Malki Pinkas - Academia.edu (original) (raw)

Papers by Malki Pinkas

Research paper thumbnail of Dynamic Versus Quasi Static Fracture Toughness of Additively Manufactured AlSi10Mg Alloy by Selective Laser Melting Technique

Analele Universităţii "Dunărea de Jos" din Galaţi, Dec 28, 2018

Research paper thumbnail of A crystallographic study of the deformation mechanisms during small punch testing of 14wt%Cr oxide dispersion steel

Journal of Materials Science, Jun 8, 2022

Research paper thumbnail of Systematic study of the effect of Cr on the microstructure, phase content and hardness of the AlCrxFeCoNi alloys

Journal of Alloys and Compounds

Research paper thumbnail of Ion irradiation effect on B2 single phase AlFeCoNi alloy

Materials Characterization

Research paper thumbnail of Long-period antiphase domains and short-range order in a B2 matrix of the AlCoCrFeNi high-entropy alloy

Research paper thumbnail of The role of In or Pd additions in Al2O3/metal composite growth by melt oxidation in the Al-Mg-O system

Research paper thumbnail of Evolution of Ti-Based Nonmetallic Inclusions During Solution Treatment of Maraging 250 Steel: Thermodynamic Calculations and Experimental Verification

Metallurgical and Materials Transactions B, 2011

Research paper thumbnail of Early stages of interface reactions between AlN and Ti thin films

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2002

ABSTRACT The early stages of interface reactions between AlN and Ti thin films were investigated ... more ABSTRACT The early stages of interface reactions between AlN and Ti thin films were investigated using x-ray diffractions, Auger electron spectroscopy, cross section transmission electron microscopy (XTEM), and high resolution XTEM. The AlN/Ti bilayers were deposited on a molybdenum substrate using reactive and nonreactive magnetron sputtering techniques. After deposition, the bilayers were heat treated for 1-10 h at 600 °C in a nitrogen atmosphere. Decomposition of the AlN layer took place at the AlN/Ti interface and its products, Al and N, reacted with Ti to produce a AlN/Al3Ti/Ti2N/Ti3Al/alpha-(Ti, Al)ss phase sequence. This phase sequence is not consistent with the Ti-Al-N phase diagram and is believed to be the outcome of the particular conditions that prevail in the thin film and correspond to a particular set of kinetic parameters. A model that explains the development of the phase sequence and predicts its evolution after prolonged heat treatments is put forward. The applicability of such a solid-state reaction technique for producing functionally graded coating for wear and corrosion resistance applications is discussed.

Research paper thumbnail of Assessment of Hydrogen-Induced Precipitation in a Nickel-Copper Alloy Using Thermoelectric Power

Research paper thumbnail of Microstructure characterization of ceramic composites formed by controlled melt oxidation of Al-Mg-Pd alloys

... The results of the present study indicate that the di-rected melt oxidation process can be co... more ... The results of the present study indicate that the di-rected melt oxidation process can be controlled by an appropriate choice of the elements added to the basic Al-Mg alloy. ... 12. K. C. VLACH, O. SALAS, H. NI, V. JAYARAM, C. G. LEVI and R. MEHRABIAN, J. Mater. Res. ...

Research paper thumbnail of Influence of alloying elements and the state of order on the formation of antiphase boundaries in B2 phases

Research paper thumbnail of Understanding the Role of the Constituting Elements of the AlCoCrFeNi High Entropy Alloy through the Investigation of Quaternary Alloys

Metals

Quinary AlCoCrFeNi high entropy alloy (HEA) is one of the most studied alloys in the recent decad... more Quinary AlCoCrFeNi high entropy alloy (HEA) is one of the most studied alloys in the recent decade due to its outstanding properties. However, it is still far from becoming an applicable industrial alloy. To our understanding, in order to promote this, the role of elements, constituting the quinary alloy, needs to be defined. Knowing the role of each element, modification of the quinary alloy toward minimization of its disadvantages will be possible. In the current research, we shed some light on this subject, presenting a thorough investigation of the microstructure (carried out using scanning and transmission electron microscopy) and mechanical properties, performed by microhardness and fractography post small punch test (SPT), of five equiatomic quaternary alloys, constituting the quinary system, namely: CoCrFeNi, AlCoFeNi, AlCoCrNi, AlCoCrFe, and AlCrFeNi. CoCrFeNi (i.e., w/o Al) was found to be Face Centered Cubic (FCC) solid solution, exhibiting relatively low micro-hardness a...

