scholarly journals Thermal Stability of Titanium Alloy VT8M-1 with Ultrafine-Grained Structure

2020 ◽  
Vol 321 ◽  
pp. 11026
Author(s):  
A.G. Stotskiy ◽  
A.V. Polyakov ◽  
G.S. Dyakonov ◽  
I.P. Semenova
Keyword(s):  
Thermal Stability ◽  
Coarse Grained ◽  
Structural Elements ◽  
Electronic Microscopy ◽  
Rotary Swaging ◽  
Long Duration ◽  
Ultrafine Grained ◽  
Equiaxed Grains ◽  
Thermal Stability Of

The paper considers the effect of a long-duration heating at a service temperature of 450oC on VT8M-1 with a coarse-grained (CG) and ultrafine-grained (UFG) microstructure. A duplex ultrafine-grained microstructure, composed of equiaxed grains of primary α-phase and an ultrafine constituent of α- and β-phases, was processed by thermal treatment and further rotary swaging. This type of a microstructure demonstrates a best combination of strength and ductility at room temperature in comparison with the CG structure. A thermal stability of an UFG state was studied at 450°C for 50, 100, 200, 300, 400, and 500 hours. The evolution of the alloy microstructure against the duration of heating was considered by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM). No increase in the alloy structural elements and strength decrease resulting from a long-term annealing (up to 500 hours) at T=450°C have been observed. This proves a high thermal stability of the UFG structure and mechanical properties of VT8M-1 processed via rotary swaging.

The Effect of Long-Term Heating on Thermal Stability of Ultra-Fine Grained Titanium Alloy VT8M-1 Processed by Rotary Swaging

2021 ◽  
Vol 1016 ◽  
pp. 1398-1403
Author(s):  
Andrey Stotskiy ◽  
Tatyana Vitalyevna Yakovleva ◽  
Grigory Dyakonov ◽  
Alexander V. Polyakov ◽  
Irina Semenova
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Ti Alloy ◽  
Fine Grained ◽  
Rotary Swaging ◽  
Ultrafine Grained ◽  
High Level ◽  
Thermal Stability Of

The paper focuses on the analysis of microstructure and mechanical properties of the Ti alloy VT8М-1 (Ti-5.3Al-4.0Mo-1.2Zr-1.3Sn-0.2Si) in an ultrafine-grained (UFG) state subjected to a long-term annealing at a service temperature of (≤ 450°С). A rotary swaging (RS) was used to process an UFG state in the material. The precipitation of disperse silicides of S2 was observed after the deformation by RS. It has been shown that the UFG alloy retained its high level of thermal stability and enhanced mechanical properties after long-term annealing up to 500 hours. The role of disperse silicides in both strengthening and stability of mechanical properties in the alloy after long-term annealing is discussed.

Enhanced Thermal Stability and Mechanical Properties of Ultrafine-Grained Aluminum Alloy

2010 ◽  
Vol 667-669 ◽  
pp. 331-336 ◽  
Author(s):  
Rinat K. Islamgaliev ◽  
Marina A. Nikitina ◽  
Aidar F. Kamalov
Keyword(s):  
Thermal Stability ◽  
Aluminum Alloy ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
Dynamic Precipitation ◽  
Ultrafine Grained ◽  
The Mean ◽  
Fatigue Endurance ◽  
Thermal Stability Of

The paper reports on microstructure, strength and fatigue of ultrafine-grained (UFG) samples of the Al-Cu-Mg-Si aluminum alloy processed by high pressure torsion (HPT) at various temperatures. Application of the HPT treatment led to strong grain refinement, as well as to a raise of the mean-root square strains and dynamic precipitation. In case of optimal HPT treatment the UFG samples have demonstrated the enhanced thermal stability, an increase in ultimate tensile strength in 2.5 times and enhancement in fatigue endurance limit by 20 % in comparison with coarse-grained alloy subjected to standard treatment. It is shown that the regime of the HPT treatment governs the volume fraction of precipitates and segregations, thereby affecting a grain size and thermal stability of ultrafine-grained structure.

