scholarly journals The Effect of Cobalt on the Deformation Behaviour of a Porous TiNi-Based Alloy Obtained by Sintering

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7584
Author(s):  
Nadezhda Artyukhova ◽  
Sergey Anikeev ◽  
Vladimir Promakhov ◽  
Maxim Korobenkov
Keyword(s):  
Deformation Behaviour ◽  
Structural Phase ◽  
Physical And Mechanical Properties ◽  
Physical Nature ◽  
Entire Area ◽  
Structural Phase State ◽  
Concentration Dependency ◽  
The Matrix ◽  
Research Findings ◽  
First Time

This research investigates the effect of cobalt on the deformation behaviour of a porous TiNi-based alloy that was obtained by sintering. Porous TiNi-based alloys with cobalt additives, accounting for 0–2 at. % and with a pitch of 0.5, were obtained. The structural-phase state of the porous material was researched by X-ray structural analysis. The effect of different amounts of Co (used as an alloying additive) on the deformation behaviour was investigated by tensile to fracture. The fractograms of fracture of the experimental samples were analysed using scanning electron microscopy. For the first time, the present research shows a diagram of the deformation of a porous TiNi-based alloy that was obtained by sintering under tensile. The stages of deformation were described according to the physical nature of the processes taking place. The effect of the cobalt-alloying additive on the change in the critical stress of martensitic shear was investigated. It was found that the behaviour of the concentration dependency of stress at concentrations under 1.5 at. % Co was determined by an increase in the stress in the TiNi solid solution. This phenomenon is attributed to the arrangement of Co atoms on the Ti sublattice, as well as an increase in the fraction of the B19′ phase in the matrix. The steep rise of the developed forces on the concentration dependency of the martensitic shear stress at 2 at. % Co is presumably attributed to the precipitation hardening of austenite due to the precipitation of finely dispersed coherent Ti3Ni4 phase following the decrease of fraction of martensite. An analysis of fractograms showed that as more cobalt was added, areas of fracture with traces of martensite plates of the B19′ phase started to prevail. At 2 at. % Co these plates fill almost the entire area of the fracture. The research findings presented in this work are of great importance, since they can be used to achieve the set of physical and mechanical properties required for the development of biocompatible materials for implantology.

Influence of Nanoscale Morphology on the Micro- and Macromechanical Behaviour of Polymers and Polymer Nanocomposites

2007 ◽  
Vol 121-123 ◽  
pp. 1391-1394
Author(s):  
V. Altstädt ◽  
J.K.W. Sandler ◽  
H. Ruckdäschel
Keyword(s):  
Polymer Blends ◽  
Polymer Nanocomposites ◽  
Large Scale ◽  
Mechanical Performance ◽  
Deformation Behaviour ◽  
Physical And Mechanical Properties ◽  
Crack Growth Behaviour ◽  
Novel Materials ◽  
The Matrix ◽  
Filler Particles

There is enormous scientific and economic interest in the development and evaluation of polymer nanocomposites due to the fact that the properties of a material become increasingly insensitive to flaws at the nanoscale, enabling the exploitation of the unique physical and mechanical properties of very small objects in large-scale components. However, the successful industrial implementation of such novel materials poses unique challenges which are not only related to the small size of the reinforcements. Decades of intensive research have shown that polymer nanocomposites differ from their counterparts based on traditional reinforcements in many ways and a fundamental understanding of the structure-propertyrelationships of such novel materials is only slowly emerging. Although issues such as the intrinsic properties of the nanoscale constituent as well as the degree of dispersion and orientation of individual filler particles clearly appear to be important factors, molecular interactions between the filler and the matrix during processing can lead to pronounced variations in the matrix microstructure. These variations in themselves lead to pronounced changes in the micro- and macromechanical deformation behaviour of the nanocomposites. A detailed investigation of fatigue crack growth behaviour of such novel materials for example is essential in order to understand the fracture mechanical performance and the transition from a ductile to a brittle behaviour which is often observed experimentally, especially in the case of amorphous matrices. However, as the size of the filler particles approaches the molecular level, the novel interactions at the interface or even in the interphase can lead to significant changes in the micromechanical deformation behaviour. Significant work has been carried out regarding the fracture mechanical investigation of polymer blends with both micro- and nanoscale morphologies and much can be learned by comparing the results of polymer nanocomposites to these more established polymer blends.

Influence of composition on the structural-phase state, electrophysical and magnetotransport properties of alloy thin films based on Co and Cu

Vacuum ◽  
2021 ◽  
Vol 187 ◽  
pp. 110141
Author(s):  
I.O. Shpetnyi ◽  
I.Yu Protsenko ◽  
S.I. Vorobiov ◽  
V.I. Grebinaha ◽  
L. Satrapinskyy ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase State ◽  
Structural Phase ◽  
Structural Phase State

Optimization of thermal conductivity in composites loaded with the solid-solid phase-change materials

2018 ◽  
Vol 25 (6) ◽  
pp. 1157-1165
Author(s):  
Taoufik Mnasri ◽  
Adel Abbessi ◽  
Rached Ben Younes ◽  
Atef Mazioud
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Spherical Inclusions ◽  
First Case ◽  
The Matrix ◽  
Composite Conductivity ◽  
First Time

AbstractThis work focuses on identifying the thermal conductivity of composites loaded with phase-change materials (PCMs). Three configurations are studied: (1) the PCMs are divided into identical spherical inclusions arranged in one plane, (2) the PCMs are inserted into the matrix as a plate on the level of the same plane of arrangement, and (3) the PCMs are divided into identical spherical inclusions arranged periodically in the whole matrix. The percentage PCM/matrix is fixed for all cases. A comparison among the various situations is made for the first time, thus providing a new idea on how to insert PCMs into composite matrices. The results show that the composite conductivity is the most important consideration in the first case, precisely when the arrangement plane is parallel with the flux and diagonal to the entry face. In the present work, we are interested in exploring the solid-solid PCMs. The PCM polyurethane and a wood matrix are particularly studied.

