scholarly journals Regularities of Structure Formation in 30 mm Rods of Thermoelectric Material during Hot Extrusion

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7059
Author(s):  
Mikhail G. Lavrentev ◽  
Vladimir T. Bublik ◽  
Filipp O. Milovich ◽  
Viktoriya P. Panchenko ◽  
Yuri N. Parkhomenko ◽  
...  
Keyword(s):  
Thermoelectric Material ◽  
Figure Of Merit ◽  
Hot Extrusion ◽  
X Ray Diffraction ◽  
Extrusion Rate ◽  
Fine Grained ◽  
Axial Texture ◽  
Fine Grained Structure ◽  
P Type ◽  
Homogeneous Strain

In this study, Ingots of (Bi, Sb)2Te3 thermoelectric material with p-type conductivity have been obtained by hot extrusion. The main regularities of hot extrusion of 30 mm rods have been analyzed with the aid of a mathematical simulation on the basis of the joint use of elastic-plastic body approximations. The phase composition, texture and microstructure of the (Bi, Sb)2Te3 solid solutions have been studied using X-ray diffraction and scanning electron microscopy. The thermoelectric properties have been studied using the Harman method. We show that extrusion through a 30 mm diameter die produces a homogeneous strain. The extruded specimens exhibit a fine-grained structure and a clear axial texture in which the cleavage planes are parallel to the extrusion axis. The quantity of defects in the grains of the (Bi, Sb)2Te3 thermoelectric material decreases with an increase in the extrusion rate. An increase in the extrusion temperature leads to a decrease in the Seebeck coefficient and an increase in the electrical conductivity. The specimens extruded at 450 °C and a 0.5 mm/min extrusion rate have the highest thermoelectric figure of merit (Z = 3.2 × 10−3 K−1).

A Study on Nanocrystalline Nickel Parts Prepared by Jet Electrodeposition

2010 ◽  
Vol 37-38 ◽  
pp. 64-67
Author(s):  
Jin Song Chen ◽  
Yin Hui Huang ◽  
Bin Qiao ◽  
Jian Ming Yang ◽  
Yi Qiang He
Keyword(s):  
Dimensional Accuracy ◽  
Processing Parameters ◽  
X Ray Diffraction ◽  
Scanning Microscope ◽  
Nanocrystalline Nickel ◽  
X Ray ◽  
Fine Grained ◽  
Average Grain Size ◽  
Jet Electrodeposition ◽  
Fine Grained Structure

The principles of jet electrodeposition orientated by rapid prototyping were introduced. The nanocrystalline nickel parts with simple shape were fabricated using jet electrodeposition. The microstructure and phase transformation of nanocrystalline nickel were observed under the scanning microscope and X-ray diffraction instrument. The results show that the jet electrodeposition can greatly enhance the limited current density, fine crystalline particles and improve deposition quality. The nickel parts prepared by jet electrodeposition own a fine-grained structure (average grain size 25.6nm) with a smooth surface and high dimensional accuracy under the optimum processing parameters.

Structure, Texture and Mechanical Properties through the Section of the Hot-Extruded Tube of Titanium Alloy PT-1M

2020 ◽  
Vol 989 ◽  
pp. 139-144 ◽  
Author(s):  
F.V. Vodolazskiy ◽  
N.A. Barannikova ◽  
Anatoly G. Illarionov
Keyword(s):  
Titanium Alloy ◽  
Extrusion Direction ◽  
Hot Extrusion ◽  
Tangential Direction ◽  
Primary Recrystallization ◽  
Recrystallization Temperature ◽  
Fine Grained ◽  
Surface Areas ◽  
Α Phase ◽  
Fine Grained Structure

The study considers the formation of the structure, texture, and hardness of hot extruded tube of titanium alloy PT-1M. It is shown that hot extrusion at 840 °C, which is higher than the α-phase recrystallization temperature, results to the development of dynamic and primary recrystallization processes and ensures the formation of homogeneous and fine-grained structure through-out the cross section with a two-component tangential texture (0001)TD<100>ED+(0001)TD<110>ED (TD – tangential direction, ED – extrusion direction) and hardness of 155 HV. It has been established that a higher cooling rate of the surface areas of the tube after extrusion results to a less active development of recrystallization processes, which lead to the formation of a finer granular structure near the outer surface. This weakens recrystallization component of (0001)TD<110>ED, compared to other areas of the tube.

scholarly journals STRUCTURE AND PROPERTIES OF AZ31 MAGNESIUM ALLOY AFTER COMBINATION OF HOT EXTRUSION AND ECAP

2017 ◽  
Vol 23 (3) ◽  
pp. 222 ◽  
Author(s):  
Ondřej Hilšer ◽  
Stanislav Rusz ◽  
Wojciech Maziarz ◽  
Jan Dutkiewicz ◽  
Tomasz Tański ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Hot Extrusion ◽  
Az31 Magnesium Alloy ◽  
Initial State ◽  
Fine Grained ◽  
Angular Pressing ◽  
Ecap Process ◽  
Average Grain Size ◽  
Fine Grained Structure

