The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Radim Kocich - One of the best experts on this subject based on the ideXlab platform.
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Texture and residual stress within rotary swaged Cu/Al clad composites
Materials Letters, 2018Co-Authors: Lenka Kunčická, Radim Kocich, Pavel Strunz, Adéla MacháčkováAbstract:Abstract Innovative Cu/Al clad composites with unique sequencing were rotary swaged at 20 °C and 250 °C with various swaging degrees. The analyses carried out by electron microscopies and neutron diffraction focused on deformation behaviour of the component metals, grains orientations, occurrence of residual stress and possible development of intermetallic phases on the interfaces. The results showed the swaging temperature and total Imposed Strain to have significant influences on all the investigated parameters. The Al wires cross-sections within the composites were affected by the increasing total Imposed Strain more at 250 °C, these composites also exhibited formation of intermetallics at higher swaging degrees. However, according to the neutron diffraction results, all the swaged composites experienced structure restoration resulting in residual stress relaxation despite the fact that they exhibited texture formation. Rotary swaging was proven to be applicable for production of Cu/Al clad composite wires in the industrial scale.
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A study of plastic deformation behaviour of Ti alloy during equal channel angular pressing with partial back pressure
Computational Materials Science, 2015Co-Authors: Radim Kocich, Adéla Macháčková, V. A. AndreyachshenkoAbstract:Abstract Equal channel angular pressing with partial back pressure (ECAP PBP) accumulates large Strains in a processed sample, while extruding it through a die with a modified geometry. In order to investigate the deformation behaviour of Ti6Al4V in detail, an ECAP PBP three-dimensional finite element model has been developed using FORGE software. The analysis included the influence of geometry and heterogeneity of plastic deformation. Numerical results showed that partial back pressure, as well as the other modelled factors, significantly affects size and homogeneity of the Imposed Strain, temperature and stability of material plastic flow. Average value of Imposed Strain was ∼1.58. Strain distribution was the most homogenous for the higher friction coefficient; its homogeneity was confirmed by micro-hardness testing. The results show the lowest temperature increase of the billet during ECAP PBP process. Using the partial back pressure, dead zone was eliminated. It also featured the highest reduction of tensile stress when compared to other processes. During the process with partial back pressure, the punch experienced 20% lower load compared to conventional ECAP with back pressure.
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Twist channel angular pressing (TCAP) as a method for increasing the efficiency of SPD
IOP Conference Series: Materials Science and Engineering, 2014Co-Authors: Radim Kocich, Miroslav Kursa, Ivo Szurman, Miroslav Greger, Adéla MacháčkováAbstract:The paper proposes a new variation for the application of SPD methods. Suggested TCAP (twisted channel angular pressing) technology obtains the larger Imposed Strain more effectively while increasing homogeneity of material. The number of passes needed to obtain the ultra-fine to nano-scale grains in bulk materials can be significantly reduced. Commercially pure copper (99.97%) was used for the experimental verification of the suggested process. The thermal stability of extruded copper was studied after the application of two modes of heat treatment. The deformation parameters of the process were also described using the numerical simulation based on FEM analysis. Predicted value of Imposed Strain, after a single pass, reached approximately 2.3. Measured strength, determined after four passes, achieved values around 440 MPa homogeneously along the cross-section of the extruded material. The grain size, determined after four passes, averaged out 1.2 μm. Homogeneity of deformation was also confirmed by micro-hardness tests.
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Twist channel multi-angular pressing (TCMAP) as a new SPD process: Numerical and experimental study
Materials Science and Engineering: A, 2014Co-Authors: Radim Kocich, Adéla Macháčková, Lenka KunčickáAbstract:Abstract The paper proposes a new variation for the application of SPD methods. Suggested twisted channel multi-angular pressing (TCMAP) technology obtains the larger Imposed Strain more effectively while increasing homogeneity of the material. The number of passes needed to obtain the ultra-fine to nano-scale grains in bulk materials can be significantly reduced. Commercially pure Al (99.97%) was used for the experimental verification of the suggested process. The deformation behavior of the material during the process was also described using the numerical simulation based on FE analysis. It was proved that the geometric parameters of the die, as well as the used individual deformation sections sequence, can significantly affect the size and homogeneity of the Imposed Strain or stability of the plastic flow of material. Predicted value of Imposed Strain, after a single pass, reached approximately 2.8. It is obvious that during the TCMAP process no dead zones occurred in any of the channel deformation sections. Due to designed shape of channel are both ends of processed sample defined by higher Imposed Strain and only negligible shape changes. A comparison between the FEM and experimental results of the required loads and the homogeneity of the Imposed Strain distribution showed good agreement. The high homogeneity of the distribution of the deformation was confirmed by micro-hardness testing, whereas a relative growth of 97% was documented after the first pass. The grain size, determined after TCMAP pass, averaged out to be 2.4 μm.
