Alloying Elements Transition Into the Weld Metal When Using an Inventor Power Source

The temperature distribution over the surface of the welded 12Kh18N10T steel plates using the inventor power source ARC-200 has been calculated. In order to imitate multipass welding when conducting the thermal analysis the initial temperature was changed from 298K up to 798K in 100K increments. It has been determined that alloying elements transition into the weld metal depends on temperature. Using an inventor power source facilitates a uniform distribution of alloying elements along the length and height of the weld seam

Refractory TaTiNb, TaTiNbZr, and TaTiNbZrX (X = Mo, W) high entropy alloys by combined use of high energy ball milling and spark plasma sintering: Structural characterization, mechanical properties, electrical resistivity, and thermal conductivity

Refractory TaTiNb, TaTiNbZr, and TaTiNbZrX (X = Mo, W) high entropy alloys were synthesized by combined use of high energy ball milling (HEBM) and spark plasma sintering (SPS). Powders of predominantly bcc TaTiNbZrX (X = Mo, W) refractory high entropy alloys (RHEAs) were successfully prepared by short-term HEBM (60 min) and then SPS-consolidated at 1373 K for 10 mi

Assessment of fatigue damage to aircraft glass using digital holography methods

The purpose of this work is to test the digital holography method for determining the depth of fatigue surface defects of the "silver" type of aviation organic glass caused by cyclic mechanical overloads, as well as the impact of aggressive substances. To study the fatigue defects of aviation organic glass, a digital holographic camera was used, the configuration of which is an axial scheme for recording digital Gabor holograms. During the experiment, the possibility of using the digital holography method to determine the characteristic transverse dimensions of surface defects in aircraft glazing parts and longitudinal dimensions was shown. The work carried out and the created model of the digital holographic camera show the potential possibility of creating a method for checking with a given accuracy the elements of the aircraft glazing for the presence of surface damage and assessing their impact on flight safety

Наноструктурированный градиентный материал на основе псевдосплава Cu-Cr-W, полученный методами высокоэнергетической механической обработки и искрового плазменного спекания

