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Wyświetlanie 1-10 z 10
Tytuł:
Microstructure and Mechanical Properties of Al-3 Vol% CNT Nanocomposites Processed by High-Pressure Torsion
Autorzy:
Asgharzadeh, H.
Kim, H. S.
Powiązania:
https://bibliotekanauki.pl/articles/354004.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high-pressure torsion
aluminum
CNT
microstructure
mechanical properties
Opis:
Al-3 vol% CNT nanocomposites were processed by high-pressure torsion (HPT) at room temperature under the pressure in the range of 2.5-10 GPa for up to 10 turns. Optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM) were used to investigate the microstructural evolutions upon HPT. Mechanical properties of the HPT-processed disks were studied using tensile tests and microhardness measurements. The results show gradual evolutions in the density, microstructure, and hardness with increasing the number of turns and applied presure. Nanostructured and elongated Al grains with an average grain thickness of ~40 nm perpendicular to the compression axis of HPT and an aspect ratio of ~3 are formed after 10 turns under 6 GPa. Evaluating the mechanical properties of the 10-turn processed Al/CNT nanocomposites indicates a tensile strength of 321 MPa and a hardness of 122 Hv. The tensile fracture surface of the Al/CNT nanocomposite mostly demonstrates a smooth fracture manner with fine dimples resulting in a low tensile ductility of ~1.5%.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1109-1112
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication Of Zn4Sb3 Alloys By A Combination Of Gas-Atomization And Spark Plasma Sintering Processes
Wytwarzanie i konsolidacja proszków stopowych zn4sb3 przez kombinację procesów atomizacji gazowej i spiekania
Autorzy:
Dharmaiah, P.
Kim, H.-S.
Lee, L. H.
Hong, S.-J.
Powiązania:
https://bibliotekanauki.pl/articles/355894.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gas atomization
microstructure
spark plasma sintering (SPS)
X-ray diffraction
atomizacja gazowa
mikrostruktura
SPS
spiekanie plazmowe
analiza rentgenowska (XRD)
Opis:
In this study, single phase polycrystalline Zn4Sb3 as well as 11 at.% Zn-rich Zn4Sb3 alloy having ε-Zn4Sb3 (majority phase) and Zn (minority phase) phases bulk samples produced by gas-atomization and subsequently consolidated by spark plasma sintering (SPS) process. The crystal structures were analyzed by X-ray diffraction (XRD) and cross-sectional microstructure were observed by the scanning electron microscopy (SEM). The internal grain microstructure of 11at.% Zn-rich Zn4Sb3 powders shows lamellar structure. Relative density, Vickers hardness and crack lengths were measured to investigate the effect of sintering temperature of Zn4Sb3 samples which are sintered at 653, 673 and 693 K. Relative density of the single phase bulk Zn4Sb3 sample reached to 99.2% of its theoretical density. The micro Vickers hardness of three different sintering temperatures were found around 2.17 – 2.236 GPa.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1417-1421
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Milling Time Parameter on the Microstructure and the Thermoelectric Properties of n-Type Bi2Te2.7Se0.3 Alloys
Autorzy:
Sharief, P.
Madavali, B.
Koo, J. M.
Kim, H. J.
Hong, S.
Hong, S.-J.
Powiązania:
https://bibliotekanauki.pl/articles/354418.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ball milling
milling time
microstructure
thermoelectric properties
ZT
Opis:
Nanostructured thermoelectric materials receiving great attention for its high thermoelectric performance. In this research, nanostructured n-type Bi2 Te2.7 Se0.3 alloys have prepared using high energy ball milling and followed by spark plasma sintering. Also, we have varied ball milling time to investigate milling time parameter on the thermoelectric properties of n-type Bi2 Te2.7 Se0.3 powder. The powders were discrete at 10 min milling and later particles tend to agglomerate at higher milling time due to cold welding. The bulk fracture surface display multi-scale grains where small grains intersperse in between large grains. The maximum Seebeck coefficient value was obtained at 20-min milling time due to their lower carrier density. The κ values were decreased with increasing milling time due to the decreasing trend observed in their κL values. The highest ZT of 0.7 at 350 K was observed for 30-min milling time which was ascribed to its lower thermal conductivity. The Vickers hardness values also greatly improved due to their fine microstructure.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 585-590
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hardness and Microstructure of Mixed Al-CNF Powder Extrusion
Autorzy:
Kim, D.-H.
