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Number of results: 10
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Abstract

In this study, the extrusion characteristics of Al-2Zn-1Cu-0.5Mg-0.5RE alloys at 450, 500, and 550℃ were investigated for the high formability of aluminum alloys. The melt was maintained at 720℃ for 20 minutes, then poured into the mold at 200℃ and hot-extruded with a 12 mm thickness bar at a ratio of 38:1. The average grain size was 175.5, 650.1, and 325.9 μm as the extrusion temperature increased to 450, 500 and 550℃, although the change of the phase fraction was not significant as the extrusion temperature increased. Cube texture increased with the increase of extrusion temperature to 450, 500 and 550℃. As the extrusion temperature increased, the electrical conductivity increased by 47.546, 47.592 and 47.725%IACS, and the tensile strength decreased to 92.6, 87.5, 81.4 MPa. Therefore, the extrusion temperature of Al extrusion specimen was investigated to study microstructure and mechanical properties.

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Authors and Affiliations

Yong-Ho Kim
ORCID: ORCID
Hyo-Sang Yoo
ORCID: ORCID
Kyu-Seok Lee
Sung-Ho Lee
Hyeon-Taek Son
ORCID: ORCID
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Abstract

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.
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Authors and Affiliations

A. Szewczyk
1
ORCID: ORCID
M. Faryna
1
ORCID: ORCID
A. Wójcik
1
ORCID: ORCID
Wojciech Maziarz
ORCID: ORCID
R. Chulist
1
ORCID: ORCID

  1. Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059, Kraków, Poland
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Abstract

In a vacuum Bridgman-type furnace, under an argon atmosphere, directionally solidified sample of Fe - C alloy was produced. The pulling

rate was v = 83 μm/s (300 mm/h) and constant temperature gradient G = 33,5 K/mm. The microstructure of the sample was examined on

the longitudinal section using an Optical Microscope and Scanning Electron Microscope. The X-ray diffraction and electron backscatter

diffraction technique (EBSD) have been used for the crystallographic analysis of carbide particles in carbide eutectic. The

X-ray diffraction was made parallel and perpendicular to the axis of the goniometer. The EBSD shows the existence of iron carbide Fe3C

with orthorhombic and hexagonal structure. Rapid solidification may cause a deformation of the lattice plane which is indicated by

different values of the lattice parameters. Such deformation could also be the result of directional solidification. Not all of the peaks in

X–ray diffractograms were identified. They may come from other iron carbides. These unrecognized peaks may also be a result of the

residual impurity of alloy.

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Authors and Affiliations

M. Trepczyńska-Łent
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Abstract

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.
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Authors and Affiliations

I. Mania
1
ORCID: ORCID
H. Paul
1
ORCID: ORCID
R. Chulist
1
ORCID: ORCID
P. Petrzak
1
ORCID: ORCID
M. Miszczyk
1
ORCID: ORCID
M. Prażmowski
2
ORCID: ORCID

  1. Polish Academy of Sciences, Institute of Metallurgy and Materials Science, 25 Reymonta Str., 30-059 Krakow, Poland
  2. Opole University of Technology, Faculty of Mechanics, 76 Prószkowska Str., 45-758 Opole, Poland
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Abstract

Analysis of a crystallographic texture (a preferred orientation) effect on cavitation wear resistance of the as-cast CuZn10 alloy, has been conducted in the present paper. The experiment was conducted on the CuZn10 alloy samples with <101>//ND or <111>//ND preferred orientations (where the ND denotes direction that is perpendicular to the exposed surface). The cavitation resistance examinations have been carried out on three different laboratory stands (namely, vibration, jet-impact and flow stands) that are characterized by a various intensity and a way of cavitation’s excitement. Obtained results point towards a higher cavitation resistance of the CuZn10 alloy with the <111> // ND preferred orientation.
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Authors and Affiliations

W. Polkowski
R. Jasionowski
D. Zasada
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Abstract

This study utilizes Ti-8Nb-4Co alloys added to different proportions of Mo2C powders (1, 3, and 5 mass%) by the vacuum sintering process of powder metallurgy and simultaneously vacuum sinters the alloys at 1240, 1270, 1300, and 1330°C for 1 h, respectively. The experimental results indicate that when 3 mass% Mo2C powders were added to the Ti-8Nb-4Co alloys, the specimens possessed the optimal mechanical properties after sintering at 1300°C for 1 h. The relative density was 98.02%, and the hardness and TRS were enhanced to 69.6 HRA and 1816.7 MPa, respectively. In addition, the microstructure of vacuum sintered Ti-8Nb-4Co-3Mo2C alloys has both α and β-phase structures, as well as TiC precipitates. EBSD results confirm that the Mo 2C in situ produced TiC during the sintering process and was uniformly dispersed in the grain boundary. Moreover, the reduced molybdenum atom acted as a β-phase stabilizing element and solid-solution in the titanium matrix.
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Authors and Affiliations

