A SISF formation mechanism in Ni3Al

1990 ◽  
Vol 48 (4) ◽  
pp. 472-473
Author(s):  
Dongliang Lin ◽  
Mao Hen
Keyword(s):  
Formation Mechanism ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Antiphase Boundary ◽  
Dislocation Dipole ◽  
Directionally Solidified ◽  
Superlattice Dislocation ◽  
Thin Foils ◽  
Specimen Axis ◽  
Axis Parallel

In the ordered Ll2 structure, the superlattice intrinsic stacking fault (SISF) has often been observed to be formed through two steps, the formation of antiphase boundary (APB) by dissociation of superlattice dislocation at first and then the conversion of the APB to the SISF(1,2). The present paper studied the SISF in NijAl by TEM and found that the SISF can also be formed by superlattice dislocation dipoles.The tensile deformation of the directionally solidified Ni3Al (of composition in wt% of 82.88Ni, 8.5A1, 0.8Zr, 7.8Cr, and 0.02B) specimens was performed at room temperature. Thin foils were made normal to the specimen axis (parallel to [001]) and studied at 200 kv in H-800.As shown in Fig.l, a SISF is formed at the end of a superlattice dislocation dipole, according to the SISF-type dissociation [10] =1/3 [11]+1/3[2l] on (111) plane. In Fig.2, a superlattic dislocation dipole is moving away from a SISF.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

Formation Mechanism and Chirality Evolution of Chiral Carbon Dots Prepared via Radical Assisted Synthesis at Room Temperature

Nanoscale ◽  
2021 ◽  
Author(s):  
Lorenzo Branzi ◽  
Giacomo Lucchini ◽  
Elti Cattaruzza ◽  
Nicola Pinna ◽  
Alvise Benedetti ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Formation Mechanism ◽  
Carbon Dots ◽  
Room Temperature ◽  
Chiral Carbon

We report on a Cu(II) catalyzed process for the production of cysteine based chiral carbon dots, the process does not require any thermal treatment and the carbon dots formation is...

The effect of strain rates on tensile deformation of ultrafine-grained copper

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744014
Author(s):  
M. Li ◽  
Q. W. Jiang
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Strain Rates ◽  
Roll Bonding ◽  
Fracture Elongation ◽  
Tensile Deformation Behavior ◽  
Ultrafine Grained ◽  
Flow Stress Level

Tensile deformation behavior of ultrafine-grained (UFG) copper processed by accumulative roll-bonding (ARB) was studied under different strain rates at room temperature. It was found that the UFG copper under the strain rate of 10[Formula: see text] s[Formula: see text] led to a higher strength (higher flow stress level), flow stability (higher stress hardening rate) and fracture elongation. In the fracture surface of the sample appeared a large number of cleavage steps under the strain rate of 10[Formula: see text] s[Formula: see text], indicating a typical brittle fracture mode. When the strain rate is 10[Formula: see text] or 10[Formula: see text] s[Formula: see text], a great amount of dimples with few cleavage steps were observed, showing a transition from brittle to plastic deformation with increasing strain rate.

Room temperature Mg reduction of TiO2: formation mechanism and application in photocatalysis

2019 ◽  
Vol 55 (53) ◽  
pp. 7675-7678 ◽  
Author(s):  
Di Zu ◽  
Zhongfei Xu ◽  
Ao Zhang ◽  
Haiyang Wang ◽  
Hehe Wei ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Formation Mechanism ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Oxide Structure

A Mg/HCl infiltrated metal oxide structure was designed as a facile approach for implanting oxygen vacancies and H atoms into metal oxides.

Nanostructure formation mechanism during in-situ consolidation of copper by room-temperature ball milling

2015 ◽  
Vol 65 ◽  
pp. 1083-1090 ◽  
Author(s):  
M. Samadi Khoshkhoo ◽  
S. Scudino ◽  
T. Gemming ◽  
J. Thomas ◽  
J. Freudenberger ◽  
...  
Keyword(s):  
Ball Milling ◽  
Formation Mechanism ◽  
Room Temperature ◽  
Nanostructure Formation

Uniaxial Ratchetting of Filled Rubber: Experiments and Damage-Coupled Hyper-Viscoelastic-Plastic Constitutive Model

2018 ◽  
Vol 85 (6) ◽  
Author(s):  
Yifu Chen ◽  
Guozheng Kang ◽  
Jianghong Yuan ◽  
Chao Yu
Keyword(s):  
Experimental Data ◽  
Constitutive Model ◽  
Applied Stress ◽  
Stress Level ◽  
Cyclic Deformation ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Accumulated Damage ◽  
Filled Rubber ◽  
Cyclic Tension

A series of stress-controlled uniaxial cyclic tension-unloading tests are discussed to investigate the ratchetting of a filled rubber at room temperature. It is shown that obvious ratchetting occurs and depends apparently on the applied stress level, stress rate, and stress history. Based on the experimental observations, a damage-coupled hyper-viscoelastic-plastic constitutive model is then developed to describe the ratchetting of the filled rubber, which consists of three branches in parallel, i.e., a hyperelastic, a viscoelastic, and a plastic one. The damage is assumed to act equally on three branches and consists of two parts, i.e., the Mullins-type damage caused by the initial tensile deformation and the accumulated damage occurred during the cyclic deformation. The developed model is validated by comparing the predicted results with the experimental data.

Magnetic Enhancement and Nitriding Process of Fe Atomic Layers on Si (111)-7×7-CH3OH Surface

2021 ◽  
Author(s):  
Wenxin Li ◽  
Wanyu Ding ◽  
Youping Gong ◽  
Dongying Ju
Keyword(s):  
Formation Mechanism ◽  
Room Temperature ◽  
Adsorption Process ◽  
Linear Structure ◽  
Atomic Layer ◽  
Residual Magnetization ◽  
Good Stability ◽  
Iron Nitride ◽  
Dissociation Process ◽  
Magnetic Performance

Abstract Fe atoms were steamed on Si(111)-7×7 surface, which had been saturated by CH3OH. Aim to greatly enhance the magnetic performance, nitriding experiments were implemented and adjusted on the existing linear Fe clusters. First of all, the dissociation of CH3OH adsorption process was deducted in detail, which laid a good foundation for the better use of surface quasi-potential. Further to solve the coming problems like weak linearity and low nitriding effect, the formation mechanism of iron-nitride was explored. Atomic layers of Fe deposition are confirmed as the key to NH3 dissociation process (at room temperature). Specifically, the higher Fe atomic layer contacted by NH3, the weaker influence of surface quasi-potential. With the introduction of Ar, Fe deposition could be controlled at 1-2 atomic layers, result in good NH3 dissociation and nitriding efficiency. Combing with magnetic performance result, the density of residual magnetization is improved from 1.5E-0.5 emu to 7.0E-0.5 emu, forming an obvious linear structure. It is also proved that our new linear iron-nitride clusters will maintain good stability with the improvement of nitriding efficiency.PACS: 07.79.Cz; 81.15.-z; 75.75.Fk

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