A Study on the Aging Behavior of Al-Li-Cu-Zr Alloy

2007 ◽  
Vol 345-346 ◽  
pp. 1525-1528
Author(s):  
Tae Won Park ◽  
Young Bum Song
Keyword(s):  
Aging Time ◽  
Aging Temperature ◽  
Heat Evolution ◽  
Heat Absorption ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Δ Phase ◽  
Thermal Stability Of ◽  
Zr Alloy

Aging behavior of Al-2.1Li-2.9Cu-0.12Zr(wt%) alloy has been studied as functions of aging time and temperature by using a differential scanning calorimetry(DSC) and transmission electron microscopy(TEM). The aged specimens at 130, 160, 190°Cwere compared with the as-quenched specimen in view of the aging behavior by observing the reaction enthalpy during the heating period of DSC experiments. DSC peak associated with the formation of GP zone is not observed at 130 and 160°C, but it does at 190°C, so it is found that the thermal stability of GP zone is changed at between 160 and 190°C. At the aging temperature of 130°C, the heat absorption corresponds to the formation of δ´ increases, while the heat evolution related with the formation of T1 reveals an opposite trend. In aging temperature of 160 and 190°C, aging time representing the drastic decrease of heat absorption of δ´ is coincident with the transition time showing the decreasing of heat evolution of T1. The micro-Vickers hardness of the specimens aged at 160°C and 190°C shows maximum values about 182 and 165 at aging times of about 72 hr and 25hr, respectively. From comparing reaction enthalpies for the dissolution of δ´ and the formation of T1 phases with the aging time showing the maximum hardness, it is found that δ´ phase rather than T1 phase markedly contributes to the hardening at an aging temperature of 160°C. In contrast, T1 phase plays an important role in hardening at an aging temperature of 190°C.

Identification of Precipitates Appearing in Al-Li-Cu-Zr Alloy

2007 ◽  
Vol 124-126 ◽  
pp. 1457-1460
Author(s):  
Tae Won Park
Keyword(s):  
Heat Evolution ◽  
Hexagonal Structure ◽  
Absorption Peak ◽  
Heat Absorption ◽  
Heating Period ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Transmission Electron ◽  
Δ Phase ◽  
Zr Alloy

Identification of precipitates appearing during DSC scan of Al-2.1Li-2.9Cu-0.12Zr(wt. pct) alloy has been conducted as a function of temperature by using a differential scanning calorimetry (DSC) and transmission electron microscopy(TEM). In the as-quenched specimen from 540°C, three couples of heat evolution and absorption peaks are observed during the heating period of DSC experiments. It is found from TEM works that these peaks are associated with the formation and dissolution of GP zone, δ‘, and T1(+θ') phases. The heat evolution peak appearing in the temperature range over 36~78°C is due to the formation of GP zone. Heat absorption peak appearing in 78~140°C is associated with the dissolution of GP zone. Heat evolution peaking at 166°C in the temperature range over 140~190°C and next heat absorption peak are attributed to the formation and dissolution of δ‘ phase. Heat evolution peaking at 288°C in the temperature range of 254~332°C and heat absorption at high temperature are attributed to the formation and dissolution of T1(+θ'). The hump in DSC curve at the temperature of 425°C is considered as the formation of hexagonal structure T2 phase.

Preparation, characterization, and properties of polystyrene/Na-montmorillonite composites

2018 ◽  
Vol 32 (8) ◽  
pp. 1078-1091 ◽  
Author(s):  
Sibel Erol Dağ ◽  
Pınar Acar Bozkurt ◽  
Fatma Eroğlu ◽  
Meltem Çelik
Keyword(s):  
Electron Microscopy ◽  
Interlayer Spacing ◽  
Decomposition Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Specific Pore Volume ◽  
Transmission Electron ◽  
Thermal Stability Of

