A5036849407- Shape Memory Alloy Transformations
- Heusler alloys: electronic and magnetic properties
- Magnetic and transport properties of perovskites and related materials
- Magnetic Properties and Applications
- High Entropy Alloys Studies
- Advanced Welding Techniques Analysis
- Microstructure and Mechanical Properties of Steels
- High-Temperature Coating Behaviors
- Intermetallics and Advanced Alloy Properties
- Magnetic Properties of Alloys
- Piezoelectric Actuators and Control
- Recycling and utilization of industrial and municipal waste in materials production
- Advanced ceramic materials synthesis
- Metal and Thin Film Mechanics
- MXene and MAX Phase Materials
- Advanced materials and composites
- Magnetic properties of thin films
- Advanced Thermoelectric Materials and Devices
- Topological Materials and Phenomena
- Additive Manufacturing Materials and Processes
Muğla University
2014-2023
Kastamonu University
2020
University of Duisburg-Essen
2015-2019
Martensitic transitions in shape memory Ni-Mn-Ga Heusler alloys take place between a high temperature austenite and low martensite phase. However, intermartensitic transformations have also been encountered that occur from one phase to another. To examine magnetic detail, we carried out dependent magnetization, resistivity, x-ray diffraction measurements investigate the transition Ni50Mn50–xGax composition range 12≤x≤25 at. %. Rietveld refined results are found be consistent with...
Despite the importance of martensitic transformations Ni-Mn-Ga Heusler alloys for their magnetocaloric and shape-memory properties, part phase diagrams is not well determined. Using an ab initio approach that includes interplay lattice vibrational degrees freedom we identify intermartensitic transformation between a modulated nonmodulated as function excess Ni Mn content. Based on evaluation theoretical findings experimental x-ray diffraction data Mn-rich alloys, are able to predict diagram...
Exchange bias is observed in ferromagnetic/antiferromagnetic (FM/AF) layered stacks and materials with neighboring ferromagnetic antiferromagnetic granules. The latter commonly Ni-Mn-based martensitic Heusler alloys. In general, the exchange-bias effect identified as horizontally shifted hysteresis loop when system field cooled from high temperatures. We report here shifts not only under field-cooled but also zero-field-cooled conditions magnetically granular...
Abstract We report on a new functional property in an AF martensitic Heusler Ni 50 Mn 45 In 5 , which when annealed at high temperatures under magnetic field, segregates and forms 25 precipitates embedded matrix. The are paramagnetic whereas the matrix is antiferromagnetic. However, spins interface with align field during their nucleation growth become strongly pinned direction of applied annealing, core paramagnetic. This shell-ferromagnetism persists up to 600 K so that remanent...
Abstract Martensitic transformations of rapidly quenched and less‐rapidly cooled Heusler alloys type Ni–Mn–X with X=Ga, In, Sn are investigated by ab initio calculations. For from 1173 K, we obtain the well‐known magnetocaloric properties near phase transition. secondary heat treatment these start to change considerably, because each alloy transforms during temper‐annealing into a dual‐phase composite alloy. These two phases identified be cubic stoichiometric Ni 2 MnX tetragonal disordered NiMn.
The present study on magnetic and structural properties of Ni50Mn45Ga5 confirms that metastability is an inherent property Ni50Mn50–xXx Heusler alloys with X as In, Ga, Sn. ternary alloy transforms during temper-annealing into a dual-phase composite alloy. two phases are identified to be cubic L21, Ni50Mn25Ga25, tetragonal L10 Ni50Mn50. Depending the annealing temperature, magnetic-proximity effect giving rise shell-ferromagnetism has been observed when carried out under external field....
Segregation in a series of ${\mathrm{Ni}}_{2}{\mathrm{Mn}}_{1+x}{(\mathrm{In},\phantom{\rule{4pt}{0ex}}\mathrm{Sn},\phantom{\rule{4pt}{0ex}}\mathrm{Ga},\phantom{\rule{4pt}{0ex}}\mathrm{Al})}_{1\ensuremath{-}x}$ and ${\mathrm{Mn}}_{2}{\mathrm{Ni}}_{1+x}$(Ga, Al) as well ${\mathrm{Ni}}_{2+x}{\mathrm{Mn}}_{1\ensuremath{-}x}\mathrm{Ga}$ Heusler alloys is studied by first-principles calculations. We show that Mn-rich...
Shell-ferromagnetic effects are observed in Ni-Mn-based off-stoichiometric Heuslers decomposed into ferromagnetic precipitates embedded an antiferromagnetic matrix when the surface-to-volume ratio of sufficiently large. However, since size have until now not been determined, it is known which ratios involved. Here we carry out a Scherrer analysis on specimens to determine precipitate-size as function decomposition temperature and time.
Shell ferromagnetism is a new functional property of certain Heusler alloys which was recently observed in ${\mathrm{Ni}}_{50}{\mathrm{Mn}}_{45}{\mathrm{In}}_{5}$. We report the results comparative study magnetic microstructure bulk ${\mathrm{Ni}}_{50}{\mathrm{Mn}}_{45}{\mathrm{In}}_{5}$ using magnetometry, synchrotron x-ray diffraction, and small-angle neutron scattering (SANS). By combining unpolarized spin-polarized SANS (so-called POLARIS) we demonstrate that number important conclusions...
