scholarly journals Crystallization Features of Amorphous Rapidly Quenched High Cu Content TiNiCu Alloys upon Severe Plastic Deformation

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2670
Author(s):  
Alexander Glezer ◽  
Nikolay Sitnikov ◽  
Roman Sundeev ◽  
Alexander Shelyakov ◽  
Irina Khabibullina
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Copper Content ◽  
Melt Spinning ◽  
High Pressure Torsion ◽  
Amorphous State ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cu Content ◽  
Rapid Melt Quenching

In recent years, the methods of severe plastic deformation and rapid melt quenching have proven to be an effective tool for the formation of the unique properties of materials. The effect of high-pressure torsion (HPT) on the structure of the amorphous alloys of the quasi-binary TiNi–TiCu system with a copper content of more than 30 at.% produced by melt spinning technique has been analyzed using the methods of scanning electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry (DSC). The structure examinations have shown that the HPT of the alloys with a Cu content ranging from 30 to 40 at.% leads to nanocrystallization from the amorphous state. An increase in the degree of deformation leads to a substantial change in the character of the crystallization reflected by the DSC curves of the alloys under study. The alloys containing less than 34 at.% Cu exhibit crystallization peak splitting, whereas the alloys containing more than 34 at.% Cu exhibit a third peak at lower temperatures. The latter effect suggests the formation of regions of possible low-temperature crystallization. It has been established that the HPT causes a significant decrease in the thermal effect of crystallization upon heating of the alloys with a high copper content relative to that of the initial amorphous melt quenched state.

scholarly journals Improved Tensile Ductility by Severe Plastic Deformation for Nano-Structured Metallic Glass

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1611 ◽  
Author(s):  
Yue Dong ◽  
Suya Liu ◽  
Johannes Biskupek ◽  
Qingping Cao ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Severe Plastic Deformation ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Homogeneous Material ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Strain Limit ◽  
Small Volume Fraction

The effect of severe plastic deformation by high-pressure torsion (HPT) on the structure and plastic tensile properties of two Zr-based bulk metallic glasses, Zr55.7Ni10Al7Cu19Co8.3 and Zr64Ni10Al7Cu19, was investigated. The compositions were chosen because, in TEM investigation, Zr55.7Ni10Al7Cu19Co8.3 exhibited nanoscale inhomogeneity, while Zr64Ni10Al7Cu19 appeared homogeneous on that length scale. The nanoscale inhomogeneity was expected to result in an increased plastic strain limit, as compared to the homogeneous material, which may be further increased by severe mechanical work. The as-cast materials exhibited 0.1% tensile plasticity for Zr64Ni10Al7Cu19 and Zr55.7Ni10Al7Cu19Co8.3. Following two rotations of HPT treatment, the tensile plastic strain was increased to 0.5% and 0.9%, respectively. Further testing was performed by X-ray diffraction and by differential scanning calorimetry. Following two rotations of HPT treatment, the initially fully amorphous Zr55.7Ni10Al7Cu19Co8.3 exhibited significantly increased free volume and a small volume fraction of nanocrystallites. A further increase in HPT rotation number did not result in an increase in plastic ductility of both alloys. Possible reasons for the different mechanical behavior of nanoscale heterogeneous Zr55.7Ni10Al7Cu19Co8.3 and homogeneous Zr64Ni10Al7Cu19 are presented.

Obtaining and Characterization of Ni-Ti Alloys Processed through Powder Metallurgy

2017 ◽  
Vol 1143 ◽  
pp. 13-19
Author(s):  
Florentina Potecaşu ◽  
Octavian Potecaşu ◽  
Francisco Manuel Braz Fernandes ◽  
Petrică Alexandru ◽  
Alexandru Alexa
Keyword(s):  
Plastic Deformation ◽  
Powder Metallurgy ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Niti Alloy ◽  
Ultrafine Grain ◽  
Mass Composition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Fine Grain

This study presents the result of the researches regarding the obtaining of NiTi alloy through powder metallurgy (PM) as a possible alternative to present technologies (melting through induction in vacuum—MIV and re-melting with electric arch in vacuum—VAR). The researches made by the authors have aim at the obtaining of Ni-Ti materials with fine grain or ultrafine grain through powder metallurgy techniques, starting from ordinary metallic powders of Ti, Ni, Cu, with grain size less than 100 micrometers, and also using processing through severe plastic deformation (HPT — high pressure torsion). The fabrication through PM has an important advantage because a product requires low processing subsequent considering that it can get with sizes and shape very similar to the final ones, which is not negligible if one takes into account that the alloys Ni-Ti do not excel on cutting processability. Cylindrical samples were produced by cold uniaxial compression, at the specific pressure of 600 MPa, dosed in a proportion of 52.5 % Ni + 43.5 % Ti + 4.0 % Cu, mass composition. The compressed samples, after the sintering in vacuum and severe plastic deformation have been characterized by X-ray diffraction (XRD) , differential scanning calorimetry (DSC) and optical microscopy.