This study was conducted to obtain nanostructured mechanically activated composite particles from immiscible metals Cu, Cr and 5÷70 wt.% W, nanostructured bulk materials based on them and Cu / Cu—Cr—W nanostructured gradient material with different tungsten content by combined short-term (up to 150 min) high-energy ball milling (HEBM) and spark plasma sintering (SPS). Cu— Cr—W mechanically activated composites were obtained by HEBM of Cu + Cr + (5÷70 wt.%)W powder mixtures in the Activator-2S ball planetary mill at the rotating speed of 1388 rpm for the grinding chamber and 694 rpm for the planetary disk in an argon atmosphere for 150 min. Cu—Cr—W mechanically activated composite particles were consolidated by SPS in the temperature range of 800— 1000 °C at a pressure of 50 MPa for 10 min. The nanostructured gradient sintered material based on Cu—Cr—W pseudo alloys was pressed layer by layer in the following sequence (from pure copper to pseudo alloy with increasing tungsten content): Cu / Cu—Cr—5%W / Cu—Cr—15%W / Cu—Cr—70%W and sintered at 800 °C for 10 min. The crystal structure, microstructure, and properties of Cu— Cr—W mechanically activated composites and consolidated materials based on them were studied depending on production conditions. It was shown that the nanostructure formed in mechanically activated composites at the short-term HEBM stage (up to 150 min) was preserved for all Cu—Cr—W (5÷70 wt.% W) compounds after SPS. Based on SEM and EDX, refractory particles of W (d ~ 20÷100 nm) and Cr (d ~ 20÷50 nm) were uniformly distributed in the material volume (in the copper matrix). The hardness of Cu—Cr—W (15 wt.% W) bulk samples obtained from nanostructured powder mixtures (after 150 min HEBM) by SPS at 800 °C was approximately 6 times higher than the hardness of samples sintered from the mixture of starting components (without HEBM). For the Cu—Cr—70%W nanostructured compound (tsps = 1000 °С) the hardness value was ~3 times higher than that for microcrystalline analogues. The highest re­lative density of 0.91 was achieved for Cu—Cr—15%W and Cu—Cr—70%W samples. Electrical resistivity for nanostructured Cu—Cr—W composites were 2 times higher than for microcrystalline samples. Apparently, this is due to an increase in grain boundaries and various defects accumulated in the material at the HEBM stage. The obtained results show that combined short-term HEBM and subsequent SPS is a promising way to produce nanocrystalline Cu—Cr—W composites and gradient materials based on them.В настоящей работе сочетанием методов непродолжительной (до 150 мин) высокоэнергетической механической обработки (ВЭМО) и искрового плазменного спекания (ИПС) были получены наноструктурированные механокомпозиты из несмешивающихся между собой металлов Cu, Crи 5÷70 мас.% W, наноструктурированные консолидированные материалы на их основе и наноструктурированный градиентный материал Cu / Cu—Cr—W с различным содержанием вольфрама. Для получения механокомпозитов Cu—Cr—Wпроводилась ВЭМО порошковых смесей Cu+ Cr+ (5÷70мас.%)\W в шаровой планетарной мельнице Активатор-2S при скорости вращения барабанов 1388 об/мин и планетарного диска 694 об/мин в среде аргона в течение 150 мин. Консолидация механокомпозитов Cu—Cr—W осуществлялась методом ИПС при температурах 800—1000 °С, давлении 50 МПа в течение 10 мин. Наноструктурированный градиентный спеченный материал на основе Cu—Cr—W-псевдосплавов запрессовывался послойно в следующей последовательности (от чистой меди к псевдосплаву с увеличением массовой доли вольфрама): Cu / Cu— Cr—5%W / Cu—Cr—15%W / Cu-Cr-70%W и спекался при температуре 800 °C в течение 10 мин. Исследованы кристаллическая структура, микроструктура и свойства механокомпозитов Cu—Cr—W и консолидированных материалов на их основе в зависимости от условий получения. Показано, что наноструктура, сформированная в механокомпозитах на стадии непродолжительной ВЭМО (до 150 мин), сохранялась после ИПС для всех составов Cu—Cr—W(5÷70 мас.% W). По данным СЭМ и ЭДС тугоплавкие частицы W (d~ 20÷100 нм) и Cr (d~ 20÷50 нм) равномерно распределены в объеме материала (в медной матрице). Твердость консолидированных образцов Cu—Cr—15%W, полученных из наноструктурированных порошковых смесей (после 150 мин ВЭМО) методом ИПС при t= 800 °С в ~6 раз превышает твердость образцов, спеченных из смеси исходных компонентов (без ВЭМО). Для наноструктурированного состава Cu—Cr—70%W(tипс = 1000 °С) значение твердости было в ~3 раза выше, чем у ми­крокристаллических аналогов. Образцы Cu—Cr—15%W и Cu—Cr—70%Wобладали наибольшей относительной плотностью — до 0,91. Удельное электрическое сопротивление наноструктурированных композитов Cu—Cr—W приблизительно в 2 раза превышало этот показатель для микрокристаллических образцов. Это может быть обусловлено увеличением гра­ниц зерен и накоплением различного рода дефектов в материале на стадии ВЭМО. Полученные результаты показывают перспективность использования сочетания методов кратковременной ВЭМО и последующего ИПС для создания консолидированных нанокристаллических композитов Cu—Cr—Wи градиентных материалов на их основе

Systematic study of flow vector fluctuations in √SNN=5.02 TeV Pb-Pb collisions

Measurements of the pT-dependent flow vector fluctuations in Pb-Pb collisions at sNN=5.02TeV using azimuthal correlations with the ALICE experiment at the Large Hadron Collider are presented. A four-particle correlation approach [ALICE Collaboration, Phys. Rev. C 107, L051901 (2023)2469-998510.1103/PhysRevC.107.L051901] is used to quantify the effects of flow angle and magnitude fluctuations separately. This paper extends previous studies to additional centrality intervals and provides measurements of the pT-dependent flow vector fluctuations at sNN=5.02TeV with two-particle correlations. Significant pT-dependent fluctuations of the V - 2 flow vector in Pb-Pb collisions are found across different centrality ranges, with the largest fluctuations of up to ∼15% being present in the 5% most central collisions. In parallel, no evidence of significant pT-dependent fluctuations of V - 3 or V - 4 is found. Additionally, evidence of flow angle and magnitude fluctuations is observed with more than 5σ significance in central collisions. These observations in Pb-Pb collisions indicate where the classical picture of hydrodynamic modeling with a common symmetry plane breaks down. This has implications for hard probes at high pT, which might be biased by pT-dependent flow angle fluctuations of at least 23% in central collisions. Given the presented results, existing theoretical models should be reexamined to improve our understanding of initial conditions, quark-gluon plasma properties, and the dynamic evolution of the created system

Skewness and kurtosis of mean transverse momentum fluctuations at the LHC energies

