scholarly journals Principles of certification of metals for susceptibility to brittleness by the criterion of critical strength

2021 ◽  
pp. 48-54
Author(s):  
Yu.Ya. Mieshkov
Keyword(s):  
Critical Temperature ◽  
Brittle Fracture ◽  
Evaluation System ◽  
Quantitative Measure ◽  
Problem Definition ◽  
Strength Parameter ◽  
Correlation Ratio ◽  
Critical Strength ◽  
Full Scale Tests ◽  
Critical Temperature Tc

Problem definition. Existing evaluation system of liability to brittle fracture is based on specifying the critical temperature Tc of ductile/brittle transition for specimens with stress concentrator (SC) and uses relative values of impact toughness (KCV, KCU) and widening (ψк). Thus the Tc becomes relative and it is not possible to measure brittleness or embrittlement degree for specimens with SC. Paper purpose. Neutralize the system faults of evaluation system of liability to brittle fracture of constructional alloys with SC. The concept is to change the KCV (KCU) or ψк  parameters by critical strength parameter (ϭ0,2с at Tc). Conclusions. Fracture of the specimen with SC (ϭNF) on YTS (ϭ0,2с) at Tc (or room TR) as embrittlement criterion is proposed instead of relative values of (KCV, KCU) and (ψк). The ϭNF / ϭ0,2 = BrNF ratio is a degree of reliability for specimen with SC (BrNF > 1) or embrittlement measure (BrNF < 1). The BrNF value is a quantitative measure of the fracture resistivity of the specimen with SC or crack. Correlation ratio between Br and BrNF  for each type of SC has been found. It allows to use the calculation of embrittlement liability based on metal strength for test of metals without full scale tests of metal specimens with SC. Keywords: embrittlement; fracture degree; fracture resistivity; critical temperature; critical strength; strengthreliability of the specimen with SC

Pressure-induced superconducting CS2H10 with H3S framework

2021 ◽  
Author(s):  
Mingyang Du ◽  
Zihan Zhang ◽  
Tian Cui ◽  
Defang Duan
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Critical Temperature ◽  
Superconducting State ◽  
High Temperature Superconducting ◽  
Critical Temperature Tc ◽  
Important Milestone

The discovery of the high temperature superconducting state in compounds of hydrogen, carbon and sulfur with the critical temperature (Tc) of 288 K at high pressure is an important milestone...

Preparation of EuBCO Epitaxial and Textured Films by F-Free Polymer-Assisted Chemical Solution Deposition Method

2013 ◽  
Vol 745-746 ◽  
pp. 261-266 ◽  
Author(s):  
Xin Zhang ◽  
Cui Hua Cheng ◽  
Wen Tao Wang ◽  
Yong Zhang ◽  
Yong Zhao
Keyword(s):  
Critical Temperature ◽  
Chemical Solution Deposition ◽  
Temperature Treatment ◽  
Nitrogen Atmosphere ◽  
High Temperature Treatment ◽  
Single Crystal Substrate ◽  
Chemical Solution ◽  
Organic System ◽  
Solution Deposition ◽  
Critical Temperature Tc

Epitaxial and textured EuBa2Cu3O7-x(EuBCO) superconductive films were prepared via a F-free polymer-assisted chemical solution deposition (PACSD) method on LaAlO3 (LAO) single crystal substrate in nitrogen atmosphere. Because of the fluorine-free metal organic system, no harmful gas was produced during processing by the PA-CSD method. The film morphorlogy, phase composition, texture and the superconducting critical temperature (Tc) of EuBCO films were investigated by x-ray diffraction (XRD),φ-scan, ω-scan rocking curves, an environmental scanning electron microscope (ESEM) and four-probe method. The Jc value of the EuBCO film in self-field at 77K was measured by using Jc-scan Leipzig system. The results shoed that a denser microstructure and better biaxial texture EuBCO film after a high temperature treatment with a superconducting critical temperature (Tc) of 91K was obtained . The critical current density (Jc) reached 2.4MA/cm2 at 77K in the self-field.