Kim, T.-J.
Lim, S.-G.
Powiązania:
https://bibliotekanauki.pl/articles/351170.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-CNF composite
cold isotatic
presses
powder extrusion
LED
microstructure
Opis:
In this study, mechanical properties and microstructures of extruded aluminum matrix composites were investigated. The composite materials were manufactured by two step methods: powder metallurgy (mixture of aluminum powder and carbon fiber using a turbular mixer, pressing of mixed aluminum powder and carbon fiber using a cold isostatic pressing) and hot extrusion of pressed aluminum powder and carbon fiber. For the mixing of Al powder and carbon fibers, aluminum powder was used as a powder with an average particle size of 30 micrometer and the addition of the carbon fibers was 50% of volume. In order to make mixing easier, it was mixed under an optimal condition of turbular mixer with a rotational speed of 60 rpm and time of 1800s. The process of the hot-extrusion was heated at 450°C for 1 hour. Then, it was hot-extruded with a condition of extrusion ratio of 19 and ram speed of 2 mm/s. The microstructural analysis of extruded aluminum matrix composites bars and semi-solid casted alloys were carried out with the optical microscope, scanning electron microscope and X-ray diffraction. Its mechanical properties were evaluated by Vickers hardness and tensile test.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1267-1270
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Heat Treatment on the Microstructure and Tensile Deformation Behavior of Oxide Dispersion Strengthened Alloys Manufactured by Complex Milling Process
Autorzy:
Kim, Y.-K.
Kim, J.-H.
Gwon, J.-H.
Lee, K.-A.
Powiązania:
https://bibliotekanauki.pl/articles/352535.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ball milling
oxide dispersion strengthening
microstructure
tensile deformation behavior
Opis:
This study attempted to manufacture an ODS alloy by combining multiple milling processes in mechanical alloying stage to achieve high strength and fracture elongation. The complex milling process of this study conducted planetary ball milling, cryogenic ball milling and drum ball milling in sequential order, and then the microstructure and tensile deformation behavior were investigated after additional heat treatment. The oxide particles distributed within the microstructure were fine oxide particles of 5~20 nm and coarse oxide particles of 100~200 nm, and the oxide particles were confirmed to be composed of Cr, Ti, Y and O. Results of tensile tests at room temperature measured yield strength, tensile strength and elongation as 1320 MPa, 2245 MPa and 4.2%, respectively, before heat treatment, and 1161 MPa, 2020 MPa and 5.5% after heat treatment. This results indicate that the ODS alloy of this study gained very high strengths compared to other known ODS alloys, allowing greater plastic zones.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1335-1340
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of High-Strength Gray Cast Iron Using Permanent Magnet Scrap
Autorzy:
Park, S.-Y.
Kim, J. H.
Seo, S. J.
On, J. S.
Lim, K. M.
Powiązania:
https://bibliotekanauki.pl/articles/352204.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gray cast iron
rare earth element
Nd-Fe-B magnet scrap
graphite formation
microstructure
Opis:
In this study, we have developed the manufacturing technology for high strength gray cast irons by using the spent permanent magnet scraps. The cast specimen inoculated by using a spent magnet scraps showed the excellent tensile strength up to 306MPa. This tensile strength value is 50MPa higher than that of the specimen cast without inoculation, and is similar to that of the specimen inoculated by using the expensive misch-metal. These superior mechanical properties are attributed to complex sulfides created during solidification that promote the formation and growth of Type-A graphite. It is therefore concluded that spent magnets scrap can provide an efficient and cost-effective inoculation agent for the fabrication of high-performance gray cast iron.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1113-1117
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Trace Elements (Co, Cr) on the Microstructure and Physical Properties of Al-Si-Cu-Mg-Fe Extruded Alloy
Autorzy:
Ahn, S. S.
Sharief, P.
Lee, C. H.
Son, H. T.
Kim, Y. H.
Kim, Y. C.
