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1

Thermoplastic hardened Cu-Ni-Si-Ag alloy

100%

Krupińska B. , Chulist R. , Kondracki M. , Labisz K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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tom Vol. 71, nr 2

art. no. e145683

EN

The paper aims to investigate the influence of silver addition on the microstructure of CuNi2Si1 alloys. The investigated copper alloy was cast and then supersaturated, plastically deformed on the Gleeble 3800 simulator and finally aged. Structural changes were examined using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Orientation mapping was completed with FEI Quanta 3D field emission gun scanning electron microscope (SEM) equipped with TSL electron backscattered diffraction (EBSD) system. The effect of structural and microstructural changes on hardness and conductivity was also investigated. Based on the mechanical tests it was found that the mechanical properties and conductivity are improved due to heat and plastic treatment. It was also found that the precipitation hardening raises the hardness to the level of 40% whilst an increase in conductivity by 20% is observed.

2

Precise Orientation Control of Single Crystalline NiMnGa-Based Alloys by in-situ EBSD Analysis

88%

Szewczyk A. , Faryna M. , Wójcik A. , Maziarz W. , Chulist R.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 3

1171--1175

EN

The article presents a precise method for the orientation process of NiMnGa-based single crystals. For this method, a scanning electron microscope equipped with an EBSD camera and a heating stage allowing temperatures exceeding 873 K was used. The orientation process was carried out in both the high-temperature austenite phase and in the room-temperature martensite phase. The facilities allowed for determining the orientation of a single grain of austenite at elevated temperatures as well as the orientation of particular martensitic variants at room temperature. A practically perfect cubic orientation was obtained in the austenitic case with a deviation of about 1° while the samples oriented in the martensitic phase deviated from the desired orientation by 4.5-5.2°. Additionally, the training process of single crystals was carried out in order to show the influence of the orientation process on twinning stress.

3

The Influence of γ' Precipitates on the Structural Stability of FeNi-CoAlTa and FeNiCoAlTaB Single Crystals After Cyclic Superelastic Deformation

88%

Wójcik A. , Chulist R. , Szewczyk A. , Dutkiewicz J. , Maziarz W.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 3

1157--1164

EN

Two single crystals with compositions Fe-Ni-Co-Al-Ta and Fe-Ni-Co-Al-Ta-B were selected and fabricated by Bridgman method. Subsequently, ingots were homogenized, oriented and subjected to a two-step heat treatment process in order to obtain fine and coherent γ' precipitates. Subsequently, superelastic cycling experiments were performed at 77 K. The next step included detailed microstructural characterization using transmission electron microscopy and high-energy synchrotron X-ray diffraction measurements together with Rietveld refinement. The results show that the number of fully reversible superelastic strains is very sensitive to the size of γ' precipitates. The smaller (3 nm) γ' precipitates ensured more superelastic response compared to material with larger γ' particles size (5 nm), in which the material did not receive its original shape after 10 cycles even after being heated.

4

Crystal Lattice Rotations Induced by Shear Banding in fcc Metals Deformed at High Strain Rates

75%

Mania I. , Paul H. , Chulist R. , Petrzak P. , Miszczyk M. , Prażmowski M.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 1

319--329

EN

In this paper, the microstructural and texture changes in polycrystalline CuZn30 alloy, copper, and AA1050 aluminium alloy have been studied to describe the crystal lattice rotation during shear bands formation. The hat-shaped specimens were deformed using a drop-hammer at the strain rate of 560 s-1. Microstructure evolution was investigated using optical microscopy, whereas texture changes were examined with the use of a scanning electron microscope equipped with the EBSD facility. The microstructural observations were correlated with nanohardness measurements to evaluate the mechanical properties of the sheared regions. The analyses demonstrate the gradual nature of the shear banding process, which can be described as a mechanism of the bands nucleation and then successive growth rather than as an abrupt instability. It was found that regardless of the initial orientation of the grains inside the sheared region, a well-defined tendency of the crystal lattice rotation is observed. This rotation mechanism leads to the formation of specific texture components of the sheared region, different from the one observed in a weakly or non-deformed matrix. During the process of rotation, one of the {111} planes in each grain of the sheared region ‘tends’ to overlap with the plane of maximum shear stresses and one of the <110> or <112> directions align with the shear direction. This allows slip propagation through the boundaries between adjacent grains without apparent change in the shear direction. Finally, in order to trace the rotation path, transforming the matrix texture components into shear band, rotation axis and angles were identified.

