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1

Hardness, corrosion behavior, and microstructure of Al-Cu-Mg alloy as a function of 0.3 wt.% Zr addition

Saad Karrar, Al-Murshdy Jassim M. Salman

Diagnostyka

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2023

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Vol. 24, No. 1

art. no. 2023104

EN

The effect of adding zirconium (Zr) as an alloying element to Al-Cu-Mg alloy on the hardness and corrosion of this alloy was investigated. The hardness and polarization test results of samples treated for various periods by aging at 423.15 K for 3hr showed a significant increment in the Brinell hardness (HBW) improvement ratio of 115.6% (from 45HBW to 97HBW) and an extreme reduction the corrosion rate of the alloy after Zr adding decrease in the current density by 79.42% (from 56.50 µA cm-2 to 11.63 µA cm-2) with aging for 3 hr compared to the base alloy. The impact of this addition is also reflected in the strengthening, recrystallization, and modification of the grain microstructure. These changes were clearly demonstrated by microscopic testing and proves that the addition of Zr has a considerable synergistic effect causing inhibition of recrystallization and refinement of grain size.

2

Exploration of cellular automata: a comprehensive review of dynamic modeling across biology, computer and materials science

Vodka Oleksii, Shapovalova Mariia

Computer Methods in Materials Science

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2023

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Vol. 23, No. 4

57--80

EN

This paper delves into the expansive world of cellular automata (CA), abstract models of computation comprised of cells that interact based on predefined rules. Originating from John von Neumann’s work in the 1940s, CA has evolved into a multidisciplinary field with applications ranging from mathematical concepts to complex simulations of biological, physical, computer science, material science, and social systems. The paper reviews its historical development, emphasizing John Conway’s influential Game of Life and Burk’s seminar collection. The authors categorize and explore a myriad of CA topics, including self-replicating automata, the universality of computation, compromises in CA, variants, applications in biological systems, fault-tolerant computation, pattern recognition, CA games, fractals, dynamic properties, complexity, image processing, cryptography, bioinformatics, materials modeling, probabilistic automata, and contemporary research. The significance of cellular automata for materials modeling cannot be overstated and considerable attention has been devoted to the issues of modeling nucleation and recrystallization. The review aims to provide a comprehensive resource for both beginners and experts in the field, shedding light on cellular automata’s dynamic and diverse applications in various aspects of life and scientific inquiry.

3

Supercritical antisolvent method for recrystallization of HMX

Thakur Anupama, Taniya, Soni Pramod, Seema Mahesh, Deshwal Seema

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

165--170

EN

Supercritical antisolvent (SAS) method is an emerging technique for particle processing of high energetic materials. The study investigates the recrystallization of high energy material HMX (octahydro- 1,3,5,7-tetranitro-1,3,5,7-tetrazocine) using SAS method. The effect of pressure, solution flow rate, supercritical antisolvent flow rate and temperature on particle size and morphology of HMX crystals has been studied with acetone as solvent and supercritical carbon dioxide as antisolvent. Stable and desirable 𝛽- polymorphic form of HMX could be obtained under certain process conditions and has been confirmed by FTIR spectroscopy. The experimental results show that 𝛽- polymorph of HMX is of rhombohedral morphology with mean particle size of 13.7 μm, as confirmed by SEM and particle size analyzer respectively.

4

Reobservations of Recrystallization and its Effect on Mechanical and Magnetic Properties in a Severely Cold-Rolled Ni-Based Soft Magnetic Alloy

