scholarly journals Анизотропия термического расширения поликристаллического сплава системы Ni-Mn-Ga, подвергнутого пластической деформации ковкой

2018 ◽  
Vol 60 (6) ◽  
pp. 1051
Author(s):  
И.И. Мусабиров ◽  
И.М. Сафаров ◽  
Р.М. Галеев ◽  
Р.А. Гайсин ◽  
В.В. Коледов ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Bimodal Distribution ◽  
Structural Studies ◽  
Alloy Structure ◽  
Isothermal Forging ◽  
Bimodal Structure ◽  
Grain Sizes ◽  
Geometric Size ◽  
The Stability

AbstractThe formation of a sharp crystallographic texture in a Ni–Mn–Ga Heusler alloy by the multiple isothermal forging has been studied. An analysis of the thermal expansion near the martensitic transformation temperatures in the as-cast and forged states of the alloy shows that the thermomechanical treatment leads to an increase in the anisotropy of the sample geometric size changing during the phase transformation, which favors an increase in the functional characteristics of the alloy. The structural studies show that the alloy structure after multiple isothermal forging has the bimodal distribution of grain sizes. The formation of the bimodal structure by forging is assumed to make it possible to enhance the stability of the functional properties of the alloy during repeated cycles of the phase transformation.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

Transformation behavior of yttria stabilized tetragonal zirconia polycrystal–TiB2 composites

2001 ◽  
Vol 16 (7) ◽  
pp. 2158-2169 ◽  
Author(s):  
B. Basu ◽  
J. Vleugels ◽  
O. Van Der Biest
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Mechanical Analysis ◽  
Transformation Behavior ◽  
Thermal Expansion Data ◽  
Thermally Induced ◽  
First Time ◽  
Tetragonal Zirconia Polycrystal

The objective of the present article is to study the influence of TiB2 addition on the transformation behavior of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). A range of TZP(Y)–TiB2 composites with different zirconia starting powder grades and TiB2 phase contents (up to 50 vol%) were processed by the hot-pressing route. Thermal expansion data, as obtained by thermo-mechanical analysis were used to assess the ZrO2 phase transformation in the composites. The thermal expansion hysteresis of the transformable ceramics provides information concerning the transformation behavior in the temperature range of the martensitic transformation and the low-temperature degradation. Furthermore, the transformation behavior and susceptibility to low-temperature degradation during thermal cycling were characterized in terms of the overall amount and distribution of the yttria stabilizer, zirconia grain size, possible dissolution of TiB2 phase, and the amount of residual stress generated in the Y-TZP matrix due to the addition of titanium diboride particles. For the first time, it is demonstrated in the present work that the thermally induced phase transformation of tetragonal zirconia in the Y-TZP composites can be controlled by the intentional addition of the monoclinic zirconia particles into the 3Y-TZP matrix.

Microstructural development of ZnO using a rate-controlled sintering dilatometer

1996 ◽  
Vol 11 (3) ◽  
pp. 671-679 ◽  
Author(s):  
Gaurav Agarwal ◽  
Robert F. Speyer ◽  
Wesley S. Hackenberger
Keyword(s):  
Thermal Expansion ◽  
Heating Rate ◽  
Grain Growth ◽  
Microstructural Development ◽  
Constant Heating Rate ◽  
Temperature Determination ◽  
Grain Sizes ◽  
Rate Controlled ◽  
Temperature Controlled ◽  
Constant Heating

Rate-controlled sintering (RCS) of isostatically pressed particulate compacts of ZnO showed lower average grain sizes and intragranular pore densities than constant heating rate temperature controlled sintering. Valid comparisons of this form could only be made after corrections to hardware and software which reduced specimen creep under dilatometer pushrod load, nonuniform pushrod expansion, reproducible specimen temperature determination, thermal expansion during sintering, and instantaneous termination of sintering at the specified end of RCS. The improved microstructures from RCS were attributed to maximized efficiency of densification, optimizing the time and temperatures permitted for grain growth.

scholarly journals Real-time observation of the thermally-induced phase transformation in GeTe and its thermal expansion properties

2019 ◽  
Vol 165 ◽  
pp. 327-335 ◽  
Author(s):  
Xuan Quy Tran ◽  
Min Hong ◽  
Hiroshi Maeno ◽  
Youichirou Kawami ◽  
Takaaki Toriyama ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Real Time ◽  
Thermally Induced ◽  
Time Observation ◽  
Real Time Observation

scholarly journals Phase Transformation of Cr(VI)-Adsorbed Ferrihydrite at Different pH in The Presence of Mn(II): Fate of Mn(II) and Cr(VI)

2021 ◽  
Author(s):  
Zecong Ding ◽  
Fenglian Fu ◽  
Guangzhao Sun ◽  
Chujia Ye
Keyword(s):  
Phase Transformation ◽  
Heavy Metal Ions ◽  
Solid Phase ◽  
Transformation Products ◽  
Transformation Process ◽  
Toxic Heavy Metal ◽  
Chromium Vi ◽  
Initial Ph ◽  
The Stability ◽  
Mn Concentration