<p>Equal channel angular pressing (ECAP) method was used for achieving very fine-grained structure and increased mechanical properties of AZ31 magnesium alloy. The experiments were focused on the, in the initial state, hot extruded alloy. ECAP process was realized at the temperature 250°C and following route Bc. It was found that combination of hot extrusion and ECAP leads to producing of material with significantly fine-grained structure and improves mechanical properties. Alloy structure after the fourth pass of ECAP tool with helix matrix 30° shows a fine-grained structure with average grain size of 2 µm to 3 µm and high disorientation between the grains. More experimental results are discussed in this article.</p>

scholarly journals Effect of Radial Forging on the Microstructure and Mechanical Properties of Ti-Based Alloys

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1488
Author(s):  
Lev B. Zuev ◽  
Galina V. Shlyakhova ◽  
Svetlana A. Barannikova
Keyword(s):  
Phase State ◽  
Metal Flow ◽  
Mechanical Processing ◽  
Radial Forging ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Fine Grained ◽  
Fine Grained Structure

Radial forging is a reliable way to produce Ti alloy rods without preliminary mechanical processing of their surface, which is in turn a mandatory procedure during almost each stage of the existing technology. In the present research, hot pressing and radial forging (RF) of the titanium-based Ti-3.3Al-5Mo-5V alloy were carried out to study the specifics of plasticized metal flow and microstructural evolution in different sections of the rods. The structural analysis of these rods was performed using metallography and X-ray diffraction techniques. The X-ray diffraction reveals the two-phase state of the alloy. The phase content in the alloy was shown to vary upon radial forging. Finally, radial forging was found to be a reliable method to achieve the uniform fine-grained structure and high quality of the rod surface.

The Structure and Shape Memory of the Hot Extruded NiTi Alloy

2016 ◽  
Vol 687 ◽  
pp. 19-24
Author(s):  
Tomasz Goryczka ◽  
Zdzisław Lekston ◽  
Jerzy Dybich ◽  
Maciej Zubko ◽  
Tadeusz Wierzchoń ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Cast Alloy ◽  
Niti Alloy ◽  
Hot Extrusion ◽  
Point Of View ◽  
Niti Shape Memory Alloy ◽  
X Ray Diffraction ◽  
Axial Texture ◽  
Texture Type

The paper presents results of structural studies of hot extruded NiTi shape memory alloy that is in the B2 phase at room temperature. Texture of the alloy was determined from the X-ray diffraction measurements. It was found that in result of 60 % sample reduction (at a cross-section of a bar formed by hot extrusion) weak axial texture - type <110>B2 was formed. The volume of the grains oriented in this way was approx. 20 %. Basing on metallographic observations it was also found that the size of the grains formed as a result of the thermomechanical treatment was uniform with the average area of 1700 μm2. This information is significant from the point of view of functional properties. Hot extruded alloy revealed presence of the reversible martensitic transformation. Its characteristic temperatures were slight higher than in as-cast alloy. Moreover, the extruded NiTi alloy showed 100 % of the shape recovery.

Thermoelectric properties of germanium telluride with fine-grained structure

2020 ◽  
Vol 11 ◽  
pp. 15-25
Author(s):  
L. D. Ivanova ◽  
◽  
Yu. V. Granatkina ◽  
I. Yu. Nikhezina ◽  
A. G. Malchev ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Melt Spinning ◽  
High Energy ◽  
Grain Structure ◽  
Thermoelectric Efficiency ◽  
Fine Grained ◽  
Germanium Telluride ◽  
Fine Grained Structure ◽  
Properties Of Materials ◽  
P Type

The microstructure and thermoelectric properties of materials based on germanium telluride p-type conductivity doped with copper and bismuth obtained by hot pressing of three types powders prepared by grinding an ingot to a size of hundreds microns (0.315  mm) to hundreds of nanometers (mechanical activation) in planetary high-energy mill and melt spinning were investigated. The microstructure of the samples were analyzed by optical and electron scanning microscopies. The nanoscale grain structure of these samples was established. The thermoelectric characteristics of the materials: Seebeck coefficient, electrical and thermal conductivities, were measured both at room temperature and in the temperature range of 100 – 800 K. The slopes of these dependencies are estimated. The coefficient of thermoelectric figure of merit is calculated. The higher thermoelectric efficiency (ZT = 1.5 at 600 K) was received for the samples hot-pressed from granules, prepared by melt spinning.