Mahdavi Azizeh, Mashreghi Ali Reza, Hasani Saeed, Kamali Mohammad Reza

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 2

703--717

EN

Despite of extensive researches for decades, there are many unclear aspects for recrystallization phenomenon in the cold rolled Ni-based alloys. Hence, different thermal cycles were conducted in order to determine microstructural evolutions and its effect on the magnetic and mechanical properties of a 90% cold-rolled thin sheet of a Ni-Fe-Cu-Mo alloy (~80 μm). The obtained results revealed that the recrystallization was started at a temperature of 550°C and was completed after 4 hours. An increase in the number of annealing twins was observed with an increase in annealing temperature, which was due to a bulging and long-range migration of grain boundaries during the discontinuous recrystallization. Ordering transformation occurred in the temperature range of 400-600°C and as a result, hardness, yield strength, and UTS were increased, while with an increase in the annealing temperature these mechanical properties were decreased. Maximum toughness was obtained by annealing at 550°C for 4 hours, while the highest elongation was obtained after annealing at 1050°C, where other mechanical properties including toughness, hardness, yield strength, and UTS were decreased due to the grain growth and secondary recrystallization. Moreover, coercivity and remanence magnetization were decreased from 4.5 Oe and 3.8 emu/g for the cold rolled sample to below 0.5 Oe and 0.15 emu/g for the sample annealed at 950°C, respectively.

5

Microstructure refinement mechanism of undercooled Cu55Ni45 alloys

Wang Hongfu, Tang Cheng, An Hongen, Zhao Yuhong

Materials Science Poland

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2021

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Vol. 39, No. 3

319--330

EN

Different undercooling degrees of Cu55Ni45 alloy were obtained by the combination of molten glass purification and cyclic superheating, and the maximum undercooling degree reached 284 K. The microstructure of the alloy was observed by metallographic microscope, and the evolution of microstructure was studied systematically. There are two occasions of grain refinement in the solidification structure of the alloy: one occurs in the case of low undercooling, and the other occurs in the case of high undercooling. Electron backscatter diffraction (EBSD) technology was used to analyze the rapid solidification structure under high undercooling. The features of flat polygonal grain boundary, high proportion of twin boundary, and large proportion of large angle grain boundary indicate recrystallization. The change in microhardness of the alloy under different undercooling degrees was studied by microhardness tester. It was found that the average microhardness decreased sharply at high undercooling degrees, which further confirmed the recrystallization of the solidified structure at high undercooling degrees.

6

Processes simulations with multiscale materials models using a dedicated interface

Smyk Grzegorz, Szeliga Danuta

Computer Methods in Materials Science

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2021

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Vol. 21, No. 4

181--192

EN

The main goal of this work is the integration of in-house software with commercial numerical software based on the finite element method (FEM). The main idea is to develop a universal interface to perform process simulations with multiscale models. The interface allows the combination of external procedures with commercial software with minimum programmer’s work putting in integration. As an example, the model of material recrystallization of steel was implemented, added to the commercial application, and the software was tested for a process defined as a sequence of compression and cooling. The material model takes into consideration each type of recrystallization that occurs during a sequence of thermal and mechanical processing such as static recrystallization (SRX), dynamic recrystallization (DRX), and meta-dynamic recrystallization (MDRX). It allows the prediction of recrystallized volume fraction (X) and grain growth on each step of numerical simulation for each Gauss point in the computation domain. The presented multiscale model of process sequences not only allows to calculate microscale model parameters such as grain growth and recrystallized volume fraction, but also reflects the impact of the microscale model on macroscale parameters.

7

Adiabatic shearing mechanism on Al-4.2%Cu alloy bars subjected to electromagnetic loading