scholarly journals Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Swagata Acharya ◽  
Dimitar Pashov ◽  
Cédric Weber ◽  
Hyowon Park ◽  
Lorenzo Sponza ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Degrees Of Freedom ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spin Fluctuations ◽  
Charge Fluctuations ◽  
Ab Initio Theory ◽  
Charge Parity ◽  
Local Correlations ◽  
Critical Temperature Tc

AbstractUnconventional superconductivity in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$Sr2RuO4 has been intensively studied for decades. However, the nature of pairing continues to be widely debated. Here we develop a detailed ab initio theory, coupling quasiparticle self-consistent GW approximation with dynamical mean field theory (DMFT), including both local and non-local correlations to address the subtle interplay among spin, charge and orbital degrees of freedom. We report that the superconducting instability has multiple triplet and singlet components. In the unstrained case the triplet eigenvalues are larger than the singlets. Under uniaxial strain, the triplet eigenvalues drop and the singlet components increase. This is concomitant with our observation of spin and charge fluctuations shifting closer to wave-vectors favoring singlet pairing. We identify a complex mechanism where charge fluctuations and spin fluctuations co-operate in the even-parity channel under strain leading to increment in critical temperature (Tc), thus proposing a novel mechanism for pushing the frontier of critical temperature (Tc) in unconventional ‘triplet’ superconductors.

Temperature Dependence of Amorphization above 10K in the CuTi Intermetallic Compound Under Electron Irradiation

1986 ◽  
Vol 74 ◽  
Author(s):  
J. Koike ◽  
D. E. Oluzzi ◽  
M. Meshii ◽  
P. R. Okamoto
Keyword(s):  
Critical Temperature ◽  
Intermetallic Compound ◽  
Cluster Formation ◽  
Irradiation Temperature ◽  
Crystalline Compound ◽  
Temperature Dependent ◽  
Defect Clusters ◽  
Critical Dose ◽  
Increasing Temperature ◽  
Critical Temperature Tc

AbstractThe critical dose required to amorphize the crystalline compound CuTi during irradiation with 1 MeV electrons has been investigated from 10 to 288 K. The results show that above a critical temperature (Tc) of about 185 K, CuTi remains crystalline and only defect clusters are formed. Below Tc, amorphization occurs with no observable cluster formation. The critical dose for amorphization was found to be temperature dependent below Tc: as the irradiation temperature increases, a higher dose is required to induce amorphization. This observation supports the concept that Tc corresponds to the vacancy migration temperature. Below Tc, interstitial migration may contribute to the observed reduction in the amorphization rate with increasing temperature.

Properties of MgB2 Fabricated by Sintering Mg and B Sandwich Structures

2008 ◽  
Vol 1099 ◽  
Author(s):  
Andrew Yeung ◽  
Dickon H. L. Ng
Keyword(s):  
Critical Temperature ◽  
Magnesium Diboride ◽  
Sandwich Structures ◽  
Argon Atmosphere ◽  
Lateral Size ◽  
Boron Powder ◽  
Different Temperatures ◽  
Average Size ◽  
Cold Pressed ◽  
Critical Temperature Tc

AbstractMagnesium diboride (MgB2) was successfully produced in a pellet with sandwich-like structure. The sample was prepared by embedding a layer of Mg powder in between layers of boron powder before they were cold-pressed and sintered in argon atmosphere at different temperatures. After sintering, the interfacial regions between the Mg and B layers were examined and hexagonal platelets were observed lying along the interfacial regions in samples sintered at temperatures above 700°C. These hexagonal platelets were confirmed as MgB2. When samples were sintered at higher temperatures, the lateral size of the platelets increased. At 700°C, the average size of the platelets was 0.5 μgm, and it increased to 1.5 μgm in sample sintered at 900°C. In addition, the critical temperature (TC) and the magnetization (M) were also changed from 35.4 K to 37.1 K and −0.7 to −1.8 emu/g, respectively.

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