Thermo- and Deformation Induced Martensitic Transformations in Binary TiNi-Based Alloys Subjected to Severe Plastic Deformation

2013 ◽  
Vol 738-739 ◽  
pp. 530-534 ◽  
Author(s):  
Natalia N. Kuranova ◽  
Vladimir V. Makarov ◽  
Vladimir G. Pushin ◽  
Alexey N. Uksusnikov
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Amorphous State ◽  
Cold Drawing ◽  
Martensitic Transformations ◽  
Subsequent Annealing ◽  
Structure And Phase Transformations

Results of investigations of structure and phase transformations and properties of the TiNi-based alloys with a shape memory effect (SME) after severe plastic deformation (SPD) by cold rolling, cold drawing, high pressure torsion and subsequent annealing are reported. It is found that the baroelastic effects related to the highly reversible martensitic transformations can occur in alloys, subjected to high pressure. The evolution of fine structure of the alloys into nanocrystalline and then amorphous state during SPD and after subsequent annealing have been studied. The effect of grain size on the martensitic transformations and properties of the alloys is discussed.

Phase Transformations «Amorphization ↔ Crystallization» In Metallic Materials Induced by Severe Plastic Deformation

2018 ◽  
Vol 54 (1) ◽  
pp. 93-105 ◽  
Author(s):  
R.V. Sundeev ◽  
A. M. Glezer ◽  
A. V. Shalimova
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Amorphous State ◽  
Structural Features ◽  
Nanocrystalline State ◽  
Basic Principles ◽  
Phase Cycling ◽  
Different Temperatures

Abstract In this review we are considered systematically the phenomenon of deformation-induced phase transformations from crystalline intermetallic compounds and complex phases to amorphous state and vice versa phase transformations from amorphous state to crystalline one upon severe plastic deformation at different temperatures. The nature and structural features of these transitions essentially for high pressure torsion deformation are analyzed in the frame of basic principles of nonequilibrium thermodynamics. The effects of phase cycling and a stationary amorphous - nanocrystalline state formation at significant deformations is discussed in details.

scholarly journals Особенности кристаллизации аморфных сплавов TiNiCu с высоким содержанием меди

2020 ◽  
Vol 62 (6) ◽  
pp. 829
Author(s):  
А.В. Шеляков ◽  
Н.Н. Ситников ◽  
И.А. Хабибуллина ◽  
Р.В. Сундеев ◽  
О.Н. Севрюков
Keyword(s):  
Copper Content ◽  
Amorphous State ◽  
X Ray Diffraction ◽  
Initial State ◽  
Scanning Calorimetry ◽  
Two Phase ◽  
Casting Technique ◽  
Stage Crystallization ◽  
Structure And Phase Transformations ◽  
B2 Phase

Alloys of the quasi-binary TiNi – TiCu system with a copper content of 25, 30, 35, and 40 at. % were obtained by planar flow casting technique at a cooling rate of 10^6 K/s in the form of ribbons 30–50 μm thick and 10–20 mm wide. The structure and phase transformations in the alloys were studied using electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry. It was found that in the initial state, the alloys with 25 and 30 at.% Cu have an amorphous-crystalline structure, undergoing a one-stage polymorphic crystallization of the amorphous state on heating in a calorimeter with the formation of austenite B2 phase, which on cooling to room temperature proceeds to orthorhombic B19 phase due to the martensitic transformation. It is shown that the alloys with 35 and 40 at.% Cu at quenching become amorphous, and upon heating, two-stage crystallization occurs (primary and eutectic) with the formation of a two-phase structure - the tetragonal B11 (TiCu) phase with a small fraction of B2 phase. Moreover, an increase in the copper content leads to a decrease in the onset temperature of crystallization.

scholarly journals Applications of Differential Scanning Calorimetry on Materials Subjected by Severe Plastic Deformation

2008 ◽  
Vol 584-586 ◽  
pp. 255-260 ◽  
Author(s):  
Nong Gao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Solid State Reactions ◽  
Scanning Calorimetry ◽  
Angular Pressing ◽  
Analysis Technique ◽  
Properties Of Materials ◽  
Solid Liquid

Differential Scanning Calorimetry (DSC) is a thermal analysis technique that measures the energy absorbed or released by a sample as a function of temperature or time. DSC has wide application for analysis of solid state reactions and solid-liquid reactions in many different materials. In recent years, DSC has been applied to analyze materials and alloys processed through Severe Plastic Deformation (SPD). The basic principle of SPD processing is that a very high strain is introduced into materials which achieve significant grain refinement and improve properties of materials. This review paper presents some recent examples of the applications of DSC for materials subjected to SPD, especially by Equal-Channel Angular Pressing and High-Pressure Torsion.