Zhang Xu, Huang Yunkai, Meng Shengfei, Zhu Congcong, Li Guangyao, Cui Junjia

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

393--405

EN

This paper proposed an electromagnetic loading process with the high-speed impact. Al-4.2% Cu alloy bars were used to employ electromagnetic impact (EI) experiments. Deformation mechanism and microstructure evolution of EI samples were revealed by theoretical model and microstructure characterizations. The EI process had impact force (peak value 40 kN) and impact velocity (peak value 6.7 m/s) during a short time period (1.25 ms). Adiabatic shearing mechanism dominated the whole deformation process, causing that significant microstructure characteristic was adiabatic shear bands (ASBs). The theoretical analysis implied that the formation of ASBs was accounted for the radial velocity gradient. Most plastic deformations concentrated in ASBs, and approximately pure shear deformations resulted in adiabatic temperature rise of 0.33–0.42 Tm inside ASBs. The width of ASBs was about 135 μm, in which original equiaxial grains were elongated into laminated sub-structures. TEM observations showed multi-slip systems were simultaneously actuated due to severe shear deformations. High dislocation density and dislocation tangles distributed with the ASBs. Adiabatic temperature rise and distorted energies drove sub-grains rotate into recrystallization grains (70–280 nm) with large angle grain boundaries. The needed maximum time (45 μs) for rotational dynamic recrystallization was far less than that of plastic deformation, indicating that rotational dynamic recrystallization mechanism contributed to the formation of recrystallization grains.

8

Microstructural evaluation of the high-frequency induction welded joints of low carbon steel pipes

Bunsch Adam, Krawczyk Janusz, Matusiewicz Piotr

Advances in Materials Science

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2021

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Vol. 21, nr 4(70)

19--33

EN

The work presents the results of research on the structure of welded joints in the area of heat affected zone (HAZ). Based on precisely performed metallographic tests, the contribution of individual structural components in the area of welds of pipes welded with the induction method was assessed. The volume fraction of individual structural components in various areas of the heat affected zone, the size of the grain formed in the welding process, as well as its shape coefficients were determined. On the basis of metallographic observations, an attempt was made to describe the course of the pressure induction welding process, taking into account the structural changes, phase changes and the recovering and recrystallization processes taking place in this process.

9

Optimisation of LT-GaN nucleation layer growth conditions for the improvement of electrical and optical parameters of GaN layers

Wośko Mateusz

Optica Applicata

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2019

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Vol. 49, nr 1

167--176

EN

In this work we present the influence of low temperature gallium nitride (LT-GaN) nucleation layer deposition and recrystallization conditions on the electrical and optical properties of buffer and active layer of metal–semiconductor field-effect transistor (MESFET) structure. MESFET structures were used to investigate the properties of bulk materials that determine also the performance of many type GaN based devices, like light emitting diodes (LEDs), high electron mobility transistors (HEMTs) and metal–semiconductor–metal (MSM) detectors. The set of n-GaN/u-GaN/sapphire structures using different nucleation LT-GaN layers thickness and different annealing times was deposited using AIXTRON CCS epitaxial system. In contrast to typical procedure, the high resistive GaN buffer layer was not obtained by intentional Fe/Mg doping, but by specific adjustment of GaN nucleation conditions and recrystallization process parameters that introduce carbon atoms in epitaxial layers, that serve as donors. Generally, low pressure (below 200 mbar) in a reactor chamber, during initial stages of nucleation and recrystallization as well as HT-GaN epitaxy, promotes the growth of high resistive material. Obtained results show that annealing/recrystallization time of LT-GaN has a significant impact on the electrical and optical properties of GaN buffer layers. Longer annealing periods tend to promote crystallization of material with higher electron mobility and higher Si dopant incorporation/activation while maintaining high resistivity in u-GaN buffer area. It was shown that the dimensions of the GaN islands, that could be influenced by the duration of an annealing step of LT-GaN growth, have no impact on the HT-GaN buffer layer coalescence process and material resistivity, but influences mainly electrical properties of active n-GaN layer. Author suggests that the key parameters that are determining the buffer resistivity are the pressure and temperature during LT-GaN annealing and buffer layer coalescence. The influence of GaN island diameters, after LT-GaN annealing, on the u-GaN resistivity was not confirmed.