Abstract Ferrihydrite is an important sink for the toxic heavy metal ions, such as chromium(VI). As ferrihydrite is thermodynamically unstable and gradually transforms into hematite and goethite, the stability of Cr(VI)-adsorbed ferrihydrite is environmentally significant. This study investigated the phase transformation of Cr(VI)-adsorbed ferrihydrite at different pH in the presence of aqueous Mn(II), as well as the fate of Mn(II) and Cr(VI) in the transformation process of ferrihydrite. Among the ferrihydrite transformation products, hematite was dominant, and goethite was minor. The pre-adsorbed Cr(VI) inhibited the conversion of ferrihydrite to goethite at initial pH 3.0, whereas little amount of adsorbed Mn(II) favored the formation of goethite at initial pH 7.0. After the aging process, Cr species in solid phase existed primarily as Cr(III) in the presence of Mn(II) at initial pH 7.0 and 11.0. The aqueous Mn concentration was predominantly unchanged at initial pH 3.0, whereas the aqueous Mn(II) was adsorbed onto ferrihydrite or form Mn(OH)2 precipitates at initial pH 7.0 and 11.0, promoting the immobilization of Cr(VI). Moreover, the oxidation of Mn(II) occurred at initial pH 7.0 and 11.0, forming Mn(III/IV) (hydr)oxides.

scholarly journals The effect of thermal expansion on diffusion flame instabilities

2010 ◽  
Vol 647 ◽  
pp. 453-472 ◽  
Author(s):  
M. MATALON ◽  
P. METZENER
Keyword(s):  
Thermal Expansion ◽  
Diffusion Flame ◽  
Initial Mixture ◽  
Surprising Result ◽  
Flame Instability ◽  
Preferential Diffusion ◽  
The Stability ◽  
Flame Instabilities ◽  
Comprehensive Characterization

In this paper we examine the effect of thermal expansion on the stability of a planar unstrained diffusion flame and provide a comprehensive characterization of diffusive-thermal instabilities while realistically accounting for density variations. The possible patterns that are likely to be observed as a result of differential and preferential diffusion are identified for a whole range of parameters including the distinct Lewis numbers associated with the fuel and oxidizer, the initial mixture strength and the flow conditions. Although we find that thermal expansion has a marked influence on flame instability, it does not play a crucial role as it does in premixed combustion. It primarily affects the parameter regime associated with the onset of the instabilities and the growth rate of the unstable modes. Perhaps the most surprising result is that its has a different influence on the various modes of instability – a destabilizing influence on the formation of cellular structures and a stabilizing influence on the onset of oscillations.

Phase Transformation and Thermal Expansion of Zirconium and Hafnium Titanates and Their Solid Solutions

1988 ◽  
Vol 71 (2) ◽  
pp. 120-127 ◽  
Author(s):  
HIROYUKI IKAWA ◽  
AKIHITO IWAI ◽  
KAZUYUKI HIRUTA ◽  
HIROMASA SHIMOJIMA ◽  
KAZUYORI URABE ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Solid Solutions

scholarly journals Use of liners made of concrete on quartz aggregates and polyurethane composition to reduce vibration, noise and improve the stability of tramway track

2018 ◽  
Vol 230 ◽  
pp. 03014 ◽  
Author(s):  
Olena Palant ◽  
Dmytro Plugin ◽  
Andrii Plugin ◽  
Alexey Lobiak ◽  
Oleksii Pluhin
Keyword(s):  
Thermal Expansion ◽  
Structural Characteristics ◽  
Linear Thermal Expansion ◽  
The Finite Element Method ◽  
Temperature Stresses ◽  
The Stability ◽  
Water Saturated ◽  
Quartz Aggregates ◽  
Optimal Strength ◽  
Polyurethane Composition

The theoretical basis of reduction of thermal deformations of the ballastless continuous welded track has been developed. The design of the track with integrated rails has been improved by using a special concrete liner of optimal composition with quartz fillers and aggregates and two-component polyurethane. The method of calculating the concrete composition with optimal strength and coefficient of linear thermal expansion together with optimal structural characteristics, To reduce the temperature stresses in the rails, liners should be made of concrete with quartz fillers and aggregates which provide a reduction of the coefficient of linear thermal expansion αL to 1.1×10-6 K-1. The analysis of the stressstrain state of the rails during heating, performed using the finite element method, has shown that the liners made of concrete with quartz aggregates decrease by 10-32% the temperature stresses in rails. The composition of concrete for liners with the compressive strength of above 60 MPa has been substantiated and the polyurethane composition has been selected for insulation of rails from the channel wall with adhesion to concrete of 0.7 MPa in a dry state, 0.43 MPa in a water-saturated state, and adhesion to steel of 1.2 MPa.

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