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Chandan Choudhary,H. N. Bar,A. K. Pramanick,K. L. Sahoo,Durbadal Mandal 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.10
In this study, simultaneous effects of modified strain induced melt activation (M-SIMA) process and addition of Al-5Ti-1Bchemical grain refiner on the casting defects, microstructural features, and mechanical properties of hypoeutectic Al-7Sialloys are investigated. The traditional melting and casting techniques were used to develop cast ingots of unrefined andgrain refined structures of Al-7Si alloy. Addition of chemical refiner Al-5Ti-1B to Al-7Si melt could significantly changethe secondary dendritic arm spacing and eutectic Si particle size to 31% and 28%, respectively. In the M-SIMA process, castingots were 60% warm deformed and heat-treated at mushy zone at temperature 585 °C for 30 min. Spherical morphology ofα-Al grain and fine fibrous type eutectic Si are observed after M-SIMA process. Grain size of α-Al and eutectic Si are furtherreduced to 56% and 40% after M-SIMA process of grain refined Al-7Si alloy. Porosity and micro-cracks are also minimizedafter M-SIMA process. Microstructural features of cast and M-SIMA processed alloys were characterized through opticaland scanning electron microscopy. X-ray diffraction techniques reveal the different phases present in the developed alloy. TEM analysis further confirms the presence of TiAl3and Ti7Al5Si14precipitates in grain refined Al-7Si alloy. A significantimprovement of 132% in hardness (HV), 76% in yield strength, 120% in ultimate tensile strength, 125% in elongation tofracture, and 116% in specific ultimate tensile strength are obtained in M-SIMA processed grain refined Al-7Si alloy. Fractographyanalysis reveals the mixed mode of fracture in M-SIMA processed Al-7Si alloy with refined structure comparedto brittle fracture of unrefined cast alloy.
Measurement of the energy dependence of the total photon-proton cross section at HERA
ZEUS Collaboration,Abramowicz, H.,Abt, I.,Adamczyk, L.,Adamus, M.,Aggarwal, R.,Antonelli, S.,Antonioli, P.,Antonov, A.,Arneodo, M.,Aushev, V.,Aushev, Y.,Bachynska, O.,Bamberger, A.,Barakbaev, A.N.,Bar North-Holland Pub. Co 2011 Physics letters: B Vol.697 No.3
The energy dependence of the photon-proton total cross section, σ<SUB>tot</SUB><SUP>γ</SUP><SUP>p</SUP>, was determined from e<SUP>+</SUP>p scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the γp system in the range 194<W<296 GeV. This is the first determination of the W dependence of σ<SUB>tot</SUB><SUP>γ</SUP><SUP>p</SUP> from a single experiment at high W. Parameterizing σ<SUB>tot</SUB><SUP>γ</SUP><SUP>p</SUP>≃W<SUP>2ε</SUP>, ε=0.111+/-0.009(stat.)+/-0.036(syst.) was obtained.
Measurement of the t dependence in exclusive photoproduction of @?(1S) mesons at HERA
ZEUS Collaboration,Abramowicz, H.,Abt, I.,Adamczyk, L.,Adamus, M.,Aggarwal, R.,Antonelli, S.,Antonioli, P.,Antonov, A.,Arneodo, M.,Aushev, V.,Aushev, Y.,Bachynska, O.,Bamberger, A.,Barakbaev, A.N.,Bar North-Holland Pub. Co 2012 Physics letters: B Vol.708 No.1
The exclusive photoproduction reaction γp→@?(1S)p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468 pb<SUP>-1</SUP>. The measurement covers the kinematic range 60<W<220 GeV and Q<SUP>2</SUP><1 GeV<SUP>2</SUP>, where W is the photon-proton centre-of-mass energy and Q<SUP>2</SUP> is the photon virtuality. The exponential slope, b, of the t dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured, yielding b=4.3<SUB>-1.3</SUB><SUP>+2.0</SUP>(stat.)<SUB>-0.6</SUB><SUP>+0.5</SUP>(syst.) GeV<SUP>-2</SUP>. This constitutes the first measurement of the t dependence of the γp→@?(1S)p cross section.