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The influence of Imposed Strain on the development of microstructure and transformation characteristics of Ni–Ti shape memory alloys
Journal of Alloys and Compounds, 2011Co-Authors: Radim Kocich, Miroslav Kursa, Ivo Szurman, Antonín DlouhýAbstract:Abstract Presented paper describes the influence of Imposed Strain on the development of microstructure (substructure) in Ni–Ti materials during the application of ECAE (equal channel angular extrusion). The interrelationship between Imposed Strain and resulting transformation characteristics is in the main point of interest while the chemical composition, namely the occurrence of secondary phases such as TiC and Ti 4 Ni 2 O resulting from the technology used for the sample alloy preparation is also investigated. The alloy Ni50.6–Ti (at.%) was prepared by melting in the HF vacuum induction furnace using a graphite crucible. The deformation was carried out via ECAE combined with prior rotary forging/swaging. ECAE was carried out at 280 °C. The Imposed Strain had the value ∼2. The alloy was processed by deformation route Bc. It was established the high dislocation density generated by the Imposed Strain stabilized the B2 and R phases and shifted the transformation R ↔ B19′ towards the lower temperature region. Direct effect of the deformation stress was demonstrated in samples after the second pass when the occurrence of the deformation induced transformation B2 → B19′ was confirmed. Deformation induced transformation also represents contribution to the overall deformation of the samples during the process.
Chuanbin Wang - One of the best experts on this subject based on the ideXlab platform.
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substrate Imposed Strain engineering of multiferroic properties in bczt lcmo bilayer heterostructures
Applied Surface Science, 2020Co-Authors: Chuanbin WangAbstract:Abstract Ba0.85Ca0.15Zr0.9Ti0.1O3/La0.67Ca0.33MnO3 (BCZT/LCMO) bilayer epitaxial heterostructures were deposited on LaAlO3 (LAO), (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) and SrTiO3 (STO) single-crystalline substrates by using pulsed laser deposition, to investigate the substrate-Imposed Strain engineering of multiferroic properties. The epitaxial growth and the Strain state of the as-deposited bilayer heterostructures were determined by X-ray reciprocal space mapping analysis. Results showed that the substrate-Imposed Strain engineering could turn the multiferroic properties by modulating the polarization switching and domain wall motion of the bilayer heterostructures. The optimal dielectric, ferroelectric and piezoelectric performances were obtained in the bilayer heterostructure deposited on STO substrate while an improved saturated magnetization was achieved in the bilayer heterostructure deposited on LAO substrate. The maximum magnetoelectric coupling was obtained in the bilayer heterostructure deposited on STO substrate with αE31 value of 61.2 mV/cm·Oe.
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Substrate-Imposed Strain engineering of multiferroic properties in BCZT/LCMO bilayer heterostructures
Applied Surface Science, 2020Co-Authors: Chuanbin WangAbstract:Abstract Ba0.85Ca0.15Zr0.9Ti0.1O3/La0.67Ca0.33MnO3 (BCZT/LCMO) bilayer epitaxial heterostructures were deposited on LaAlO3 (LAO), (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) and SrTiO3 (STO) single-crystalline substrates by using pulsed laser deposition, to investigate the substrate-Imposed Strain engineering of multiferroic properties. The epitaxial growth and the Strain state of the as-deposited bilayer heterostructures were determined by X-ray reciprocal space mapping analysis. Results showed that the substrate-Imposed Strain engineering could turn the multiferroic properties by modulating the polarization switching and domain wall motion of the bilayer heterostructures. The optimal dielectric, ferroelectric and piezoelectric performances were obtained in the bilayer heterostructure deposited on STO substrate while an improved saturated magnetization was achieved in the bilayer heterostructure deposited on LAO substrate. The maximum magnetoelectric coupling was obtained in the bilayer heterostructure deposited on STO substrate with αE31 value of 61.2 mV/cm·Oe.
Adéla Macháčková - One of the best experts on this subject based on the ideXlab platform.
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Texture and residual stress within rotary swaged Cu/Al clad composites
Materials Letters, 2018Co-Authors: Lenka Kunčická, Radim Kocich, Pavel Strunz, Adéla MacháčkováAbstract:Abstract Innovative Cu/Al clad composites with unique sequencing were rotary swaged at 20 °C and 250 °C with various swaging degrees. The analyses carried out by electron microscopies and neutron diffraction focused on deformation behaviour of the component metals, grains orientations, occurrence of residual stress and possible development of intermetallic phases on the interfaces. The results showed the swaging temperature and total Imposed Strain to have significant influences on all the investigated parameters. The Al wires cross-sections within the composites were affected by the increasing total Imposed Strain more at 250 °C, these composites also exhibited formation of intermetallics at higher swaging degrees. However, according to the neutron diffraction results, all the swaged composites experienced structure restoration resulting in residual stress relaxation despite the fact that they exhibited texture formation. Rotary swaging was proven to be applicable for production of Cu/Al clad composite wires in the industrial scale.