Improving power factor and figure of merit of p-type CuSbSe2 via introducing Sb vacancies

2021 ◽  
Author(s):  
Tao Chen ◽  
Hongwei Ming ◽  
Xiaoying Qin ◽  
Chen Zhu ◽  
Lulu Huang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Material ◽  
Power Factor ◽  
Figure Of Merit ◽  
Environment Friendly ◽  
Low Thermal Conductivity ◽  
P Type

As a thermoelectric material, p-type CuSbSe2 has attracted much attention due to its intrinsic low thermal conductivity and environment-friendly constituents. In this work, Sb deficient compounds CuSb1-xSe2 (x=0-0.12) are prepared...

The Application of Nano-Structured Silica Based Admixture in Gypsum Binders

2014 ◽  
Vol 1611 ◽  
pp. 165-170 ◽  
Author(s):  
E.V. Voitovich ◽  
A.V. Cherevatova ◽  
I.V. Zhernovsky ◽  
H.-B. Fisher ◽  
K. Sobolev
Keyword(s):  
Quartz Sand ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Experimental Program ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
Size And Morphology ◽  
Nanostructured Silica

ABSTRACTThis article reports on a new composite gypsum binder (CGB) with nanostructured silica-based admixture (NSS). NSS is obtained by a wet ultrafine milling of quartz sand resulting in the formation of an inorganic polydisperse binding system, which has a high concentration of active nanoscale phase (about 10%). Developed CGB contains hemihydrate gypsum and nano-component based on quartz sand. It is observed that the addition of 15–20 % of NSS improves the rheological properties of gypsum systems through the formation of solvate shells hindering the access of water to gypsum particles; this process also retards the setting of binder.The experimental program used infrared IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) to reveal the contribution of NSS. The porosity of CGB is analyzed by the kinetics of water adsorption and BET. The XRD and IR investigations determined the formation of a new sulfosilicate phase, hydroxyellestadite during the hydration of CGB. With the addition of NSS an overall reduction in pore volume, as well as the shifts in macro-, meso- and nano- porosity values are observed.Analysis of CGB microstructure reveals that in the presence of the NSS the size and morphology of crystals are changed contributing to the formation of dense fine-grained structure. Experimental studies have demonstrated that the composite gypsum binders with NSS are characterized by reduced water absorption and increased density, as well as improved mechanical performance especially, higher compressive strength.

Microstructure and Performance of Nanocrystalline Nickel Parts

2011 ◽  
Vol 287-290 ◽  
pp. 420-423
Author(s):  
Jin Song Chen
Keyword(s):  
Dimensional Accuracy ◽  
Processing Parameters ◽  
X Ray Diffraction ◽  
Nanocrystalline Nickel ◽  
Fine Grained ◽  
Rapid Fabrication ◽  
Jet Electrodeposition ◽  
Fine Grained Structure ◽  
And Performance ◽  
Microstructure And Performance

Jet electrodeposition orientated by rapid fabrication were introduced , The nanocrystalline nickel parts were fabricated using jet electrodeposition . The microstructure and phase transformation of nanocrystalline nickel were observed under the scanning microscope and X-ray diffraction instrument . The results show that the jet electrodeposition can greatly enhance the limited current density, fine crystalline particles and improve deposition quality. The nickel parts prepared by jet electrodeposition own a fine-grained structure with a smooth surface and high dimensional accuracy under the optimum processing parameters.

scholarly journals Investigation of Thermal Properties of Half-Heusler Alloy FeVZ (Z= As, P, Sb) within Density Functioal Theory

2021 ◽  
Vol 4 (1) ◽  
pp. 45-51
Author(s):  
Anugrah Azhar
Keyword(s):  
Density Functional Theory ◽  
Thermal Properties ◽  
Thermoelectric Material ◽  
Temperature Regime ◽  
Heusler Alloy ◽  
Potential Application ◽  
Figure Of Merit ◽  
Density Functional ◽  
Functional Theory ◽  
P Type

The figure of merit (ZT) holds an important role in thermoelectric material that indicates the efficiency of thermoelectric (TE) devices. The higher ZT value, the higher efficiency would be obtained of TE devices. One of the sub-class materials that has high potential application for thermoelectric material is half-Heusler (HH) alloy. In order to investigate the ZT value of HH conduct simulation using to investigate the ZT value of HH alloy FeVZ (Z= As, P, Sb) by using density-functional theory (DFT). Our research results show that FeVAs has higher ZT values than FeVP and FeVSb in the range temperature of 150-900 K. All of those compounds still have good ZT value around ~0.7 even in the temperature regime of 900 K, and shows a good trend for p-type thermoelectric materials.

Sign in / Sign up

Export Citation Format

Share Document