10

Characterisation of Purified Gypsum and Insoluble Impurities Obtained from Phosphogypsum Waste

Kaludjerovic Lazar, Isek Josip, Vukovic Nikola, Milosevic Maja

Inżynieria Mineralna

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2019

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R. 21, nr 1

73--78

EN

In this study, the chemical and phase composition of two samples of phosphogypsum from the waste dumps of the Industry of Chemical Products “Elixir – Prahovo” (Serbia) were examined, as well as the possibility of recrystallization of gypsum from an aqueous suspension of phosphogypsum. The negative effect of higher temperatures on the solubility of calcium sulfate (13.08 mmol/dm3 at 95°C vs. 15.43 mmol/dm3 at 40°C) was utilized. In several repeated cycles, calcium sulfate component was progressively dissolved in water at room temperature and then precipitated at 100°C, using the same liquid phase throughout the experiment. Therefore, phosphogypsum was separated into recrystallized (purified) gypsum, insoluble residue and supernatant, and the mass balance for the experiment was calculated. Elemental, XRD and SEM-EDS analyses were performed on raw phosphogypsum, purified gypsum and insoluble residue. The whiteness of raw phosphogypsum and purified gypsum were determined and compared. The main objective of the study was to investigate the nature of insoluble impurities, in order to define and optimize the methods for their removal during a potential industrial processing of phosphogypsum.

PL

W artykule przedstawiono skład chemiczny i fazowy dwóch próbek fosfogipsu ze składowisk odpadów Przemysłu Chemicznego „Elixir – Prahovo” (Serbia), a także możliwość rekrystalizacji gipsu z zawiesiny wodnej fosfogipsu. Wykorzystano negatywny wpływ wyższych temperatur na rozpuszczalność siarczanu wapnia (13,08 mmol/ dm3 w 95°C wobec 15,43 mmol/dm3 w 40°C). W kilku powtarzających się cyklach siarczanu wapnia stopniowo rozpuszczano w wodzie w temperaturze pokojowej, a następnie wytrącano w 100°C, stosując tę samą fazę ciekłą w całym doświadczeniu. W ten sposób fosfogips został rozdzielony na rekrystalizowany (oczyszczony) gips, nierozpuszczalną pozostałość i supernatant, kolejno obliczono bilans masy dla doświadczenia. Analizy elementarne, XRD i SEM-EDS przeprowadzono na surowym fosfogipsie, oczyszczonym gipsie i nierozpuszczalnej pozostałości. Określono i porównano biel surowego i oczyszczonego gipsu. Głównym celem pracy było zbadanie natury nierozpuszczalnych zanieczyszczeń w celu określenia i zoptymalizowania metod ich usuwania podczas przemysłowego przetwarzania fosfogipsu.

11

Friction Weldability of UFG 316L Stainless Steel

Skowrońska B., Chmielewski T., Pachla W., Kulczyk M., Skiba J., Presz W.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

1051--1058

EN

The broad range applications of Ultra-Fine Grained metals is substantially limited by the lack of a welding method that allows them to be joined without losing the strong refinement of structure. From this point of view, the solid state welding processes are privileged. Friction welding tests were carried out on UFG 316L stainless steel. A joining process at high temperature activates the recrystallization, therefore the friction welding parameters were selected according to the criterion of the lowest degree of weakness due to recrystallization in the heat affected zone. In order to characterize the structure of basic material and selected areas of the obtained joint, were performed SEM, TEM and metallographic examinations in terms of hardness and range of softening of the material and tensile test. Despite the short time and relatively low welding temperature, results of the test by scanning electron microscopy and transmission electron microscopy confirmed the loss of the primary ultrafine structure in the Heat Affected Zone of welded joint.

12

Analysis of the strengthening and recrystallization of electrolytic copper (Cu-ETP) and oxygen free copper (Cu-OF)

Zasadzińska Małgorzata, Knych Tadeusz, Strzępek Paweł, Jurkiewicz Bartosz, Franczak Krystian

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

186--193

EN

The research paper studies the strengthening and the kinetics of recrystallization of ETP copper and OF copper. This research covers a wide scope of strain hardening specific for the manufacturing of microwires (true strain of the order of 5) and the range of temperatures and times of the recrystallization process referring to the real life conditions occurring in advanced technologies of microwires’ manufacturing. As a result of the performed tests, it was established that the recrystallization temperature of ETP copper is lower than the recrystallization temperature of OF copper regardless of the recrystallization time as the recrystallisation effect can be achieved after about 10–30 s regardless of the copper grade.

