scholarly journals Discussion on the Peak Shift of Α-Ti Phase in Tio2 Nanostructured Coatings on Ti-6Al-4V Alloy

2018 ◽  
Author(s):  
Linh Nguyen ◽  
Zhong-Tao Jiang ◽  
Jaegyu Kim ◽  
Seungbum Hong ◽  
Kwangsoo No
Keyword(s):  
Annealing Temperature ◽  
Rf Sputtering ◽  
Peak Shift ◽  
Nanostructured Coatings ◽  
Ti Alloy ◽  
Thermal Expansion Coefficients ◽  
H2o2 Oxidation ◽  
Expansion Coefficients ◽  
The Difference ◽  
Hcp Structure

In this study, TiO2 nanostructured coatings on Ti-6A-4V alloys were fabricated by two methods: H2O2 oxidation and RF sputtering. In the annealing temperature range of 25 C - 500 C, there were the peaks at 35, 37, 40 and 52 corresponding to {100}, {002}, {101} and {102} crystal planes of hcp structure of α-Ti. At the annealing temperature of 600 C, there was the presence of peaks corresponding to crystal planes of anatase and rutile TiO2. The relative intensities of anatase and rutile phases of the sample fabricated by RF sputtering were 3.62 and 10.25 %, respectively; while those of the sample fabricated by H2O2 oxidation were 21.27 and 3.20 %, respectively (The relative intensity of α-Ti phase was 100 %). The results investigated the peak shift of α-Ti phase in TiO2/Ti-6Al-4V nanostructured coatings fabricated by the two methods which was reasonably explained from the difference in the thermal expansion coefficients of Ti alloy and TiO2 components, as well as the difference in the ratio of anatase to rutile phases.

Effect of SiO2 Cap Layer on Thermal Stability of Nickel and Nickel-Cobalt Silicide

2006 ◽  
Vol 321-323 ◽  
pp. 1322-1325
Author(s):  
Kil Jin Han ◽  
Yu Jeong Cho ◽  
Soon Young Oh ◽  
Yong Jin Kim ◽  
Won Jae Lee ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Annealing Temperature ◽  
Nickel Silicide ◽  
Cobalt Silicide ◽  
Thermal Expansion Coefficients ◽  
Nickel Cobalt ◽  
Expansion Coefficients ◽  
The Difference ◽  
The Stability ◽  
Thermal Stability Of

We investigated the effect of SiOcap layer on the thermal stability of nickel and nickel-cobalt silicide by measuring its sheet resistance. The stability of nickel silicide was deteriorated as a function of annealing temperature, while that of nickel-cobalt silicide was not. In case of both silicides, the SiOcap layer improved the stability. Tensile stress from the difference of thermal expansion coefficients between SiO2 and nickel silicide may suppress the agglomeration of nickel silicide.

Influence of Magnetoelastic Anisotropy on Properties of Nanostructured Microwires

2013 ◽  
Vol 646 ◽  
pp. 59-66 ◽  
Author(s):  
Arcady Zhukov ◽  
Margarita Churyukanova ◽  
Lorena Gonzalez-Legarreta ◽  
Ahmed Talaat ◽  
Valentina Zhukova ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Hysteresis Loops ◽  
Magnetic Behaviour ◽  
Soft Magnetic ◽  
Magnetoelastic Anisotropy ◽  
Thermal Expansion Coefficients ◽  
Magnetoelastic Energy ◽  
Expansion Coefficients ◽  
The Difference ◽  
Magneto Resistance

We studied the effect ofthe magnetoelastic ansitropy on properties of nanostructured glass-coated microwires with soft magnetic behaviour (Finemet-type microwires of Fe70.8Cu1Nb3.1Si14.5B10.6, Fe71.8Cu1Nb3.1Si15B9.1 and Fe73.8Cu1Nb3.1Si13B9.1 compositions) and with granular structure (Cu based Co-Cu microwires). The magnetoelastic energy originated from the difference in thermal expansion coefficients of the glass and metallic alloy during the microwires fabrication, affected the hysteresis loops, coercivity and heat capacity of Finemet-type microwires. Hysteresis loops of all as-prepared microwires showed rectangular shape, typical for Fe-rich microwires. As expected, coercivity, HC, of as-prepared microwires increases with decreasing of the ratio ρ defined as the ratio between the metallic nucleus diameter, d to total microwire diameter, D. On the other hand we observed change of heat capacity in microwires with different ratio ρ. In the case of Co-Cu microwires ρ- ratio affected the structure and the giant magneto-resistance of obtained microwires.

scholarly journals Состояние топологического изолятора в тонких пленках висмута под воздействием плоскостной деформации растяжения

2018 ◽  
Vol 60 (3) ◽  
pp. 452
Author(s):  
Е.В. Демидов ◽  
В.М. Грабов ◽  
В.А. Комаров ◽  
Н.С. Каблукова ◽  
А.Н. Крушельницкий
Keyword(s):  
Carrier Density ◽  
Considerable Increase ◽  
Surface States ◽  
Substrate Material ◽  
Experimental Examination ◽  
Thermal Expansion Coefficients ◽  
Galvanomagnetic Properties ◽  
Bismuth Films ◽  
Expansion Coefficients ◽  
The Difference