A series of polystyrene (PS)/unmodified Na-montmorillonite (Na-MMT) composites were prepared via in situ radical polymerization. The prepared composites were characterized using various techniques. The presence of various functional groups in the unmodified Na-MMT and PS/unmodified Na-MMT composite was confirmed by Fourier transform infrared spectroscopy. Morphology and particle size of prepared composites was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the XRD and TEM results, the interlayer spacing of MMT layers was expanded. SEM images showed a spongy and porous-shaped morphology of composites. TEM revealed the Na-MMT intercalated in PS matrix. The thermal stability of PS/unmodified Na-MMT composites was significantly improved as compared to PS, which is confirmed using thermogravimetric analysis (TGA). The TGA curves indicated that the decomposition temperature of composites is higher at 24–51°C depending on the composition of the mixture than that of pure PS. The differential scanning calorimetry (DSC) results showed that the glass transition temperature of composites was higher as compared to PS. The moisture retention, water uptake, Brunauer–Emmett–Teller specific surface area, and specific pore volume of composites were also investigated. Water resistance of the composites can be greatly improved.

Structure and Optical Properties of ZnO and ZnO2 Nanoparticles

2019 ◽  
Vol 56 ◽  
pp. 49-62 ◽  
Author(s):  
Javier Eliel Morales-Mendoza ◽  
Francisco Paraguay-Delgado ◽  
J.A. Duarte Moller ◽  
Guillermo Herrera-Pérez ◽  
Nicolaza Pariona
Keyword(s):  
Heat Treatment ◽  
Band Edge Emission ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Colloidal Method ◽  
Zinc Peroxide ◽  
Average Size ◽  
Thermal Stability Of ◽  
Raman And Ir Spectroscopy

Zinc oxide (ZnO) and Zinc peroxide (ZnO2) nanoparticles were synthesized by colloidal method at low temperature. The thermal stability of ZnO2was studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-Ray diffraction (XRD). The crystalline structure and phase change from ZnO2to ZnO by heat treatment was studied in detail. Morphology and particle size was examined using Transmission Electron Microscopy (TEM), for as synthesized ZnO and ZnO2the shape of particles were cuasi-spherical for both materials with average size of 10±2.2 nm and 2.5±0.4 nm, respectively; The crystal size for ZnO obtained by heat treatment was 8±2.2 nm. Electron density contours show the chemical bond type ionic and covalent for ZnO and ZnO2. The vibrational properties were analyzed by Raman and IR spectroscopy. Band gap values were obtained from ultraviolet-visible (UV-Vis) absorbance spectrum. Photoluminescence (PL) spectrum for ZnO shows two emission edges located at 445 and 492 nm and in the case of ZnO2presents one edge at 364 nm originated from the band edge emission. The optical spectra present a hypsochromic shift, compared with some reported in the literature.

TEM and DSC Studies on the Synthetic Diamond Grown from Fe-Ni-C-B System under HPHT

2011 ◽  
Vol 320 ◽  
pp. 3-7
Author(s):  
Jian Hong Gong ◽  
Shu Xia Lin ◽  
Jun Gao
Keyword(s):  
Thermal Stability ◽  
Boron Content ◽  
Synthetic Diamond ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Diamond Crystals ◽  
Transmission Electron ◽  
High Pressure High Temperature ◽  
Alloy Catalysts ◽  
Thermal Stability Of

Transmission Electron Microscope (TEM) and Different Scanning Calorimetry (DSC) Methods Were Used to Investigate the Diamonds Grown with Different Boron Content Alloy Catalysts under High-Pressure High-Temperature (HPHT). Experimental Results Demonstrated the Microstructure and Composition of Boride Compounds in Synthetic Diamond, such as (FeNi)23(CB)6 ,(Fe, Ni)3(C,B), (Fe,Ni)B and B4C, Whose Formation Process Was Analyzed. the Thermal Stability of Diamond Depends on Boron Concentration in Catalyst According to DSC Studies. we Analyzed the Reason of Diamond Oxidation.The Work Offers Valuable Information for Improving the Thermal Stability of Synthetic Diamond Crystals by Adjusting Boron Content in the Fe-Ni Based Catalyst.