13

Re-crystallization of Silicon during Rapid Thermal Treatment

Gorushko V., Omelchenko A., Pilipenko V., Solodukha V., Opielak M., Żukowski P., Kołtunowicz T.

Przegląd Elektrotechniczny

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2018

|

R. 94, nr 5

196--198

EN

It is by means of the Auger-spectroscopy, spectral ellipsometry, X-ray diffraction that for the first time an opportunity was shown of applying the rapid thermal treatment for removal of the disrupted layer on the working surface of the silicon wafers after the chemical-mechanical polishing owing to its solid-phase re-crystallization.

PL

Dzięki użyciu spektroskopii Augera, elipsometrii spektralnej oraz dyfrakcji rentgenowskiej po raz pierwszy przedstawiona została możliwość zastosowania szybkiego termicznego usuwania uszkodzonej warstwy na powierzchni roboczej wafli silikonowych, powstałych po chemiczno-mechanicznym polerowaniu, za pośrednictwem jego rekrystalizacji w fazie stałej.

14

Struktura i własności mechaniczne prętów ze stopu AA7010 w stanach O i T6

Pieła K., Sak T., Błaż L., Woźnicki A., Ostachowski P., Łagoda M.

Obróbka Plastyczna Metali

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2018

|

T. 29, nr 2

169--192

PL

Wyciskane na gorąco pręty ze stopu aluminium AlZn6,43Mg2,23Cu1,78 (AA7010) poddano, kolejno, odkształceniu drogą ciągnienia, wyżarzaniu na stan miękki (O) oraz procesowi utwardzania wydzieleniowego na stan T6. Próbki ciągnionych prętów o zróżnicowanej wielkości odkształcenia (5–67%) poddano wyżarzaniu w szerokim zakresie temperatury (300–465°C) i czasu wyżarzania (1–10 h). Zastosowane warunki wyżarzania aktywizują procesy zdrowienia, rekrystalizacji i rozrostu ziarna. Wykazano, że proces rekrystalizacji prętów, wyżarzanych na stan O, jest kontrolowany przez dystrybucję i stabilność termiczną wydzieleń fazy czynnej η (MgZn2). Wyżarzanie w temperaturze niższej od temperatury granicznej rozpuszczalności fazy czynnej (poniżej 400°C) zachowuje liniowy rozkład wydzieleń tej fazy, co utrudnia migrację frontów rekrystalizacji w kierunku promieniowym prętów i prowadzi do formowania ziaren o dużej anizotropii kształtu. Wzrost temperatury wyżarzania powoduje istotne przyśpieszenie procesu rozpuszczania wydzieleń fazy czynnej, w wyniku czego następuje uwolnienie frontów rekrystalizacji, a w konsekwencji formowanie ziaren o znacznie mniejszej anizotropii kształtu oraz zmiana dystrybucji i morfologii wydzieleń tej fazy. Stwierdzono ponadto, że – pomimo znaczących różnic strukturalnych – wielkość odkształcenia praktycznie nie wpływa na własności wytrzymałościowe i plastyczne prętów zarówno w stanie O, jak i w większości przypadków w stanie T6. Potwierdzono eksperymentalnie słabą zależność własności wytrzymałościowych Al i jego stopów od wielkości ziarna oraz istotny wpływ rodzaju i dystrybucji prowydzieleń (wydzieleń) faz umacniających na własności mechaniczne tych stopów w stanie T6.