Influence of Deformation on Precipitation Kinetics in Mg-Tb Alloy

2012 ◽  
Vol 322 ◽  
pp. 151-162 ◽  
Author(s):  
Oksana Melikhova ◽  
Jakub Čížek ◽  
Petr Hruška ◽  
Marián Vlček ◽  
Ivan Procházka ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
Positron Annihilation ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
Scanning Calorimetry ◽  
Fine Grained ◽  
Β Phase ◽  
Lower Temperature

Precipitation effects in age-hardenable Mg-13wt.%Tb alloy were investigated in this work. The solution treated alloy was subjected to isochronal annealing and decomposition of the supersaturated solid solution was investigated by positron annihilation spectroscopy combined with transmission electron microscopy, electrical resistometry, differential scanning calorimetry and microhardness measurements. Peak hardening was observed at 200°C due to precipitation of finely dispersed particles of β phase with the D019structure. Vacancy-like defects associated with β phase particles were detected by positron annihilation. At higher temperatures precipitation of β and subsequently β phase takes place. Formation of these phases lead to some additional hardening and introduces open volume defects at precipitate/matrix interfaces. To elucidate the effect of plastic deformation on the precipitation sequence we studied also a Mg-13wt.%Tb alloy with ultra fine grained structure prepared by high pressure torsion. In the ultra fine grained alloy precipitation of the β phase occurs at lower temperature compared to the coarse grained material and the peak hardening is shifted to a lower temperature as well. This effect can be explained by enhanced diffusivity of Mg and Tb atoms due to a dense network of grain boundaries and high density of dislocations introduced by severe plastic deformation. Moreover, dislocations and grain boundaries serve also as nucleation sites for precipitates. Hence, precipitation effects are accelerated in the alloy subjected to severe plastic deformation.

scholarly journals Processing of Nanostructured Bulk Fe-Cr Alloys by Severe Plastic Deformation

2021 ◽  
Vol 1016 ◽  
pp. 1603-1610
Author(s):  
Lukas Weissitsch ◽  
Martin Stückler ◽  
Stefan Wurster ◽  
Richard Pippan ◽  
Andrea Bachmaier
Keyword(s):  
Electron Microscopy ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Thermodynamical Equilibrium ◽  
X Ray ◽  
Σ Phase ◽  
Arc Melting

The processing of binary alloys consisting of ferromagnetic Fe and antiferromagnetic Cr by severe plastic deformation (SPD) with different chemical compositions has been investigated. Although the phase diagram exhibits a large gap in the thermodynamical equilibrium at lower temperatures, it is shown that techniques based on SPD help to overcome common processing limits. Different processing routes including initial ball milling (BM) and arc melting (AM) and a concatenation with annealing treatments prior to high-pressure torsion (HPT) deformation are compared in this work. Investigation of the deformed microstructures by electron microscopy and synchrotron X-ray diffraction reveal homogeneous, nanocrystalline microstructures for HPT deformed AM alloys. HPT deformation of powder blends and BM powders leads to an exorbitant increase in hardness or an unusual fast formation of a σ-phase and therefore impede successful processing.

CRYSTALLIZATION BEHAVIOR OF AMORPHOUS TI-NI-CU ALLOY RIBBONS

2008 ◽  
Vol 01 (02) ◽  
pp. 145-149 ◽  
Author(s):  
JUNG MIN NAM ◽  
YONG HEE LEE ◽  
TAE HYUN NAM ◽  
YEON WOOK KIM ◽  
JUNG MOO LEE
Keyword(s):  
Melt Spinning ◽  
Crystallization Behavior ◽  
Glass Forming Ability ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cu Content ◽  
Glass Forming ◽  
Cu Alloy ◽  
Transmission Electron

Amorphous Ti 50 Ni (50-x) Cu x (at.%) (x = 15, 20 and 25) alloy ribbons were prepared by melt spinning, and then their crystallization behavior was investigated by optical microscopy, transmission electron microscopy, X-ray diffraction and differential scanning calorimetry. Wavenumber (Qp) decreased from 29.40 nm-1 to 29.29 nm-1 and ΔT(T g - T x ) increased from 31 K to 36 K with increasing Cu content from 15 at.% to 25 at.%, suggesting that glass forming ability of Ti – Ni – Cu alloy ribbons increased with increasing Cu content. Activation energy for crystallization decreased from 211.5 kJ/mol to 136.4 kJ/mol with increasing Cu content from 15 at.% to 25 at.%, suggesting that a stability of Ti – Ni – Cu amorphous decreased with increasing Cu content.

Influence of Severe Plastic Deformation on Physicomechanical Properties of Ti-40 mas % Nb Alloy

2016 ◽  
Vol 685 ◽  
pp. 525-529
Author(s):  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Andrey V. Belyakov ◽  
Ivan A. Shulepov
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Cold Working ◽  
Young Modulus ◽  
Physicomechanical Properties ◽  
X Ray Diffraction ◽  
Refined Grains ◽  
X Ray ◽  
Initial Alloy ◽  
Composition Structure

The changes of the phase composition, structure and physicomechanical properties of Ti‑40 mas % Nb after severe plastic deformation are investigated in this paper. By the methods of microstructural, X-ray diffraction analysis and scanning electron microscopy it is determined that phase and structural transformations occur simultaneously in the alloy after severe plastic deformation. The martensitic structure formed after tempering disappears. The inverse α'' → β transformation occurs. The structure consisting of oriented refined grains is formed. The alloy is hardened due to the cold working. The Young modulus is equal to 79 GPa and it is less than that of initial alloy and close to the value obtained after tempering. It is possible that Young modulus is reduced by additional annealing.

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