Hong, S.
Hong, S. J.
Powiązania:
https://bibliotekanauki.pl/articles/352787.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-Si alloy
microstructure
extrusion
coefficient of thermal expansion
trace elements
Opis:
Trace elements Co, Cr were added to investigate their influence on the microstructure and physical properties of Al-Si extruded alloy. The Co, Cr elements were randomly distributed in the matrix, forms intermetallic phase and their existence wereconfirmed by XRD, EDS and SEM analysis. With addition of trace elements, the microstructure was modified, Si particle size was reduced and the growth rate of β-(Al5 FeSi) phase limited. Compared to parent alloy, hardness and tensile strength were enhanced while the linear coefficient of thermal expansion (CTE) was significantly reduced by 42.4% and 16.05% with Co and Cr addition respectively. It is considered that the low CTE occurs with addition of Co was due to the formation of intermetallic compound having low coefficient of thermal expansion. The results suggested that Co acts as an effective element in improving the mechanical properties of Al-Si alloy.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 857-862
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Mechanical Properties of Hot-deformed AlMg4 Alloys with the Variations of Mn, Fe, and Si Contents
Autorzy:
Lee, Da B.
Kim, Bong H.
Choi, Kweon H.
Yang, Seung Y.
Kim, Nam S.
Ha, Seong H.
Yoon, Young O.
Lim, Hyun K.
Kim, Shae
Hyun, Soong K..
Powiązania:
https://bibliotekanauki.pl/articles/351603.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-Mg alloy
intermetallic compounds
homogenization
hot-rolling
microstructure
Opis:
This paper aims to investigate the microstructural evolution and mechanical properties of hot-deformed AlMg4 alloys with Mn, Fe, and Si as the main impurities. For this purpose, solidification behavior and microstructural evolution during hot-rolling and heat-treatment processes are investigated by using theoretical calculations and experimental characterization. The crystallization and morphological transformation of intermetallic Al3 Fe, Al6 Mn, and Mg2 Si phases are revealed and discussed in terms of the variation in chemical composition. Following a homogenization heat-treatment, the effect of heat treatment on the intermetallic compounds is also investigated after hot-rolling. It was revealed that the Mg2 Si phase can be broken into small particles and spherodized more easily than the Al3 Fe intermetallic phase during the hot-rolling process. For the Mn containing alloys, both yield and ultimate tensile strength of the hot-rolled alloys increased from 270 to 296 MPa while elongation decreased from 17 to 13%, which can be attributed to Mn-containing intermetallic as well as dispersoid.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1255-1259
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process
Autorzy:
Lee, K.-A.
Kim, Y.-K.
Yu, J.-H.
Park, S.-H.
Kim, M.-C.
Powiązania:
https://bibliotekanauki.pl/articles/354570.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
selective laser melting
Ti-6Al-4V
microstructure
impact toughness
heat treatment
Opis:
This study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs) on microstructure and impact toughness of the material. Initial microstructural observation identified prior-β grain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment, α and β phase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1341-1346
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure Evolution of Ni-Based ODS Superalloy Powders During Horizontal Rotary Ball Milling
Autorzy:
Lee, H.-E.
Kim, Y. S.
Park, J. K.
Oh, S.-T.
Powiązania:
https://bibliotekanauki.pl/articles/355552.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high energy ball milling
Ni-base ODS superalloy
particle and crystalline size
microstructure
Opis:
Microstructure evolution of Ni-based oxide dispersion-strengthened alloy powders with milling time is investigated. The elemental powders having a nominal composition of Ni-15Cr-4.5Al-4W-2.5Ti-2Mo-2Ta-0.15Zr-1.1Y2O3 in wt % were ball-milled by using horizontal rotary ball milling with the change of milling velocity. Microstructure observation revealed that large aggregates were formed in the early stages of ball milling, and further milling to 5 h decreased particle size. The average crystalline size, estimated by the peak broadening of XRD, decreased from 28 nm to 15 nm with increasing milling time from 1 h to 5 h. SEM and EPMA analysis showed that the main elements of Ni and Cr were homogeneously distributed inside the powders after ball milling of 5 h.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1253-1255
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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