AbstractThe results of experimental examination of galvanomagnetic properties of thin bismuth films subjected to plane tensile strain resulting from the difference in thermal expansion coefficients of the substrate material and bismuth are presented. The resistivity, the magnetoresistance, and the Hall coefficient were studied at temperatures ranging from 5 to 300 K in magnetic fields as strong as 0.65 T. Carrier densities were calculated. A considerable increase in carrier density in films thinner than 30 nm was observed. This suggests that surface states are more prominent in thin bismuth films on mica substrates, while the films themselves may exhibit the properties of a topological insulator.

scholarly journals Fabrication and Characterization of the Newly Developed Superalloys Based on Inconel 740

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2362 ◽  
Author(s):  
Małgorzata Grudzień-Rakoczy ◽  
Łukasz Rakoczy ◽  
Rafał Cygan ◽  
František Kromka ◽  
Zenon Pirowski ◽  
...  
Keyword(s):  
Solidus Temperature ◽  
Chemical Compositions ◽  
Scanning Calorimetry ◽  
Dendritic Microstructure ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Fabrication And Characterization ◽  
The Difference

The chemical composition of standard Inconel 740 superalloy was modified by changes in the Al/Ti ratio (0.7, 1.5, 3.4) and addition of Ta (2.0, 3.0, 4.0%). Remelted Inconel 740 (A0) and nine variants with various chemical compositions were fabricated by lost-wax casting. The microstructure, microsegregation, phase transformation temperatures, thermal expansion coefficients and hardness of the superalloys were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, dilatometry and Vickers measurements. Typical dendritic microstructure was revealed with microsegregation of the alloying elements. Segregation coefficient ki for Ti, Nb and Ta did not exceed unity, and so precipitates enriched mainly in these elements were found in interdendritic spaces. The Nb-rich blocky precipitates, MC carbides, MN nitrides, oxides, and fine γ’ was in all modified castings. Presence of other microstructural features, such as Ti-rich needles, eutectic γ-γ’ islands, small Al-rich and Cr-rich precipitates depended on the casting composition. The lowest solidus and liquidus temperatures were observed in superalloys with a high Al/Ti ratio. Consequently, in A7–A9 variants, the solidification range did not exceed 100 °C. In the A0 variant the difference between liquidus and solidus temperature was 138 °C. Hardness of all modified superalloys was at least 50% higher than for the remelted Inconel 740 (209 HV10).

Athermal Motion of Grain Boundaries, Twins and Triple Junctions in Zn

2004 ◽  
Vol 467-470 ◽  
pp. 801-806 ◽  
Author(s):  
Vera G. Sursaeva
Keyword(s):  
Thermal Expansion ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Triple Junction ◽  
Triple Junctions ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
The Difference ◽  
The Individual ◽  
Individual Grains

When a bicrystal or polycrystal are subjected to a change in temperature, the individual responses of the two adjoining crystals may differ in a manner, which tends to produce a dilatational mismatch along grain boundaries. If compatibility is to be retained along the interface, an additional set of stresses must then be generated in order to conserve this compatibility. ‘Compatibility stresses’ will also be generated whenever a polycrystal is heated or cooled and the thermal expansion coefficients of the individual grains are different due to thermal expansion anisotropy. In such cases adjacent grains will attempt to change dimensions and develop mismatches by amounts controlled by the parameter Δa*ΔΤ, where Δa is the difference between the thermal expansion coefficients in the appropriate directions, and ΔΤ is the temperature change. These ‘compatibility stresses’ may be relieves if grain boundary motion, triple junction migration and grain growth are possible. These ‘compatibility stresses’ may play important role in the kinetic behavior of the microstructure ranging from influencing the behavior of lattice dislocations near the grain boundaries to promoting grain boundary and triple junction dragging or moving. The motion of the ‘special’ grain boundaries, triple junctions with ‘special’ grain boundaries and twins under the influence of internal mechanical stresses is the main subject of this paper.

Dispersion Strengthening of Metallic Glasses

1983 ◽  
Vol 28 ◽  
Author(s):  
P.E. Donovan
Keyword(s):  
Mechanical Properties ◽  
Metallic Glasses ◽  
Fracture Stress ◽  
Stress Fields ◽  
Tensile Fracture ◽  
Dispersion Strengthening ◽  
Thermal Expansion Coefficients ◽  
Compressive Stresses ◽  
Expansion Coefficients ◽  
The Difference

ABSTRACTIt is proposed that the effects of crystalline inclusions on the mechanical properties of metallic glasses are due to the presence of compressive stress-fields arising from the difference in thermal expansion coefficients of the crystals and the glass. Because of the dilatational micro-mechanism of plastic flow in metallic glasses these compressive stresses raise the tensile fracture stress but reduce the hardness. The temperature dependence of the hardness changes in partially crystallised Fe40Ni40P14B6 is consistent with this model.