scholarly journals Effects of Cold Rolling and Aging Treatment on the Properties of Cu-Be Alloy

2019 ◽  
Vol 9 (4) ◽  
pp. 4500-4503
Author(s):  
M. I. Mohamed
Keyword(s):  
Cold Rolling ◽  
Aging Time ◽  
Aging Treatment ◽  
Exothermic Peak ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Cold Rolling Reduction ◽  
Cold Rolled ◽  
Precipitated Phases ◽  
Dsc Curves

The effects of precipitated phases during aging treatment on the properties of the Cu-Be alloy have been extensively studied. In this study, the effect of cold rolling on the precipitated phases of the Cu-Be alloy compared with non-deformed alloy during isothermal and low heating rate aging of 20C/min have been investigated. Hardness changes, differential scanning calorimetry (DSC), dilatation analysis, and transmission electron microscopy (TEM) were used in this study. Hardening and contraction were strongly increased at an early aging time for the cold rolled Cu-Be alloy. In addition, the DSC curves revealed an exothermic peak from the γ΄΄ phase. This peak increased and shifted to lower aging time by increasing the cold rolling reduction. In addition, the hardness remarkably increased at lower aging temperatures for the cold rolled specimens. The contraction from the dilatation curves and the exothermic peaks shifted to lower aging temperatures in cold rolled specimens. The hardening of Cu-Be alloy is believed to be from the γ΄ phase, and the contraction and the first exothermic peak in DSC curves from γ΄΄ phase. TEM observations are in a good agreement with the above explanation and strongly revealed that γ΄΄ and γ΄ phases were highly accelerated by the effect of cold rolling

scholarly journals Effect of a Trace Addition of Sn on the Aging Behavior of Al–Mg–Si Alloy with a Different Mg/Si Ratio

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 913 ◽  
Author(s):  
Lehang Ma ◽  
Jianguo Tang ◽  
Wenbin Tu ◽  
Lingying Ye ◽  
Haichun Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Number Density ◽  
Precipitation Behavior ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Positive Effect ◽  
Room Temperature Tensile Test

In this paper, the effect of trace Sn on the precipitation behavior and mechanical properties of Al–Mg–Si alloys with different Mg/Si ratios aged at 180 °C was investigated using hardness measurements, a room-temperature tensile test, transmission electron microscopy and differential scanning calorimetry. The results shown that Sn reduces the precipitation activation energy, increases the number density of β″ precipitates, and then increased the aging hardenability and mechanical properties of the Al–Mg–Si alloy. However, the positive effect of Sn on the mechanical properties of the Al–Mg–Si alloy drops with the decrease of the Mg/Si ratio of the alloy.

scholarly journals On Long-Term Stability of Metallic Glasses

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1076 ◽  
Author(s):  
Louzguine-Luzgin ◽  
Jiang
Keyword(s):  
Metallic Glasses ◽  
Surface Oxidation ◽  
Initial Structure ◽  
Ambient Conditions ◽  
Scanning Calorimetry ◽  
Long Term Stability ◽  
Transmission Electron ◽  
Different Types ◽  
Thermal Stability Of

Thermal stability of different types of metallic glasses and partially crystalline alloys stored for at least 15 years at ambient conditions was tested in the present work by differential scanning calorimetry in comparison with that of the original alloys tested in the as-cast state in the earlier works. The structure of the naturally aged alloys was also studied by X-ray diffractometry. The structure of a couple of selected alloys was also tested by transmission electron microscopy. Most of the alloys retained their initial structure and showed only a moderate decrease in the crystallization temperature. Only those alloys which showed visible surface oxidation (Cu-Zr-system based) were partly transformed into a crystalline state forming micron-scale Cu particles in air at ambient conditions.