scholarly journals Co‐Evaporated MAPbI 3 : Excellent Intrinsic Long‐Term Thermal Stability of Co‐Evaporated MAPbI 3 Solar Cells at 85 °C (Adv. Funct. Mater. 22/2021)

2021 ◽  
Vol 31 (22) ◽  
pp. 2170155
Author(s):  
Herlina Arianita Dewi ◽  
Jia Li ◽  
Hao Wang ◽  
Bhumika Chaudhary ◽  
Nripan Mathews ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Solar Cells ◽  
Thermal Stability Of

Model-free kinetics applied to evaluate the long-term thermal stability of three [NTf2] anion-based ionic liquids

2017 ◽  
Vol 656 ◽  
pp. 70-84 ◽  
Author(s):  
D. Blanco ◽  
P. Oulego ◽  
D. Ramos ◽  
B. Fernández ◽  
J.M. Cuetos
Keyword(s):  
Thermal Stability ◽  
Ionic Liquids ◽  
Model Free ◽  
Model Free Kinetics ◽  
Thermal Stability Of

scholarly journals Changes in thermal stability of lignocelluloses waste aggregates long-term incorporated in composite

2021 ◽  
Vol 900 (1) ◽  
pp. 012042
Author(s):  
N Stevulova ◽  
A Estokova
Keyword(s):  
Thermal Stability ◽  
Alkaline Treatment ◽  
Cement Matrix ◽  
Scanning Calorimetry ◽  
Alkali Ions ◽  
Thermal Gravimetry ◽  
Pre Treatment ◽  
Surface Modified ◽  
Thermal Stability Of

Abstract This paper is addressed to comparative study of changes in thermal stability of surface-modified hemp-hurds aggregates long-term incorporated in bio-aggregate-based composites with the original ones before their integration into alternative binder matrix. In this study, the effectiveness of alkaline treatment of hemp hurds compared to the raw bio-aggregates as well as in relation to their behaviour when they are long-term incorporated in the MgO-cement environment is investigated. The differences in the thermal behaviour of the samples are explained by the changed structure of hemp hurds constituents due to the pre-treatment and long-term action of the alternative binder components on the bio-aggregates. Alkaline treatment increases thermal stability of hemp hurds compared to raw sample. Also long-term incorporation of hemp hurds in MgO-cement matrix had a similar effect in case of alkaline modified bio-aggregates. The more alkali ions present in the structure of hemp hurdssamples, the more ash is formed during their thermal decomposition studied by thermal gravimetry (TG) and differential scanning calorimetry (DSC).

Investigation of the Role of Intermetallic Phases in Microstructure of UFG Titanium VT8M-1 Alloy

2021 ◽  
Vol 1016 ◽  
pp. 1659-1663
Author(s):  
Tatyana Vitalyevna Yakovleva ◽  
Grigory Dyakonov ◽  
Andrey Stotskiy ◽  
Iuliia Mikhailovna Modina ◽  
Irina Semenova
Keyword(s):  
Intermetallic Phases ◽  
High Temperature Strength ◽  
Electronic Microscopy ◽  
Two Phase ◽  
Rotary Swaging ◽  
Operation Temperature ◽  
Ultrafine Grained ◽  
Alloy Microstructure ◽  
Scanning Electron

The paper studies the microstructure of two-phase ultrafine-grained titanium VT8M-1 alloy (Ti-5.7Al-3.8Mo-1.2Zr-1.3Sn), which was obtained by rotary swaging (RS). Parameters of the microstructure and the change of the phase elemental / chemical composition were investigated by scanning electron microscopy and transmission electronic microscopy. It was shown that the silicide particles like S2 - (Ti,Zr)6Si3 were precipitated in the process of rotary swaging. The influence of silicide precipitations on the characteristics of high temperature strength of the ultrafine-grained two-phase titanium VT8M-1 alloy was discussed in the paper. The alloy microstructure was analyzed after the creep-rupture tests in the operation temperature range 300-400oС.

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

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