EN

The hot extruded rods of aluminum alloy AlZn6,43Mg2,23Cu1,78 (AA7010) were subjected to, in sequence, deformation by drawing, annealing to the O temper and precipitation hardening to the T6 temper. The samples of rods drawn with the variable strain value (area reduction of 5–67%), were annealed in the wide range of temperatures (300–465°C) and times (1–10 h). The applied annealing conditions activate recovery, recrystallization and grain growth processes. It was shown that recrystallization process of rods annealed to the O temper is controlled by a distribution and thermal stability of active phase η (MgZn2). The annealing at the temperatures lower than the temperature of active phase solubility limit (below 400°C) maintains a linear distribution of this phase precipitates. It hinders recrystallization fronts migration in radial direction of rods and leads to formation of grains with considerable shape anisotropy. The increase of annealing temperature results in significant acceleration of the active phase precipitates dissolution process, whereby a release of recrystallization fronts and in consequence formation of grains with appreciable lower shape anisotropy, as well as change of distribution and morphology of mentioned phase precipitates take place. Moreover, it was found that – despite considerable structural differences – strain value during drawing hardly influences strength and plastic properties of the rods in the O temper, as well as in the most cases in the T6 temper. The weak relationship between grain size and strength properties of Al and its alloys, as well as significant influence of hardening phases pre-precipitates (precipitates) type and distribution on mechanical properties of these alloys in the T6 temper were experimentally confirmed.

15

Preliminary results of 57Fe Mössbauer spectroscopy of metamict samarskite after one-hour high temperature annealing in argon

Malczewski D., Grabias A.

Nukleonika

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2017

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Vol. 62, No. 2

141--144

EN

The preliminary results of 57Fe Mössbauer spectroscopy and X-ray diffraction (XRD) of fully metamict samarskite dated at ~1500 Ma, which absorbed -dose of 6.5 × 1017 α-decay mg–1, are reported after one-hour annealing at 673, 873, 1173 and 1373 K in argon atmosphere. Metamict minerals contain radioactive elements that degrade their crystal structures over geological time. All the Mössbauer spectra obtained can be fitted to two quadrupole doublets assigned to Fe2+ and Fe3+ in octahedral positions. The relative contribution of Fe2+ (Fe2+/Fe) reaches a minimum of 0.10 at 1173 K.

16

Thermal Stability of AA1050 Aluminum Alloy after Equal Channel Angular Pressing

Koprowski P., Bogucki R., Bieda M., Kawałko J., Sztwiertnia K.

Archives of Metallurgy and Materials

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2017

|

Vol. 62, iss. 2A

777--786

EN

The annealing behavior of AA1050 aluminum alloy deformed by equal-channel angular pressing (ECAP) was studied experimentally. The material was subjected to extrusion through die with channels intersecting at an 90° angle. Samples were pressed for up to 8 passes using route BC, then cut into slices and subsequently annealed for 1 hour at temperatures from 100°C to 350°C. Hardness measurements were performed on each slice. Microstructure of material was analyzed in the longitudinal section by means of Electron Backscatter Diffraction system in a scanning electron microscope (EBSD/SEM). From the obtained sets of Kikuchi diffraction patterns orientation maps and Image Quality maps were determined. Grain size, disorientation distributions and crystallographic texture were also estimated. ECAP caused significant improvement of hardness, with stabilization after 4 passes. Refinement of microstructure was obtained with the increasing amount of passes. Material properties were stable during annealing at temperatures lower than 150°C. Annealing at higher temperatures caused a decrease in hardness corresponding to an increase of the grain size.

17

The characteristic of deformability and quantitative description of the microstructure of hot-deformed Ni-Fe superalloy

Ducki K. J., Rodak K., Mendala J., Wojtynek L.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 1

297--302

EN

The paper presents the results of research concerning the influence of hot plastic working parameters on the deformability and microstructure of a Ni-Fe superalloy. The research was performed on a torsion plastometer in the range of temperatures of 900-1150°C, at a strain rates 0.1 and 1.0 s-1. Plastic properties of the alloy were characterized by the worked out flow curves and the temperature relationships of flow stress and strain limit. The structural inspections were performed on microsections taken from plastometric samples after so-called “freezing”. The stereological parameters as the recrystallized grain size, inhomogenity and grain shape have been determined. Functional relations between the Zener-Hollomon parameter and the maximum yield stress and the average grain area have been developed and the activation energy for hot working has been estimated.