Preparation and characterization of poly(ethylene 2,5-furandicarboxylate/nanocrystalline cellulose composites via solvent casting

2017 ◽  
Vol 37 (9) ◽  
pp. 869-878 ◽  
Author(s):  
Amandine Codou ◽  
Nathanaël Guigo ◽  
Jesper Gabriël van Berkel ◽  
Ed de Jong ◽  
Nicolas Sbirrazzuoli
Keyword(s):  
Electron Microscopy ◽  
Crystallization Temperature ◽  
Nanocrystalline Cellulose ◽  
Solvent Casting ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Cellulose Composites ◽  
Poly Ethylene ◽  
Thermal Stability Of

AbstractThe effect of nanocrystalline cellulose dispersion on the nonisothermal crystallization of poly(ethylene 2,5-furandicarboxylate) (PEF) has been investigated by means of solvent casting. The cellulose dispersion plays a significant role on the crystallization temperature, thus dispersive equipments of increasing energies were employed to improve the cellulose particles disaggregation. Therefore, ultra-sonic bath, ultra-sonication, and ultra-turrax were used to disperse cellulose nanocrystals in 1,1,1,3,3,3-hexafluoro-2-propanol. Dissolved separately in the same solvent, PEF was then poured into the cellulose suspension before casting. The cellulose whiskers were inspected by transmission electron microscopy. Differential scanning calorimetry was used to measure the crystallization temperature, while scanning electron microscopy visualized the cellulose dispersion at the fracture surface. After investigation on the interaction of cellulose/PEF via Fourier transform infrared spectroscopy, the thermal stability of the blends was measured by means of thermogravimetric analysis.

Investigation on Aging Behavior of AZ91D Magnesium Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 1386-1389
Author(s):  
Guan Jun Liu ◽  
Wen Fang Li ◽  
Ji Hua Peng
Keyword(s):  
Magnesium Alloy ◽  
Hardness Measurement ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Az91d Magnesium Alloy ◽  
Solution Treated ◽  
Transmission Electron ◽  
Result Show ◽  
Hardening Curve ◽  
Aging Hardening

The aging hardening curve of AZ91D magnesium alloy was gained, and aging behavior of the alloy was investigated with Vickers hardness measurement, differential scanning calorimetry (DSC), transmission electron microscope (TEM) after solution treated at 415°C for 10h , and water quenched at room temperature , afterwards aged at 175°C for 0-38h with a 2h interval. The result show that there are three aging peaks at aging hardening curve of AZ91D magnesium alloy, and that four types of β-Mg17Al12 precipitates were responsible for the aging peaks.

scholarly journals High-Density Polyethylene Composites Filled with Nanosilica Containing Immobilized Nanosilver or Nanocopper: Thermal, Mechanical, and Bactericidal Properties and Morphology and Interphase Characterization

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Regina Jeziórska ◽  
Maria Zielecka ◽  
Beata Gutarowska ◽  
Zofia Żakowska
Keyword(s):  
High Density Polyethylene ◽  
Interfacial Adhesion ◽  
Crystallization Behavior ◽  
High Density ◽  
Melt Blending ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Bactericidal Properties ◽  
Excellent Activity ◽  
Thermal Stability Of

Silica containing immobilized nanosilver (Ag-SiO2) or nanocopper (Cu-SiO2) was used as a filler for high-density polyethylene (HDPE). The HDPE/Ag-SiO2and HDPE/Cu-SiO2composites were prepared by melt blending and injection molding. The microstructure of the composites was examined using transmission electron microscopy (TEM). The crystallization behavior and thermal properties were studied using differential scanning calorimetry (DSC) and thermogravimetry (TGA). The mechanical properties were characterized by tensile, flexural, and impact tests as well as dynamic mechanical thermal analysis (DMTA). The ability of silica to give antimicrobial activity to HDPE was also investigated and discussed. The TEM images indicate that Ag-SiO2show lower degree of agglomeration than Cu-SiO2nanoparticles. The crystallization temperature increased, whereas crystallinity decreased in the composites. The thermal stability of the composites was significantly better compared to HDPE. Improved stiffness indicating very good interfacial adhesion was observed. Excellent activity against different kinds of bacteria was found.

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