Ni–Mn–Ga Heusler alloys are particularly interesting for their magnetic shape‐memory properties. However, more recently, the observation of glass‐like behavior in these alloys, at low Ga concentrations, has extended interest properties alloys. We have investigated thermomagnetic Ni Mn alloy with . In this relatively concentration, we find kinetic arrest and exchange‐bias effects occurring concurrently. show that related to presence mixed ferromagnetic antiferromagnetic interactions two...
Abstract The properties of high-entropy alloys containing five or more elements show systematic evolutions with varying valence-electron concentration. This can allow them to be tailored carry a particular feature property. We have prepared six-component alloy (MnFeCoNiCu) $$_{75}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>75</mml:mn> </mml:msub> </mml:math> Al $$_{25}$$ <mml:mn>25</mml:mn> , where MnFeCoNiCu makes up the part $$e/a=9.0$$...
Ni2MnX-based Heusler (X: main group element), when enriched with Mn, will decompose into ferromagnetic Ni2MnX and antiferromagnetic NiMn temper-annealed around 650 K. When the starting material is chosen such that X-composition about 5 at. % annealing takes place in presence of a magnetic field 1 T, resulting composite nanoprecipitate strongly pinned shell-ferromagnets soft core embedded matrix. We show shells precipitates are so estimated required to fully reorient spins order 20 T. examine...
Martensitic transformations are strain driven displacive transitions governing the mechanical and physical properties in intermetallic materials. This is case ${\mathrm{Ni}}_{2}\mathrm{MnGa}$, where martensite transition at heart of striking magnetic shape memory magnetocaloric properties. Interestingly, martensitic transformation preceded by a premartensite phase, role this precursor its influence on still matter debate. In work we report Co doping...
The present work deals with magnetic and structural phase instabilities in Ni-Mn-based Heusler alloys especially Ni-Mn-Al. temper-annealed Ni50Mn45Al5 alloy decomposes into the full stoichiometric Ni2MnAl NiMn phases. decomposed forms precipitates an anti-ferromagnetic matrix exhibits shell-ferromagnetic properties when temper-annealing is performed under field. shell-ferromagnetism results from proximity effect observed as vertically shifted magnetization loops. presence of this property...
Invar and anti-Invar are materials having anomalously low high thermal expansion coefficients, respectively. In the case of Invar, this is related to magneto-volume fluctuations occurring between a large-volume-high-moment state an energetically higher-lying small-volume-low-moment state. For it opposite. 3d metals alloys, occurrence both effects governed by valence-electron-concentration, $e/a$. The authors provide face-lift for alloys showing that they can also be tailored as high-entropy...
The shell-ferromagnetic effect originates from the segregation process in off-stoichiometric Ni–Mn-based Heusler.
Off stoichiometric Heuslers in the form Ni50Mn50−xZx, where Z can be a group 13–15 element of periodic system, decompose at about 650 K into ferromagnetic full Heusler Ni50Mn25Z25 and an antiferromagnetic Ni50Mn50 component. We study here case for as Sb report on shell-ferromagnetic properties well thermal instabilities. Unlike other Z-elements, Ni50Mn50−xSbx, minimum decomposition temperature corresponds to lying within austenite state so that it is possible observe change martensitic...
The applicability of the magnetic shape memory effect in Ni-Mn-based martensitic Heusler alloys is closely related to nature crystallographically modulated martensite phase these materials. We study properties phases as a function temperature and composition three Ni49.8Mn25.0Ga25.2, Ni49.8Mn27.1Ga23.1 Ni49.5Mn28.6Ga21.9. substituting Ga for Mn leads an anisotropic expansion lattice, where b-parameter 5M structure increases c-parameters decrease with increasing concentration. modulation...
NiMn is a collinear antiferromagnet with high magnetocrystalline anisotropy ($K=\ensuremath{-}9.7\ifmmode\times\else\texttimes\fi{}{10}^{5}\phantom{\rule{4pt}{0ex}}\text{J}\phantom{\rule{0.16em}{0ex}}{\text{m}}^{\ensuremath{-}3}$). Through magnetic annealing of excess Ni, strongly pinned moments emerge due to an imbalance in the distribution Ni antiferromagnetic Mn sublattices. The results are explained model field biased diffusion, supported by ab initio calculations. Another observation...
Ni-Co-Mn-In Heusler-based compounds are interesting for their magnetocaloric properties and have been widely investigated this purpose. For Co compositions more than 5 at% in (${\mathrm{Ni}}_{100\ensuremath{-}x}{\mathrm{Co}}_{x}{)}_{50}{\mathrm{Mn}}_{25+y}{\mathrm{In}}_{25\ensuremath{-}y}$ the material is no longer single phase, $y<25$, shell-ferromagnetic precipitation occurs. Our study twofold: First we here of these systems show that ferromagnetic exchange can be strengthened by...