The effect of microstructure on the mechanical properties of two-phase titanium alloys 总被引:1,自引:0,他引:1
This article presents the results of investigations of microstructure and mechanical properties of two-phase +β titanium alloys with different volume fraction of the β-phase. Microstructure of the specimens was examined using an optical microscope. Fracture surfaces were observed by SEM technique. The influence of the microstructure and phase composition on the mechanical properties of the alloys was studied. Static tensile tests, hardness tests and fatigue investigations were performed. It was noticed that the volume fraction and chemical composition of the β-phase has a significant effect on mechanical properties and cracking process during fatigue. 相似文献
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Tadahiko Furuta Shigeru Kuramoto Kayo Horibuchi Tetsu Ohsuna Zenji Horita 《Journal of Materials Science》2010,45(17):4745-4753
Microstructural evolution of an Fe–18.1%Ni–34.9%Co–9.3%Ti (in at.%) in processing by high-pressure torsion (HPT) was investigated by electron backscatter diffraction. After 10 turns of HPT straining at room temperature with a rotation speed of 1 rpm under a pressure of 6 GPa, the alloy was composed of body-centered cubic-structured grains with sizes of 20–50 nm having high density crystal defects inside the grains. The mechanism of this significant grain refinement was discussed in relation to the stress-induced martensitic transformation and transgranular shear near ideal strength. The actual shear stress of the nanocrystalline iron-based alloy was estimated to be 1.37 GPa and as high as 38% of the ideal shear stress, which is similar to Gum Metal exhibiting deformation without dislocation activity. It is inferred from these results that the dislocation motion can be suppressed up to ultrahigh stress level near ideal strength by the formation of nano-sized grains. 相似文献