Shih-Hsien Chang
1
ORCID: ORCID
Kun Jie Liao
1
ORCID: ORCID
Kuo-Tsung Huang
2
ORCID: ORCID
Cheng Liang
1
ORCID: ORCID

  1. National Taipei University of Technology, Department of Materials and Miner al Resources Engineering, Taipei 10608, Taiwan, ROC
  2. National Kangshan Agricultural Industrial Senior High School, Department of Auto-Mechanics, Kaohsiung 82049, Taiwan, ROC
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Abstract

Two strength-age hardening aluminum-lithium alloys: Al-2.3wt%Li and Al-2.2wt%Li-0.1wt%Zr in two different heat treatment conditions: solution state (S) and additionally in aging state (A) were severely plastically deformed by rolling with cyclic movement of rolls (RCMR) method to produce ultrafine – grained structure. Two thermo-mechanical treatments were used: (S+A+RCMR) and (S+RCMR+A+RCMR). To investigate the combined effect of plastic deformation and heat treatment, tensile tests were performed. Microstructural observations were undertaken using scanning transmission electron microscopy (STEM), and scanning transmission electron microscopy (SEM) equipped with electron backscattering diffraction detector (EBSD). Based on the obtained results, it can be deduced that maximum mechanical properties as: yield strength (YS) and ultimate tensile strength (UTS) could be achieved when the microstructure of alloys is in (S+A+RCMR) state. For samples in (S+RCMR+A+RCMR) state, ductility is higher than for (S+A+RCMR) state. The microstructural results shows that the favourable conditions for decreasing grain size of alloys is (S+A+RCMR) state. Additionally, in this state is much greater dislocation density than for (S+RCMR+A+RCMR) state. The microstructure of alloys in (S+RCMR+A+RCMR) state is characterized by grains/subgrains with higher average diameter and with higher misorientation angles compared with (S+A+RCMR) state.

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Authors and Affiliations

A. Brzezińska
A. Urbańczyk-Gucwa
R. Molak
K. Rodak
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Abstract

The results are based on two experimental high-manganese X98MnAlSiNbTi24-11 and X105MnAlSi24-11 steels subjected to thermo-mechanical treatment by hot-rolling on a semi-industrial processing line. The paper presents the results of diffraction and structural studies using scanning and transmission electron microscopy showing the role of Nb and Ti micro-additives in shaping high strength properties of high-manganese austenitic-ferritic steels with complex carbides. The performed investigations of two experimental steels allow to explain how the change cooling conditions after thermo-mechanical treatment of the analysed steels affects the change of their microstructure and mechanical properties. The obtained results allow assessing the impact of both the chemical composition and the applied thermo-mechanical treatment technology on the structural effects of strengthening of the newly developed steels.

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Authors and Affiliations

L. Sozańska-Jędrasik
J. Mazurkiewicz
W. Borek
K. Matus
B. Chmiela
M. Zubko
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Abstract

This study mixes four different powders to produce Ti-6Cu-8Nb-xCr3C2 (x = 1, 3, and 5 mass%) alloys in three different proportions. The experimental results reveal that when 5 mass% Cr3C2 was added to the Ti-6Cu-8Nb alloys, the specimen possessed optimal mechanical properties after sintering at 1275°C for 1 h. The relative density reached 98.23%, hardness was enhanced to 67.8 HRA, and the transverse rupture strength (TRS) increased to 1821.2 MPa, respectively. The EBSD results show that the added Cr3C2 in situ decomposed into TiC and NbC during the sintering process, and the generated intermetallic compounds (Ti2Cu) were evenly dispersed in the Ti matrix. Furthermore, the reduced Cr atom acts as a β-phase stabilizing element and solid-solution in the Ti matrix. Consequently, the main strengthening mechanisms of the Ti-6Cu-8Nb-xCr3C2 alloys include dispersion strengthening, solid-solution strengthening, and precipitation hardening.
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Authors and Affiliations

Shih-Hsien Chang
1
ORCID: ORCID
Chen-Yu Weng
1
ORCID: ORCID
Kuo-Tsung Huang
2
ORCID: ORCID
Cheng Liang
1
ORCID: ORCID

  1. National Taipei University of Technology, Department of Materials and Mineral Resources Engineering, Taipei 10608, Taiwan, ROC
  2. National Kangshan Agricultural Industrial Senior High School, Department of Auto-Mechanics, Kaohsiung 82049, Taiwan, ROC

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