18

Wpływ stabilizatorow na ograniczenie rekrystalizacji w lodach typu sorbet

Kamińska-Dwórznicka A., Samborska K., Jakubczyk E., Gondek E.

Przemysł Spożywczy

|

2016

|

T. 70, nr 9

32--35

PL

W artykule porownano wpływ mieszanek stabilizujących na przebieg procesu rekrystalizacji w sorbetach truskawkowych bezpośrednio po przygotowaniu oraz po miesiącu przechowywania w temp. -18°C. Do badań wykorzystano zdjęcia kryształów lodu wykonane za pomocą mikroskopu i kamery Nikon przystosowanych do pracy w ujemnej temperaturze. Następnie zdjęcia przeanalizowano stosując program NIS Elements D i określono wymiary średnic powstałych kryształów lodu. W badaniu jako dodatki stabilizujące zastosowano preparaty żelatyny wieprzowej, gumy guar, gumy ksantanowej, mączki chleba świętojańskiego, kappa-karagenu oraz alkoholu, naturalne białko ochronne AFP i przemysłową mieszankę stabilizatorów oznaczaną jako CRE. Stwierdzono, że dodatek AFP (w połączeniu z żelatyną i gumą guar) oraz mieszanka CRE najskuteczniej hamowały proces rekrystalizacji, a kryształy lodu po miesiącu przechowywania nie były większe niż 15 μm.

EN

The aim of the present paper was to evaluate and compare the effect of stabilizing mixtures on the run of recrystallization process in strawberry sorbet directly after preparation and after a month of storage at -18°C, using a microscope and a Nikon camera adapted to take pictures at the temperature below zero. The images were then analyzed, using NIS Elements D program to determine equivalent ice crystals’ diameters. In the present study, gelatin, guar gum, xanthan, locust bean gum, κ – carrageenan, alcohol, and natural protective protein, called AFP and the mixtures of stabilizers under the trade name CRE were used as stabilizing additives. It was found that the addition of AFP (in combination with gelatin and guar gum) and CRE mixture inhibited most effectively the recrystallization process and the ice crystals after one month of storage did not exceed 15 μm.

19

Recent Trends in Metal Forming: From Process Simulation and Microstructure Control In Classical Forming Processes to Hybrid Combinations Between Forming and Additive Manufacturing

Bambach M.

Journal of Machine Engineering

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2016

|

Vol. 16, No. 2

5--17

EN

This paper describes some recent trends in metal forming such as isothermal forging of titanium aluminides and process combinations between metal forming and additive manufacturing. These trends rely on accurate process and material models for process design. Process and material models must hence be able to track the microstructure evolution in complex materials such as titanium aluminides as well as predict the microstructure evolution along process histories with multiple deformation and/or heat input steps. In models for such processes, JMAK-type kinetics for and phase transformation are still common. For processes involving deformation and heat, the accuracy, consistency and limits of JMAK-type models are discussed. It is shown that the consistency of DRX models as well as the stability of model predictions in multi-stage processes require further attention.

20

RCAFE Based Numerical Model of Dynamic Recrystallization

Legwand A., Sitko M., Perzyński K., Madej Ł.

Journal of Machine Engineering

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2016

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Vol. 16, No. 2

52--60

EN

The main goal of the paper is dedicated to proper arrangement of the Finite Element (FE) and Random Cellular Automata (RCA) methods in order to develop numerical model of dynamic recrystallization (DRX) and therefore to simulate microstructure morphology changes during plastic deformation at elevated temperatures. In the approach, Finite Element solver provides information on equivalent stress and strain fields after subsequent time steps. Then these data are transferred to RCA model, which is responsible for evaluation of corresponding microstructure morphology evolution and dislocation density changes. Finally, information from the CA part is send back to the FE solver as an input for the next time step. As a result, a fully coupled RCAFE model to simulate progress of DRX is established. The present paper is directly focused on development of algorithms and methods to transfer input/output data between both FE and RCA models. The developed communication protocol is based on the Abaqus VUMAT subroutine. Examples of obtained results from the developed model are also presented to highlight its potential.