Research paper thumbnail of Kinetics of the α-α′ phase separation in a 14%Cr oxide dispersion steel at intermediate temperatures

Research paper thumbnail of Characterization of nano-sized particles in 14%Cr oxide dispersion strengthened (ODS) steel using classical and frontier microscopy methods

Materials Characterization

Abstract Oxide dispersion strengthened (ODS) steels exhibit superior mechanical properties and ir... more Abstract Oxide dispersion strengthened (ODS) steels exhibit superior mechanical properties and irradiation resistance due to nano-sized oxides, highly dispersed in the metallic matrix. The mechanical properties are affected by the structure, composition, size and density of the nano-sized oxides. Despite numerous reports on the characterization of these oxides, ambiguity regarding their composition, crystallographic structure and orientation relationship with the matrix remains. In the present study, characterization of the crystallographic structure of oxide particles existing in 14%Cr ODS steel was performed using classical and novel transmission electron microscopy (TEM) methods. 3D dispersion, density and composition of these oxides were evaluated by atom probe tomography (APT). Three populations of particles were detected: highly dispersed, 3–20 nm Fe(Cr,Ti,Y)O particles with spinel structure; 50–150 nm YTiO3 and large (100–200 nm) particles identified as cubic TiC. The spinel-type particles displayed Bain and Kurdjumov-Sachs orientation relationships (OR) with the ferritic matrix. Applying electron diffraction tomography, the YTiO3 structure was attributed to the GdFeO3 (distorted perovskite)-type and its lattice parameters were refined as a = 5.46 A, b = 7.66 A and c = 5.28 A. Orientation relationship of the YTiO3 particles and Fe matrix were determined as [110]Fe//[210]oxide and (110)Fe//(002)oxide.

Research paper thumbnail of Retardation of the σ phase formation in the AlCoCrFeNi multi-component alloy

Materials Characterization

Research paper thumbnail of The relation between aging temperature, microstructure evolution and hardening of Custom 465® stainless steel

Materials Characterization, 2017

Research paper thumbnail of Structure and properties of selected (Cr�Al�N, TiC�C, Cr�B�N) nanostructured tribological coatings

International Journal of Refractory Metals and Hard Materials, 2010

Research paper thumbnail of Pulsed Closed Field Unbalanced Magnetron Sputtering (P-CFUBMS) Deposited TiC/a:C Thin Films

Materials Science Forum, 2007

TiC/a:C nanocomposite thin film has proven to be a worthy material selection as a thin film for t... more TiC/a:C nanocomposite thin film has proven to be a worthy material selection as a thin film for tribological applications due to its low coefficient of friction, good wear resistance and high hardness. In the current study TiC/a:C thin films with carbon concentration near 55-62 at % were deposited via pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) in pure argon atmosphere with different substrate bias voltages and onto 440C stainless steel substrate with different substrate roughness. It was found that the TiC/a:C film hardness and elastic modulus were increased from 18.5 GPa to 33.8 GPa by increasing the substrate bias from floating to -150 V. However higher substrate bias can also decrease the film tibological properties. The substrate roughness has a strong effect on TiC/a:C film wear behavior. When the Ra (Mean surface roughness values) is less than 110 nm, the COF values are in low range (0.18-0.28). Further increase the Ra value to above 300 nm will result in a higher COF (>0.33). Films deposited on higher surface roughness substrate need longer time to reach the sliding equilibrium state.

Research paper thumbnail of The origin of the effect of aging on the thermoelectric power of maraging C250 steel

Journal of Materials Science, 2015

ABSTRACT

Research paper thumbnail of Processing, Structure, and Properties of Nanostructured Multifunctional Tribological Coatings

Nanostructured, nanocomposite binary (TiC-a:C), ternary (Cr-Al-N), quaternary (Ti-B-C-N) and quin... more Nanostructured, nanocomposite binary (TiC-a:C), ternary (Cr-Al-N), quaternary (Ti-B-C-N) and quinternary (Ti-Si-B-C-N) multicomponent films have been deposited using unbalanced magnetron sputtering (UBMS) and closed field unbalanced magnetron sputtering (CFUBMS) from both elemental and composite targets. Approaches to control the film chemistry, volume fraction and size of the multicomponent species, and pulsed ion energy (ion flux) bombardment to tailor the structure and properties of the films for specific tribological applications, e.g., low friction coefficient and low wear rate, are emphasized. The synthesized films are characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nanoindentation, and microtribometry. The relationships between processing parameters (pulsed ion energy and ion flux), thin film microstructure, mechanical and tribological properties are being investigated in terms of the nanocrystalline-nanocrystalline and nanocrystalline-amorphous composite thin film systems that are generated. In the Ti-Si-B-C-N films, nanocomposites of solid solutions, e.g., nanosized (Ti,C,N)B2 and Ti(C,N) crystallites are embedded in an amorphous TiSi2 and SiC matrix including some carbon, SiB4, BN, CN(x), TiO2 and B2O3 components. The Ti-Si-B-C-N coating with up to 150 W Si target power exhibited a hardness of about 35 GPa, a high H/E ratio of 0.095, and a low wear rate of from approximately 3 to approximately 10 x 10(-6) mm3/(Nm). In another aspect, using increased ion energy and ion flux, which are generated by pulsing the power of the target(s) in a closed field arrangement, to provide improved ion bombardment on tailoring the structure and properties of TiC-a:C and Cr-Al-N coatings are demonstrated. It was found that highly energetic species (up to hundreds eV) were found in the plasma by pulsing the power of the target(s) during magnetron sputtering. Applying higher pulse frequency and longer reverse time (lower duty cycle) will result in higher ion energy and ion flux in the plasma, which can be utilized to improve the film structure and properties. For example, optimum properties of the TiC-a:C coating were a hardness of 35 to 40 GPa and a COF of 0.2 to 0.22 for moderate maximum ion energies of 70 to 100 eV, and a super high hardness of 41 GPa and low wear rate of 3.41 x 10(-6) mm3N(-1) m(-1) was obtained for Cr-Al-N coatings deposited with a maximum ion energy of 122 eV. These conditions can be achieved by adjusting the pulsing parameters and target voltages. However, the pulsed ion energy together with the applied substrate bias are need to be carefully controlled in order to avoid excessive ion bombardment (e.g., the maximum ion energy is larger than 180 eV in the current study), which will responsible for an increase in point and line defects, and high residual stress in the crystalline structure.