Inclusive-jet photoproduction at HERA and determination of α<sub>s</sub>
ZEUS Collaboration,Abramowicz, H.,Abt, I.,Adamczyk, L.,Adamus, M.,Aggarwal, R.,Antonelli, S.,Antonioli, P.,Antonov, A.,Arneodo, M.,Aushev, V.,Aushev, Y.,Bachynska, O.,Bamberger, A.,Barakbaev, A.N.,Bar North Holland 2012 Nuclear physics, B Vol.864 No.1
Inclusive-jet cross sections have been measured in the reaction ep->e+jet+X for photon virtuality Q<SUP>2</SUP><1 GeV<SUP>2</SUP> and γp centre-of-mass energies in the region 142<W<SUB>γ</SUB><SUB>p</SUB><293 GeV with the ZEUS detector at HERA using an integrated luminosity of 300 pb<SUP>-1</SUP>. Jets were identified using the k<SUB>T</SUB>, anti-k<SUB>T</SUB> or SIScone jet algorithms in the laboratory frame. Single-differential cross sections are presented as functions of the jet transverse energy, E<SUB>T</SUB><SUP>jet</SUP>, and pseudorapidity, η<SUP>jet</SUP>, for jets with E<SUB>T</SUB><SUP>jet</SUP>>17 GeV and -1<η<SUP>jet</SUP><2.5. In addition, measurements of double-differential inclusive-jet cross sections are presented as functions of E<SUB>T</SUB><SUP>jet</SUP> in different regions of η<SUP>jet</SUP>. Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low E<SUB>T</SUB><SUP>jet</SUP> and high η<SUP>jet</SUP>. The influence of non-perturbative effects not related to hadronisation was studied. Measurements of the ratios of cross sections using different jet algorithms are also presented; the measured ratios are well described by calculations including up to O(α<SUB>s</SUB><SUP>2</SUP>) terms. Values of α<SUB>s</SUB>(M<SUB>Z</SUB>) were extracted from the measurements and the energy-scale dependence of the coupling was determined. The value of α<SUB>s</SUB>(M<SUB>Z</SUB>) extracted from the measurements based on the k<SUB>T</SUB> jet algorithm is α<SUB>s</SUB>(M<SUB>Z</SUB>)=0.1206<SUB>-0.0022</SUB><SUP>+0.0023</SUP>(exp.)<SUB>-0.0035</SUB><SUP>+0.0042</SUP>(th.); the results from the anti-k<SUB>T</SUB> and SIScone algorithms are compatible with this value and have a similar precision.
Aniket Chakrabarty,Pritam Chakraborty,Roopam Jain,Vivek Kr. Sahu,N. P. Gurao,H. N. Bar,Niloy Khutia 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10
A novel computational framework has been presented in this work for understanding the mechanical deformation behaviorin additively manufactured parts. AlSi10Mg parts were additively manufactured and investigated for effects on microstructuredue to changes in process parameters. The morphological characteristics of the printed parts were assessed, and 2Dstatistically equivalent representative volume elements (SERVEs) were created and analyzed for deformation under tensioncomputationally with crystal plasticity finite element method (CPFEM) with a combined MATLAB and ABAQUS interactiveframework. For assessing the CPFEM parameters, an interactive ABAQUS and MATLAB environment was implementedusing MATLAB’s genetic algorithm (GA) toolbox. Various results like von Mises stress distribution, maximum in-planestress distribution, and L2-norm of Green Lagrange’s strain were compared, and it was found that the vulnerability of thestructures is related to the change in process or build parameters. CPFEM analyses on 3D microstructures generated throughDREAM. 3D further confirmed the validity of results for CPFEM in 2D. The developed 2D framework also predicted thetexture that correlated well with the tension test findings. Parallely, a finite element framework was developed to study thelocalization effects on AM specimens due to the presence of pores. This work has reported two separate viewpoints in termsof porosity and microstructure.