Formation Mechanism of Micro- and Nanocrystalline Surface Layers in Titanium and Aluminum Alloys in Electron Beam Irradiation

Невский, С. А.; Sarychev, V. D.; Konovalov, S. V.; Granovskii, Alexey; Громов, В. Е.

doi:10.3390/met10101399

Cited by 17 publications

(17 citation statements)

References 27 publications

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“…Currently, the modification of the surface properties of the materials can be achieved by a number of methods, such as thin film deposition [9], ion implantation [10], treatment and alloying of the surface by high energy fluxes, such as electron beam [11][12][13], laser beam [14,15]. The electron-beam surface alloying receives a lot of attention due to the possibility of precise control of the technological conditions, short process time, uniform distribution of the energy of the electron beam, and so on [16].…”

Section: Introductionmentioning

confidence: 99%

Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Valkov

Дечев

Ivanov

et al. 2021

Metals

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In this study, we present the results of Young’s modulus and coefficient of friction (COF) of Ti–Ta surface alloys formed by electron-beam surface alloying by a scanning electron beam. Ta films were deposited on the top of Ti substrates, and the specimens were then electron-beam surface alloyed, where the beam power was varied from 750 to 1750 W. The structure of the samples was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Young’s modulus was studied by a nanoindentation test. The coefficient of friction was studied by a micromechanical wear experiment. It was found that at 750 W, the Ta film remained undissolved on the top of the Ti, and no alloyed zone was observed. By an increase in the beam power to 1250 and 1750 W, a distinguished alloyed zone is formed, where it is much thicker in the case of 1750 W. The structure of the obtained surface alloys is in the form of double-phase α’and β. In both surface alloys formed by a beam power of 1250 and 1750 W, respectively, Young’s modulus decreases about two times due to different reasons: in the case of alloying by 1250 W, the observed drop is attributed to the larger amount of the β phase, while at 1750 W is it due to the weaker binding forces between the atoms. The results obtained for the COF show that the formation of the Ti–Ta surface alloy on the top of Ti substrate leads to a decrease in the coefficient of friction, where the effect is more pronounced in the case of the formation of Ti–Ta surface alloys by a beam power of 1250 W.

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Section: Introductionmentioning

confidence: 99%

Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Valkov

Дечев

Ivanov

et al. 2021

Metals

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“…The present dendrite growth algorithm does not consider the remelting effect, the breaking process of dendrite fragments, and the influence of the melt convection on the quantity and position of crystal nuclei because these required duplicated model construction and huge computational efficiency. Future research can learn from the methods in computational fluid dynamics [45,46] to optimize and expand the model. The contribution of dendrite fragmentation due to the vibration-induced convection was incorporated into the nucleation model by increasing the probability of nucleation event in liquid.…”

Section: The Simulation Principle Of Techniquementioning

confidence: 99%

Numerical Simulation of Microstructure Evolution in Solidification Process of Ferritic Stainless Steel with Cellular Automaton

et al. 2021

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In order to study the basic principles of vibration-excited liquid metal nucleation technology, a coupled model to connect the temperature field calculated by ANSYS Fluent and the dendritic growth simulated by cellular automaton (CA) algorithm was proposed. A two-dimensional CA model for dendrite growth controlled by solute diffusion and local curvature effects with random zigzag capture rule was developed. The proposed model was applied to simulate the temporal evolution of solidification microstructures under different degrees of surface undercooling and vibration frequency of the crystal nucleus generator conditions. The simulation results showed that the predicted columnar dendrites regions were more developed, the ratio of interior equiaxed dendrite reduced and the size of dendrites increased with the increase of the surface undercooling degrees on the crystal nucleus generator. It was caused by a large temperature gradient formed in the melt. The columnar-to-equiaxed transition (CET) was promoted, and the refined grains and homogenized microstructure were also achieved at the high vibration frequency of the crystal nucleus generator. The influences of the different process parameters on the temperature gradient and cooling rates in the mushy zone were investigated in detail. A lower cooling intensity and a uniform temperature gradient distribution could promote nucleation and refine grains. The present research has guiding significance for the process parameter selection in the actual experimental.

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“…One of the most probable mechanisms responsible for their forming is thought to be various hydrodynamic instabilities, e. g. the Mullins-Sekerka instability [6], thermocapillary instability [7,8] and the Kelvin-Helmholtz instability [9,10]. An assumption was made [11,12] that micro-and nanostructure phase states develop in multicomponent alloys owing to the evolving combination of thermal, concentration-evaporation and thermoelectric instabilities. This study investigates the effect of an electron beam with the energy density from 10 to 30 J / cm 2 from 225.83 to 618.87 nm was formed on the treated surface.…”

Section: Introductionmentioning

confidence: 99%

The mechanism of formation of surface micro- and nanostructures in the AlCoCrFeNi high-entropy alloy during electron-beam treatment

et al. 2021

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The paper is devoted to a study of the formation of submicron and nanosized cellular crystallization structures on the surface of a high-entropy AlCoCrFeNi alloy irradiated by high current electron beams with the energy density varying from 10 to 30 J / cm 2 and a pulse time of 200 μs. The study revealed that the combination of thermal, evaporation-capillary and thermoelectric instabilities induces the formation of submicro-and nanodimensional cellular structures similarly to high-entropy alloys. The proposed dispersion equation was analyzed to detect the conditions for the generation of this instability. The importance of the evaporation process was investigated by finding a solution to the heat problem with phase transformations. The temperature distribution over time calculated at different distances from the surface of the alloy samples demonstrated that the surface temperature is lower than the evaporation temperature for the energy density E s < 30 J / cm 2 , therefore, the term of evaporation in the dispersion equation was ignored for these values of the energy density. The analysis of the dispersion equation showed that for E s = 30 J / cm 2 , the wavelength λ m with the maximal growth rate of perturbations on the melt surface gains a value in the submicro-and nano-range, provided that the thermoelectric coefficient equals to ~4 -10 V / K, and the pressure of evaporation is ~10 5 Pa. If we exclude thermoelectric effects, these values λ m are observed for the pressure of evaporation ~10 11 Pa. The wavelength λ m was revealed to decrease according to a power law as the beam energy density increases.

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Formation Mechanism of Micro- and Nanocrystalline Surface Layers in Titanium and Aluminum Alloys in Electron Beam Irradiation

Cited by 17 publications

References 27 publications

Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Numerical Simulation of Microstructure Evolution in Solidification Process of Ferritic Stainless Steel with Cellular Automaton

The mechanism of formation of surface micro- and nanostructures in the AlCoCrFeNi high-entropy alloy during electron-beam treatment

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