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A study of plastic deformation behaviour of Ti alloy during equal channel angular pressing with partial back pressure
Computational Materials Science, 2015Co-Authors: Radim Kocich, Adéla Macháčková, V. A. AndreyachshenkoAbstract:Abstract Equal channel angular pressing with partial back pressure (ECAP PBP) accumulates large Strains in a processed sample, while extruding it through a die with a modified geometry. In order to investigate the deformation behaviour of Ti6Al4V in detail, an ECAP PBP three-dimensional finite element model has been developed using FORGE software. The analysis included the influence of geometry and heterogeneity of plastic deformation. Numerical results showed that partial back pressure, as well as the other modelled factors, significantly affects size and homogeneity of the Imposed Strain, temperature and stability of material plastic flow. Average value of Imposed Strain was ∼1.58. Strain distribution was the most homogenous for the higher friction coefficient; its homogeneity was confirmed by micro-hardness testing. The results show the lowest temperature increase of the billet during ECAP PBP process. Using the partial back pressure, dead zone was eliminated. It also featured the highest reduction of tensile stress when compared to other processes. During the process with partial back pressure, the punch experienced 20% lower load compared to conventional ECAP with back pressure.
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Twist channel angular pressing (TCAP) as a method for increasing the efficiency of SPD
IOP Conference Series: Materials Science and Engineering, 2014Co-Authors: Radim Kocich, Miroslav Kursa, Ivo Szurman, Miroslav Greger, Adéla MacháčkováAbstract:The paper proposes a new variation for the application of SPD methods. Suggested TCAP (twisted channel angular pressing) technology obtains the larger Imposed Strain more effectively while increasing homogeneity of material. The number of passes needed to obtain the ultra-fine to nano-scale grains in bulk materials can be significantly reduced. Commercially pure copper (99.97%) was used for the experimental verification of the suggested process. The thermal stability of extruded copper was studied after the application of two modes of heat treatment. The deformation parameters of the process were also described using the numerical simulation based on FEM analysis. Predicted value of Imposed Strain, after a single pass, reached approximately 2.3. Measured strength, determined after four passes, achieved values around 440 MPa homogeneously along the cross-section of the extruded material. The grain size, determined after four passes, averaged out 1.2 μm. Homogeneity of deformation was also confirmed by micro-hardness tests.
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Twist channel multi-angular pressing (TCMAP) as a new SPD process: Numerical and experimental study
Materials Science and Engineering: A, 2014Co-Authors: Radim Kocich, Adéla Macháčková, Lenka KunčickáAbstract:Abstract The paper proposes a new variation for the application of SPD methods. Suggested twisted channel multi-angular pressing (TCMAP) technology obtains the larger Imposed Strain more effectively while increasing homogeneity of the material. The number of passes needed to obtain the ultra-fine to nano-scale grains in bulk materials can be significantly reduced. Commercially pure Al (99.97%) was used for the experimental verification of the suggested process. The deformation behavior of the material during the process was also described using the numerical simulation based on FE analysis. It was proved that the geometric parameters of the die, as well as the used individual deformation sections sequence, can significantly affect the size and homogeneity of the Imposed Strain or stability of the plastic flow of material. Predicted value of Imposed Strain, after a single pass, reached approximately 2.8. It is obvious that during the TCMAP process no dead zones occurred in any of the channel deformation sections. Due to designed shape of channel are both ends of processed sample defined by higher Imposed Strain and only negligible shape changes. A comparison between the FEM and experimental results of the required loads and the homogeneity of the Imposed Strain distribution showed good agreement. The high homogeneity of the distribution of the deformation was confirmed by micro-hardness testing, whereas a relative growth of 97% was documented after the first pass. The grain size, determined after TCMAP pass, averaged out to be 2.4 μm.
Lenka Kunčická - One of the best experts on this subject based on the ideXlab platform.
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Structure Characteristics Affected by Material Plastic Flow in Twist Channel Angular Pressed Al/Cu Clad Composites.
Materials (Basel Switzerland), 2020Co-Authors: Lenka Kunčická, Zuzana KlečkováAbstract:The study focuses on structure analyses, texture analyses in particular, of an Al/Cu clad composite manufactured by single and double pass of the twist channel angular pressing (TCAP) method. Microscopic analyses were supplemented with numerical predictions focused on the effective Imposed Strain and material plastic flow, and microhardness measurements. Both the TCAP passes imparted characteristic texture orientations to the reinforcing Cu wires, however, the individual preferential grains’ orientations throughout the composite differed and depended on the location of the particular wire within the Al sheath during extrusion, i.e., on the dominant acting Strain path. The second TCAP pass resulted in texture homogenization; all the Cu wires finally exhibited dominant A fiber shear texture. This finding was in accordance with the homogenization of the Imposed Strain predicted after the second TCAP pass. The results also revealed that both the component metals exhibited significant deformation strengthening (which also caused bending of the ends of the Cu wires within the Al sheath after extrusion). The average microhardness of the Cu wires after the second pass reached up to 128 HV, while for the Al sheath the value was 86 HV.
