scholarly journals Thermoelastic Properties and Elastocaloric Effect in Rapidly Quenched Ribbons of Ti2NiCu Alloy in the Amorphous and Crystalline State

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 949
Author(s):  
Evgeny Morozov ◽  
Dmitry Kuznetsov ◽  
Vladimir Kalashnikov ◽  
Koledov Victor ◽  
Vladimir Shavrov
Keyword(s):  
Mechanical Stress ◽  
Coefficient Of Thermal Expansion ◽  
Relative Elongation ◽  
Landau Theory ◽  
Amorphous State ◽  
External Action ◽  
Elastic Behavior ◽  
Specific Power ◽  
Thermoelastic Properties ◽  
Elastocaloric Effect

The thermoelastic properties and the elastocaloric effect (ECE) were studied in rapidly quenched ribbons of the Ti2NiCu alloy samples in amorphous and crystalline states under periodic mechanical tension with a frequency of up to 50 Hz. In the amorphous samples, elastic behavior is observed, described by Hooke’s law, with a high coefficient of thermal expansion α = 1.7 × 10−4 K−1. Polycrystalline ribbons of the Ti2NiCu alloy have the classical shape memory effect (SME), the temperatures of the forward and reverse thermoelastic martensitic transitions being Ms = 345 K, Mf = 325 K, As = 332 K, and Af = 347 K and the coefficient of the dependence of the transition temperature on mechanical stress being β = 0.12 K/MPa. The experimentally measured value of the adiabatic temperature change under the action of mechanical stress (ECE) in the amorphous state of the alloy at room temperature (Tr = 300 K) was ΔT = −2 K, with a relative elongation of ε = 1.5% and a mechanical stress of σ = 243 MPa. For crystalline samples of Ti2NiCu alloy ribbons, the ECE is maximum near the completion temperature of the reverse thermoelastic martensitic transformation Af, and its value was 21 K and 7 K under cyclic mechanical loads of 300 and 100 MPa, respectively. It is shown that the ECE value does not depend on the frequency of external action in the range from 0 to 50 Hz. The specific power of the rapidly quenched ribbon was evaluated as a converter of thermal energy at an external mechanical stress of 100 MPa; its value was 175 W/g at a frequency of 50 Hz. The thermodynamic model based on the Landau theory of phase transitions well explains the properties of both amorphous ribbons (reverse ECE) and alloy ribbons with EPF (direct ECE).

scholarly journals Эластокалорический эффект в быстрозакаленном сплаве Ti-=SUB=-2-=/SUB=-NiCu при периодическом воздействии растягивающей силы с частотой до 50 Hz

2020 ◽  
Vol 62 (6) ◽  
pp. 864
Author(s):  
Е.В. Морозов ◽  
С.Ю. Федотов ◽  
А.В. Петров ◽  
М.С. Быбик ◽  
Т.А. Кули-заде ◽  
...  
Keyword(s):  
Phase Transition ◽  
Mechanical Stress ◽  
Specific Power ◽  
Martensitic Transition ◽  
Periodic Action ◽  
Mechanical Loads ◽  
First Order ◽  
Elastocaloric Effect ◽  
Martensitic Phase Transition ◽  
External Loads

Abstract The elastocaloric effect (ECE) is studied in samples of rapidly quenched ribbons of a Ti_2NiCu alloy at a periodic action by a mechanical stress to 300 MPa at a frequency to 50 Hz. ECE is maximal near the temperatures of a first-order thermoelastic martensitic phase transition. The ECE maximum is observed in a point corresponding to the completion of the reverse martensitic transition ( T = 67.5°C) and is 21 and 6 K at cyclic mechanical loads of 300 and 100 MPa, respectively. The ECE value is shown to be independent of the frequency of the external loads in the range from 0 to 50 Hz. The specific power of a rapidly quenched ribbon as a thermal energy transformer is estimated at the external mechanical stress of 100 MPa; its value is 150 W/g at a frequency of 50 Hz and ECE is 6 K.