Study of the Ti-Mn-Al-Si-O-S Complex Inclusions Inducing Intragranular Acicular Ferrite

2012 ◽  
Vol 535-537 ◽  
pp. 620-627 ◽  
Author(s):  
Chengwei Yang ◽  
Min Jiang ◽  
Xinhua Wang ◽  
Tie Ou
Keyword(s):  
Thermal Expansion ◽  
Confocal Laser ◽  
Complex Inclusion ◽  
Inclusion Formation ◽  
The Core ◽  
Thermal Expansion Coefficients ◽  
Intragranular Acicular Ferrite ◽  
Expansion Coefficients ◽  
The Difference ◽  
Confocal Laser Microscope

High temperature confocal laser microscope, FE-SEM-EDS and EPMA were utilized to study the Ti-Mn-Al-Si-O-S complex inclusion inducing IAF in Ti deoxidized steel. FactStage was also used to calculate the thermodynamics of inclusion formation. It was demonstrated that when the cooling rate is fixed to 5°C/s, IAF can be induced by complex inclusions which act as the core of IAF at 609°C. Microstructure of the complex inclusions is complicated. These inclusions are consisted of the TiOx-MnO core which is surrounded by MnO-Al2O3-SiO2 complex inclusions and small amount of MnS. The reason that Ti-Mn-Al-Si-O-S complex inclusions can induce IAF is that a Mn-depleted zone is formed by the core TiOx-MnO and the MnS around it. Meanwhile, the difference between MnO-Al2O3-SiO2 and austenite thermal expansion coefficients is tremendous is another principle element for the IAF formation.

Thermodynamics of Epitaxial Ferroelectric Films.

1995 ◽  
Vol 401 ◽  
Author(s):  
S. B. Desu ◽  
V. P. Dudkevich ◽  
P. V. Dudkevich ◽  
I. N. Zakharchenko ◽  
G. L. Kushlyan
Keyword(s):  
Thermal Expansion ◽  
Phase Transitions ◽  
Misfit Dislocations ◽  
Ferroelectric Films ◽  
Growth Stresses ◽  
Substrate Interaction ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
The Difference ◽  
Film Substrate

AbstractThe problem of phase transitions and physical properties of the BaTiO3-type films on the (001) single-crystal substrates of the cubic syngony was solved in the limits of the Landau- Devonshire thermodynamics. The thermoelastic film-substrate interaction caused by the difference between thermal expansion coefficients was strictly taken into consideration. The model was based on the following assumptions: 1) the film is closely conjugated with the substrate; 2) the film is sufficiently “thick”to find itself unstrained at the growth temperature Ts, ( growth stresses were compensated by misfit dislocations ), and 3) the film is sufficiently “thin, and the stresses arising at the temperatures T>Ts may be considered to be uniform.

Interdiffusion Mechanisms in GaAs/AlGaAs Quantum Well Heterostructures Induced by SiO2 Capping and Annealing

1997 ◽  
Vol 484 ◽  
Author(s):  
A. Pépin ◽  
C. Vieu ◽  
M. Schneider ◽  
H. Launois ◽  
E. V. K. Rao
Keyword(s):  
Quantum Well ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Semiconductor Surface ◽  
Simultaneous Generation ◽  
Spatial Control ◽  
Thermal Chemical Vapor Deposition ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
The Difference

AbstractWe have investigated intermixing enhancement in GaAs/AlGaAs quantum well heterostructures achieved by SiO2 capping obtained by rapid thermal chemical vapor deposition. Evidence of fast Ga pumping inside the SiO2 layer during anneal and simultaneous generation of excess Ga vacancies under the SiO2/GaAs interface is presented. A simple model involving the thermal stress arising from the difference in thermal expansion coefficients between SiO2 and GaAs, is proposed to account for the abnormally fast Ga vacancy diffusion inside the heterostructure. A spatial control of the interdiffused areas can be achieved if a suitable stress field is imposed on the semiconductor surface by the capping layers. We show experimental evidence of this effect using a specific patterning of SiO2/Si3N4 bilayers.

Strained Linbo3/Sapphire Heterostructures Grown by Pulsed Laser Deposition

1995 ◽  
Vol 397 ◽  
Author(s):  
Yoshihiko Shibata ◽  
Naohiro Kuze ◽  
Masahiro Matsui ◽  
Masaki Kanai ◽  
Tomoji Kawai
Keyword(s):  
Diffraction Analysis ◽  
Pulsed Laser ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Thermal Expansion Coefficients ◽  
Transmission Electron ◽  
Expansion Coefficients ◽  
The Difference ◽  
Deposited Films

ABSTRACTThin LiNbO3 films are deposited on (001) sapphire substrates by Ar F pulsed laser ablation. The films are evaluated by X-ray diffraction analysis at various temperatures, as well as high-resolution transmission electron microscopy (TEM). The deposited films are highly epitaxial but that are strained, that is, the a-axis is longer and the c-axis is shorter than those of LiNbO3 single crystals. X-ray diffraction analysis at deposition temperature, as well as TEM show that the strain is caused by the difference in thermal expansion coefficients between LiNbO3 and sapphire substrates.

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