5

Structural Characterization and Properties of Al/Fe Multi-Layer Composites Produced by Hot Pressing

63%

Kowalski W. , Paul H. , Mania I. , Petrzak P. , Czaja P. , Chulist R. , Góral A. , Szlezynger M.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 1

137--144

EN

This study aimed to develop Fe/Al multilayered metallic/intermetallic composites produced by hot pressing under an air atmosphere. Analyses were carried out on the composite plates made up of alternatively situated sheets of AA1050 aluminum alloy and DN04 low carbon steel, which were annealed at 903 K for 2, 5, and 10 h. Annealing was performed to obtain reaction layers of distinct thickness. The samples were examined using X-Ray diffraction and scanning and transmission electron microscope equipped with an energy-dispersive X-Ray spectrometer. To correlate the structural changes with mechanical properties, microhardness measurements in near-the-interface layers were performed. All the reaction layers grew with parabolic kinetics with η-Al5Fe2 intermetallic phase as the dominant component. After annealing for 5 and 10 hours, a thin sublayer of θ-Al13Fe4 phase was also detected.

6

TEM, HREM, L-TEM Studies of Fe-Based Soft Magnetic Melt-Spun Ribbons Subjected to Ultra-Rapid Annealing Process

63%

Maziarz W. , Kolano-Burian A. , Kowalczyk M. , Błyskun P. , Chulist R. , Czaja P. , Szlezynger M. , Wójcik A.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 3

1165--1170

EN

In the present work, we performed the ultra-rapid annealing (URA) process for amorphous Fe78Ni8B14 melt-spun ribbons in order to obtain fine excellent microstructure assuring the best soft magnetic properties. Several microscopic methods mainly based on transmission electron microscopy (TEM) and Lorentz TEM (L-TEM) were applied for detailed studies of the microstructure and magnetic domains structure. The investigation revealed that the optimized parameters of the URA process (500°C/0.5-5 s) lead to outstanding soft magnetic properties. A mixture containing close to 50% amorphous phase and 50% α-Fe nanocrystals of size up to 30 nm has been already obtained after annealing for 3 s. These annealing conditions appear to be the most suitable in terms of microstructure providing the best magnetic properties.

7

Microstructure evolution of pure titanium during hydrostatic extrusion

63%

Wojtas D. , Maj Ł. , Wierzbanowski K. , Jarzębska A. , Chulist R. , Kawałko J. , Trembecka-Wójciga K. , Bieda-Niemiec M. , Sztwiertnia K.

Archives of Civil and Mechanical Engineering

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2023

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tom Vol. 23, no. 1

art. no. e9, 2023

EN

Regarding severely deformed materials of potentially high applicability in various industry branches, their microstructure evolution during processing is of vast significance as it enables to control or adjust the most essential properties, including mechanical strength or corrosion resistance. Within the present study, the microstructure development of commercially pure titanium (grade 2) in the multi-stage process of hydrostatic extrusion has been studied with the use of the well-established techniques, involving electron backscatter diffraction as well as transmission electron microscopy. Microstructural deformation-induced defects, including grain boundaries, dislocations, and twins, have been meticulously analyzed. In addition, a special emphasis has been placed on grain size, grain boundary character as well as misorientation gradients inside deformed grains. The main aim was to highlight the microstructural alterations triggered by hydroextrusion and single out their possible sources. The crystallographic texture was also studied. It has been concluded that hydrostatically extruded titanium is an exceptionally inhomogeneous material in terms of its microstructure as evidenced by discrepancies in grain size and shape, a great deal of dislocation-type features observed at every single stage of processing and the magnitude of deformation energy stored. Twinning, accompanied by grain subdivision phenomenon, was governing the microstructural development at low strains; whereas, the process of continuous dynamic recrystallization came to the fore at higher strains. Selected mechanical properties resulting from the studied material microstructure are also presented and discussed.