Static and dynamical elastic behavior of Lu5Ir4Si10 around its first-order structural phase transition

2020 ◽  
Vol 34 (12) ◽  
pp. 2050116
Author(s):  
M. Saint-Paul ◽  
C. Opagiste ◽  
C. Guttin
Keyword(s):  
Phase Transition ◽  
Theoretical Approach ◽  
Order Parameter ◽  
Landau Theory ◽  
Structural Phase ◽  
Elastic Stiffness ◽  
Elastic Behavior ◽  
Velocity Measurements ◽  
First Order ◽  
First Order Transition

Ultrasonic velocity measurements could be performed on a good quality single crystal of [Formula: see text] around its transition around 80 K. The behavior of the stiffness components demonstrates a first-order transition. The temperature dependence of the longitudinal elastic stiffness components [Formula: see text] and [Formula: see text] can be analyzed by the classical Landau theory and assuming a stricter coupling between the strain and the order parameter. A theoretical approach and experimental results are discussed.

Study of Warpage and Mechanical Stress of 2.5D Package Interposers during Chip and Interposer Mount Process

2012 ◽  
Vol 2012 (1) ◽  
pp. 000967-000974 ◽  
Author(s):  
Takashi Hisada ◽  
Yasuharu Yamada ◽  
Junko Asai ◽  
Toyohiro Aoki
Keyword(s):  
Mechanical Stress ◽  
Dielectric Layer ◽  
Coefficient Of Thermal Expansion ◽  
Transmission Rate ◽  
Organic Substrate ◽  
Electrical Performance ◽  
Von Mises Stress ◽  
Design Elements ◽  
Plastic Ball ◽  
Low K

As data transmission rate increases, flip chip plastic ball grid array (FCPBGA) utilizing a interposer for multiple chips is gaining popularity because of high electrical performance, ease of chip design, ease of thermal management with thermal lid, etc. The authors assessed package design configuration and key design elements for two chips application assuming 1600 signal I/Os for logic and 800 signal I/Os for memory. Then, we studied warpage behavior of the interposer, and mechanical stress of solder interconnections and low-k dielectric layer under controlled collapse chip connection (C4) pad. We set three different mount process assumptions for chip to interposer and interposer to base organic substrate. The mount process assumptions are (1) two pass reflow of chip to interposer first, then interposer to base organic substrate, (2) reversed sequence of two pass reflow which is interposer to base organic substrate first, then chip to interposer, (3) one pass reflow of chip, interposer and base organic substrate all together. We also set three different interposer material assumptions of Si, glass and organic in this study. We analyzed warpage behavior and mechanical stress using finite element method (FEM) modeling technique with a set of combinations of coefficient of thermal expansion (CTE) and elastic modulus of the interposers. The study also includes an analysis for conventional multi-chip-module (MCM) FCPBGA as a reference. We show the analysis results of interposer warpage, first principal stress at low-k dielectric layer under C4 pad and von Mises stress at solder interconnections of chip joining and interposer joining.

scholarly journals DETECTION OF MECHANICAL STRESS LIMITING EFFECTS OF CRANE STRUCTURE DEFORMATION

2021 ◽  
Vol 2021 (6) ◽  
pp. 5396-5402
Author(s):  
LEOPOLD HRABOVSKY ◽  
◽  
ZDENEK FOLTA ◽  
Keyword(s):  
Mechanical Stress ◽  
Relative Elongation ◽  
Tensile Force ◽  
Steel Structure ◽  
Mechanical Tests ◽  
Construction Design ◽  
Axial Forces ◽  
Instantaneous Values ◽  
The Individual ◽  
Short Time