Effect of pouring temperature on A356-TiB2 MMCs cast in sand and permanent moulds by in-situ method

2016 ◽  
Vol 25 (5-6) ◽  
pp. 165-169
Author(s):  
C. Rajaravi ◽  
P.R. Lakshminarayanan
Keyword(s):  
Evaluation Studies ◽  
Physical And Mechanical Properties ◽  
Xrd Analysis ◽  
Matrix Composites ◽  
Structure Property ◽  
Pouring Temperature ◽  
Matrix Metal ◽  
Property Evaluation ◽  
The Matrix

AbstractThe paper describes a different condition of pouring temperature by sand and permanent mould to produce A356-6 wt% TiB2 metal matrix composites by in-situ method salt metal reaction route. The observation of SEM micrographs shows particle distribution of the TiB2 and it appears in hexagonal shape in Al matrix. The results of X-ray diffraction (XRD) analysis confirmed the formation of those TiB2 particulates and the results showed TiB2 particles are homogeneously dispersed throughout the matrix metal. Subsequent structure-property evaluation studies indicated sub-micron size reinforcement of in-situ formed TiB2 particles with improved physical and mechanical properties as compared to sand and permanent mould of Al-TiB2 composites. From, the permanent mould Al-TiB2 composite has an advantage of increase the properties over sand mould Al-TiB2 composite.

Influence of ball milling duration on the morphology, features of the structural-phase state and microhardness of 3Ni-Al powder mixture

2021 ◽  
Author(s):  
Ivan A. Ditenberg ◽  
Denis A. Osipov ◽  
Michail A. Korchagin ◽  
Ivan V. Smirnov ◽  
Konstantin V. Grinyaev ◽  
...  
Keyword(s):  
Ball Milling ◽  
Powder Mixture ◽  
Phase State ◽  
Structural Phase ◽  
Structural Phase State ◽  
Milling Duration ◽  
Al Powder

scholarly journals LMI-Based Stability Criterion of Impulsive T-S Fuzzy Dynamic Equations via Fixed Point Theory

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Ruofeng Rao ◽  
Zhilin Pu
Keyword(s):  
Fixed Point ◽  
Stability Criterion ◽  
High Efficiency ◽  
Fixed Point Theory ◽  
Point Theory ◽  
Linear Matrix ◽  
The Matrix ◽  
Matrix Exponential Function ◽  
Takagi Sugeno ◽  
First Time

By formulating a contraction mapping and the matrix exponential function, the authors apply linear matrix inequality (LMI) technique to investigate and obtain the LMI-based stability criterion of a class of time-delay Takagi-Sugeno (T-S) fuzzy differential equations. To the best of our knowledge, it is the first time to obtain the LMI-based stability criterion derived by a fixed point theory. It is worth mentioning that LMI methods have high efficiency and other advantages in largescale engineering calculations. And the feasibility of LMI-based stability criterion can efficiently be computed and confirmed by computer Matlab LMI toolbox. At the end of this paper, a numerical example is presented to illustrate the effectiveness of the proposed methods.

Using population-based routinely collected data from the Sentinel Stroke National Audit Programme to investigate factors associated with discharge to care home after rehabilitation

2017 ◽  
Vol 32 (8) ◽  
pp. 1108-1118 ◽  
Author(s):  
Dipankar Dutta ◽  
Daniel Thornton ◽  
Emily Bowen
Keyword(s):  
Care Home ◽  
Univariate Analysis ◽  
Population Based ◽  
National Institutes Of Health ◽  
National Audit ◽  
Factors Associated ◽  
Routinely Collected Data ◽  
Early Supported Discharge ◽  
Research Findings ◽  
First Time

Objectives: We investigated factors associated with Care Home (CH) discharge following stroke using routinely collected data in unselected patients and assessed the relevance of previous research findings to such patients seen in routine clinical practice. Design: Retrospective analysis of data from the Sentinel Stroke National Audit Programme using univariate analysis and logistic regression. Setting: A large acute and rehabilitation UK stroke unit with access to early supported discharge. Subjects: All patients with stroke treated from 1 January 2014 to 1 January 2017. Main measures: National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS). Results: Of 2584 patients (median age 78 years, interquartile range (IQR) 69–86; 50.6% male; 86.7% infarcts; median admission NIHSS 4, IQR 2–9), 401 (15.5%) died in hospital and 203 patients (7.9%) were permanently discharged to CH for the first time. Most had pre-discharge mRS scores of 4/5. Factors (odds ratios; 95% confidence intervals) associated with CH discharge included age (1.07; 1.05–1.10), incontinence (11.5; 7.13–19.25), dysphagia (2.13; 1.39–3.29), severe weakness (1.93; 1.28–2.92), pneumonia (1.68; 1.13–2.50), urinary tract infection (UTI) (1.70; 1.04–2.75) and depression (1.65; 1.00–2.72). In a subgroup of all patients with a pre-discharge mRS of 4/5, age (1.04; 1.02–1.06), incontinence (4.87; 2.39–11.02), UTI (2.0; 1.09–3.71) and pneumonia (1.59; 1.02–2.50) were the only factors associated with CH discharge. Conclusion: Potentially modifiable variables like incontinence, UTI and pneumonia were associated with CH discharge, particularly in the severely disabled.

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