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Texture and residual stress within rotary swaged Cu/Al clad composites
Materials Letters, 2018Co-Authors: Lenka Kunčická, Radim Kocich, Pavel Strunz, Adéla MacháčkováAbstract:Abstract Innovative Cu/Al clad composites with unique sequencing were rotary swaged at 20 °C and 250 °C with various swaging degrees. The analyses carried out by electron microscopies and neutron diffraction focused on deformation behaviour of the component metals, grains orientations, occurrence of residual stress and possible development of intermetallic phases on the interfaces. The results showed the swaging temperature and total Imposed Strain to have significant influences on all the investigated parameters. The Al wires cross-sections within the composites were affected by the increasing total Imposed Strain more at 250 °C, these composites also exhibited formation of intermetallics at higher swaging degrees. However, according to the neutron diffraction results, all the swaged composites experienced structure restoration resulting in residual stress relaxation despite the fact that they exhibited texture formation. Rotary swaging was proven to be applicable for production of Cu/Al clad composite wires in the industrial scale.
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Twist channel multi-angular pressing (TCMAP) as a new SPD process: Numerical and experimental study
Materials Science and Engineering: A, 2014Co-Authors: Radim Kocich, Adéla Macháčková, Lenka KunčickáAbstract:Abstract The paper proposes a new variation for the application of SPD methods. Suggested twisted channel multi-angular pressing (TCMAP) technology obtains the larger Imposed Strain more effectively while increasing homogeneity of the material. The number of passes needed to obtain the ultra-fine to nano-scale grains in bulk materials can be significantly reduced. Commercially pure Al (99.97%) was used for the experimental verification of the suggested process. The deformation behavior of the material during the process was also described using the numerical simulation based on FE analysis. It was proved that the geometric parameters of the die, as well as the used individual deformation sections sequence, can significantly affect the size and homogeneity of the Imposed Strain or stability of the plastic flow of material. Predicted value of Imposed Strain, after a single pass, reached approximately 2.8. It is obvious that during the TCMAP process no dead zones occurred in any of the channel deformation sections. Due to designed shape of channel are both ends of processed sample defined by higher Imposed Strain and only negligible shape changes. A comparison between the FEM and experimental results of the required loads and the homogeneity of the Imposed Strain distribution showed good agreement. The high homogeneity of the distribution of the deformation was confirmed by micro-hardness testing, whereas a relative growth of 97% was documented after the first pass. The grain size, determined after TCMAP pass, averaged out to be 2.4 μm.
Nik Petrinic - One of the best experts on this subject based on the ideXlab platform.
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Measurements of the effects of pure and salt water absorption on the rate-dependent response of an epoxy matrix
Composites Part B: Engineering, 2018Co-Authors: Gustavo Quino, Antonio Pellegrino, V L Tagarielli, Nik PetrinicAbstract:Abstract The study reports the measured effects of water absorption on an epoxy resin. Epoxy samples were exposed to wet conditioning environments including pure water, NaCl-water solution, and pure water at boiling temperature, measuring absorption as a function of time. Vickers hardness and indentation creep tests were performed and the mechanical response of the material to uniaxial stress was also measured in both compression and tension, at Imposed Strain rates in the range 0.001–2500 s−1. It was found that the absorption of both pure and salt water caused decrease of stiffness, yield stress and hardness, but only mildly affected the sensitivity of the response to the Imposed Strain rate and the tensile ductility. Mechanical testing after re-drying of the samples revealed the permanent effects of water absorption.
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the mechanical response of a syntactic polyurethane foam at low and high rates of Strain
International Journal of Impact Engineering, 2015Co-Authors: Antonio Pellegrino, V L Tagarielli, Robert Gerlach, Nik PetrinicAbstract:Abstract Quasi-static and dynamic experiments are conducted to characterise the mechanical response of a syntactic foam comprising hollow glass microballoons in a polyurethane matrix. Stress versus Strain histories are measured in uniaxial tension and compression as well as in pure shear, at Strain rates ranging from 10 −4 to 10 3 s −1 , via non-standard experimental techniques; quasi-static in-situ tests are conducted to visualise the deformation mechanisms in tension and compression. The material displays a pronounced sensitivity to the Imposed Strain rate and relatively high tensile and shear ductility at both low and high Strain rates. A tension/compression asymmetry is displayed in quasi-static tests but is lost at high rates of Strain.