The paper presents a construction design and results of laboratory tests of so-called mechanical stress detectors, which can be used to detect the deformation of the steel structure of a crane and to amplify the mechanical signal from the effect of the so-called crane skewing, which is included among occasional loads acting on the crane. The values of the relative elongation of the detectors corresponding to the magnitude of the instantaneous tensile force were obtained by conducting experimental mechanical tests. Detectors of a known extent of deformation were installed on a two-girder overhead crane bridge, where they measured axial forces generated during the controlled deformation of the crane bridge. In practice, the instantaneous values of the axial forces recorded by the individual detectors make it possible to regulate the speed of the crane drive wheels and thus eliminate, in a relatively short time, the undesirable effects of deforming the crane bridge and friction of the crane wheels on the sides of the rail heads.

Mechanical Stress as a Function of Temperature in Thin Aluminum Films and its Alloys

1988 ◽  
Vol 130 ◽  
Author(s):  
Donald S. Gardner ◽  
Paul A. Flinn
Keyword(s):  
Aluminum Alloys ◽  
Thermal Cycling ◽  
Mechanical Stress ◽  
Film Stress ◽  
Solid State Reactions ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Aluminum Films ◽  
Thin Aluminum ◽  
Stress Changes

AbstractAluminum alloys have virtually replaced aluminum for interconnections in VLSI because of their improved reliability. Mechanical stress is a problem of growing importance in these interconnections. Stress as a function of temperature was measured for thin aluminum films and several aluminum alloys and layered films consisting of silicon, copper, titanium, tungsten, tantalum, vanadium, and TiSi2. Solid-state reactions of the aluminum with the additives and with the ambient during thermal cycling will occur and depending on what compounds have formed and at what temperature, this will determine the morphology and reliability of the metallization. The measurement technique, based on determination of wafer curvature with a laser scanning device, directly measures the total film stress and reflectivity in situ during thermal cycling. Changes in stress were detected when film composition and structure varied and were correlated using x-ray diffraction with the formation of aluminides. Other phenomena that contribute to stress changes including elastic behavior, recrystallization, grain growth, plastic behavior, yield strength, and film hardening from precipitates.

scholarly journals Метод определения параметров парного межатомного потенциала

2020 ◽  
Vol 62 (7) ◽  
pp. 998
Author(s):  
М.Н. Магомедов
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Interatomic Potential ◽  
Coefficient Of Thermal Expansion ◽  
State Equation ◽  
Zero Temperature ◽  
Thermoelastic Properties ◽  
Lennard Jones ◽  
Sublimation Energy ◽  
Potential Parameters

Disadvantages of methods known from the literature for determining 4 parameters of the paired interatomic potential of Mie-Lennard-Jones in relation to crystals are indicated. A new method is proposed for determining the parameters of this potential from the thermoelastic properties of the crystal. In this method the parameters are determined by the best coincidence of calculated values with experimental data: 1) of the sublimation energy of the crystal at zero temperature (T = 0 K) and pressure (P = 0); 2) of coefficient of thermal expansion and isothermal elastic modulus, which were measured at P = 0 and T = 300 K; 3) of the dependence of the isotherm T = 300 K state equation from volume of P(300 K, V). The method was tested on iron and gold and showed good results. By this method also were determined the interatomic potential parameters for refractory metals: Nb, Ta, Mo, and W. The results obtained also made it possible to determine more precisely such properties of these metals as the sublimation energy, the Debye temperature, and the surface energy.

Elastic Behavior, Birefringence, and Swelling of Amorphous Polyethylene Networks

1968 ◽  
Vol 41 (5) ◽  
pp. 1182-1193
Author(s):  
A. N. Gent ◽  
V. V. Vickroy
Keyword(s):  
Optical Anisotropy ◽  
Crystalline State ◽  
Amorphous State ◽  
Elastic Behavior ◽  
Molten State ◽  
Γ Irradiation ◽  
Linear Polyethylene ◽  
Solvent Interaction ◽  
Γ Radiation ◽  
Equilibrium Swelling