The first measurements of skewness and kurtosis of mean transverse momentum (〈pT〉) fluctuations are reported in Pb–Pb collisions at sNN = 5.02 TeV, Xe–Xe collisions at sNN = 5.44 TeV and pp collisions at s=5.02 TeV using the ALICE detector. The measurements are carried out as a function of system size 〈dNch/dη〉|η|<0.51/3, using charged particles with transverse momentum (pT) and pseudorapidity (η), in the range 0.2<3.0 GeV/c and |η|<0.8, respectively. In Pb–Pb and Xe–Xe collisions, positive skewness is observed in the fluctuations of 〈pT〉 for all centralities, which is significantly larger than what would be expected in the scenario of independent particle emission. This positive skewness is considered a crucial consequence of the hydrodynamic evolution of the hot and dense nuclear matter created in heavy-ion collisions. Furthermore, similar observations of positive skewness for minimum bias pp collisions are also reported here. Kurtosis of 〈pT〉 fluctuations is found to be in good agreement with the kurtosis of Gaussian distribution, for most central Pb–Pb collisions. Hydrodynamic model calculations with MUSIC using Monte Carlo Glauber initial conditions are able to explain the measurements of both skewness and kurtosis qualitatively from semicentral to central collisions in Pb–Pb system. Color reconnection mechanism in PYTHIA8 model seems to play a pivotal role in capturing the qualitative behavior of the same measurements in pp collisions

Multiplicity and event-scale dependent flow and jet fragmentation in pp collisions at √s=13 TeV and in p-Pb collisions at √sNN=5.02 TeV

Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at s = 13 TeV and p–Pb collisions at sNN = 5.02 TeV. The correlation functions are measured as a function of relative azimuthal angle ∆φ and pseudorapidity separation ∆η for pairs of primary charged particles within the pseudorapidity interval |η| < 0.9 and the transverse-momentum interval 1 < pT< 4 GeV/c. Flow coefficients are extracted for the long-range correlations (1.6 < |∆η| < 1.8) in various high-multiplicity event classes using the low-multiplicity template fit method. The method is used to subtract the enhanced yield of away-side jet fragments in high-multiplicity events. These results show decreasing flow signals toward lower multiplicity events. Furthermore, the flow coefficients for events with hard probes, such as jets or leading particles, do not exhibit any significant changes compared to those obtained from high-multiplicity events without any specific event selection criteria. The results are compared with hydrodynamic-model calculations, and it is found that a better understanding of the initial conditions is necessary to describe the results, particularly for low-multiplicity events

Emergence of Long-Range Angular Correlations in Low-Multiplicity Proton-Proton Collisions

This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s=13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4<|Δη|<1.8 and a transverse momentum of 1<2 GeV/c, as a function of the charged-particle multiplicity measured at midrapidity. This Letter extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly interacting medium is unlikely to be formed. The precision of the new low multiplicity results allows for the first direct quantitative comparison with the results obtained in e+e- collisions at s=91 GeV and s=183-209 GeV, where initial-state effects such as preequilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range

Charged-particle production as a function of the relative transverse activity classifier in pp, p-Pb, and Pb-Pb collisions at the LHC

Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum pTtrig in the range 8 < 15 GeV/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier, RT=NchT/NchT, is used to group events according to their UE activity, where NchT is the charged-particle multiplicity per event in the transverse region and NchT is the mean value over the whole analysed sample. The energy dependence of the RT distributions in pp collisions at s = 2.76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particle pT spectra as a function of RT in the three azimuthal regions in pp, p–Pb, and Pb–Pb collisions at sNN = 5.02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p–Pb)

Prompt and non-prompt J/ψ production at midrapidity in Pb-Pb collisions at √sNN=5.02 TeV

The transverse momentum (pT) and centrality dependence of the nuclear modification factor RAA of prompt and non-prompt J/ψ, the latter originating from the weak decays of beauty hadrons, have been measured by the ALICE collaboration in Pb–Pb collisions at sNN = 5.02 TeV. The measurements are carried out through the e+e− decay channel at midrapidity (|y| < 0.9) in the transverse momentum region 1.5 < pT < 10 GeV/c. Both prompt and non-prompt J/ψ measurements indicate a significant suppression for pT > 5 GeV/c, which becomes stronger with increasing collision centrality. The results are consistent with similar LHC measurements in the overlapping pT intervals, and cover the kinematic region down to pT = 1.5 GeV/c at midrapidity, not accessible by other LHC experiments. The suppression of prompt J/ψ in central and semicentral collisions exhibits a decreasing trend towards lower transverse momentum, described within uncertainties by models implementing J/ψ production from recombination of c and c ̄ quarks produced independently in different partonic scatterings. At high transverse momentum, transport models including quarkonium dissociation are able to describe the suppression for prompt J/ψ. For non-prompt J/ψ, the suppression predicted by models including both collisional and radiative processes for the computation of the beauty-quark energy loss inside the quark-gluon plasma is consistent with measurements within uncertainties