Abstract Polyethylene networks were prepared by γ-irradiation of linear polyethylene, both molten and crystalline. Elastic and. photoelastic properties of the networks were studied at high temperatures, i.e., in the molten state. Equilibrium swelling was also measured in several solvents. Values of the crosslinking efficiency G of γ-radiation, the molecular weight Me between entanglements, the optical anisotropy α of the equivalent random link, and the polymer-solvent interaction parameter μ are deduced. Samples prepared by irradiation in the amorphous state showed markedly nongaussian elastic behavior. The presence of a large nongaussian term in the optical anisotropy is also deduced. The value of α obtained for swollen samples, which showed substantially gaussian elastic behavior, was 3.9×10−24, about one half of that obtained for dry samples. It corresponds to an equivalent random link of only about 5 CH2 units, on the basis of Denbigh's values for bond polarizabilities. The samples prepared by irradiation in the crystalline state also showed lower values for α, depending on the degree of crosslinking. This is attributed to the nonrandom chain configurations prevailing at the time of crosslinking. The same samples were found to show more nearly gaussian elastic behavior, which is attributed to the same cause.

Experimental Study on the Relation between Elastic and Thermal Deformation of the AZ31 Magnesium Alloy and Composite

2011 ◽  
Vol 465 ◽  
pp. 423-426 ◽  
Author(s):  
Zdeněk Drozd ◽  
Zuzanka Trojanová ◽  
Pavel Lukáč
Keyword(s):  
Experimental Study ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Thermal Deformation ◽  
Coefficient Of Thermal Expansion ◽  
Relative Elongation ◽  
Linear Thermal Expansion ◽  
Az31 Alloy ◽  
Protective Atmosphere ◽  
Sic Nanoparticles

The dilatation characteristics of the continuosly cast AZ31 alloy and composite with AZ31 matrix reinforced by SiC nanoparticles were investigated in the temperature range of 20-410 °C. The axis of specimens was either parallel or perpendicular to the casting texture. The linear thermal expansion of the alloy as well as the composite was measured in an argon protective atmosphere using a Netzsch 410 dilatometer. The relative elongation and coefficient of thermal expansion are the main experimental results obtained using dilatometry. The temperature dependence of the elastic modulus can be calculated using analysis of the dilatometry results.

Electron Microscopy of Metal-Matrix Composites

1970 ◽  
Vol 28 ◽  
pp. 404-405
Author(s):  
A. Lawley ◽  
M. R. Pinnel ◽  
A. Pattnaik
Keyword(s):  
Electron Microscopy ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Critical Evaluation ◽  
Elastic Behavior ◽  
Matrix Composites ◽  
Directionally Solidified ◽  
Fracture Characteristics ◽  
Broad Program

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.

Role of boundaries in the crystallization of amorphous films

1988 ◽  
Vol 46 ◽  
pp. 626-627
Author(s):  
D. A. Smith
Keyword(s):  
Low Temperature ◽  
Amorphous State ◽  
Nucleation And Growth ◽  
Amorphous Films ◽  
Island Nucleation ◽  
Surface Steps ◽  
Transmission Electron ◽  
Component Systems ◽  
Temperature Deposition

The nucleation and growth processes which lead to the formation of a thin film are particularly amenable to investigation by transmission electron microscopy either in situ or subsequent to deposition. In situ studies have enabled the observation of island nucleation and growth, together with addition of atoms to surface steps. This paper is concerned with post-deposition crystallization of amorphous alloys. It will be argued that the processes occurring during low temperature deposition of one component systems are related but the evidence is mainly indirect. Amorphous films result when the deposition conditions such as low temperature or the presence of impurities (intentional or unintentional) preclude the atomic mobility necessary for crystallization. Representative examples of this behavior are CVD silicon grown below about 670°C, metalloids, such as antimony deposited at room temperature, binary alloys or compounds such as Cu-Ag or Cr O2, respectively. Elemental metals are not stable in the amorphous state.

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