Research paper thumbnail of Dynamic Versus Quasi Static Fracture Toughness of Additively Manufactured AlSi10Mg Alloy by Selective Laser Melting Technique

Analele Universităţii "Dunărea de Jos" din Galaţi, Dec 28, 2018

Research paper thumbnail of A crystallographic study of the deformation mechanisms during small punch testing of 14wt%Cr oxide dispersion steel

Journal of Materials Science, Jun 8, 2022

Research paper thumbnail of Systematic study of the effect of Cr on the microstructure, phase content and hardness of the AlCrxFeCoNi alloys

Journal of Alloys and Compounds

Research paper thumbnail of Ion irradiation effect on B2 single phase AlFeCoNi alloy

Materials Characterization

Research paper thumbnail of Long-period antiphase domains and short-range order in a B2 matrix of the AlCoCrFeNi high-entropy alloy

Research paper thumbnail of The role of In or Pd additions in Al2O3/metal composite growth by melt oxidation in the Al-Mg-O system

Research paper thumbnail of Evolution of Ti-Based Nonmetallic Inclusions During Solution Treatment of Maraging 250 Steel: Thermodynamic Calculations and Experimental Verification

Metallurgical and Materials Transactions B, 2011

Research paper thumbnail of Early stages of interface reactions between AlN and Ti thin films

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2002

ABSTRACT The early stages of interface reactions between AlN and Ti thin films were investigated ... more ABSTRACT The early stages of interface reactions between AlN and Ti thin films were investigated using x-ray diffractions, Auger electron spectroscopy, cross section transmission electron microscopy (XTEM), and high resolution XTEM. The AlN/Ti bilayers were deposited on a molybdenum substrate using reactive and nonreactive magnetron sputtering techniques. After deposition, the bilayers were heat treated for 1-10 h at 600 °C in a nitrogen atmosphere. Decomposition of the AlN layer took place at the AlN/Ti interface and its products, Al and N, reacted with Ti to produce a AlN/Al3Ti/Ti2N/Ti3Al/alpha-(Ti, Al)ss phase sequence. This phase sequence is not consistent with the Ti-Al-N phase diagram and is believed to be the outcome of the particular conditions that prevail in the thin film and correspond to a particular set of kinetic parameters. A model that explains the development of the phase sequence and predicts its evolution after prolonged heat treatments is put forward. The applicability of such a solid-state reaction technique for producing functionally graded coating for wear and corrosion resistance applications is discussed.

Research paper thumbnail of Assessment of Hydrogen-Induced Precipitation in a Nickel-Copper Alloy Using Thermoelectric Power

Research paper thumbnail of Microstructure characterization of ceramic composites formed by controlled melt oxidation of Al-Mg-Pd alloys

... The results of the present study indicate that the di-rected melt oxidation process can be co... more ... The results of the present study indicate that the di-rected melt oxidation process can be controlled by an appropriate choice of the elements added to the basic Al-Mg alloy. ... 12. K. C. VLACH, O. SALAS, H. NI, V. JAYARAM, C. G. LEVI and R. MEHRABIAN, J. Mater. Res. ...

Research paper thumbnail of Influence of alloying elements and the state of order on the formation of antiphase boundaries in B2 phases

Research paper thumbnail of Understanding the Role of the Constituting Elements of the AlCoCrFeNi High Entropy Alloy through the Investigation of Quaternary Alloys

Metals

Quinary AlCoCrFeNi high entropy alloy (HEA) is one of the most studied alloys in the recent decad... more Quinary AlCoCrFeNi high entropy alloy (HEA) is one of the most studied alloys in the recent decade due to its outstanding properties. However, it is still far from becoming an applicable industrial alloy. To our understanding, in order to promote this, the role of elements, constituting the quinary alloy, needs to be defined. Knowing the role of each element, modification of the quinary alloy toward minimization of its disadvantages will be possible. In the current research, we shed some light on this subject, presenting a thorough investigation of the microstructure (carried out using scanning and transmission electron microscopy) and mechanical properties, performed by microhardness and fractography post small punch test (SPT), of five equiatomic quaternary alloys, constituting the quinary system, namely: CoCrFeNi, AlCoFeNi, AlCoCrNi, AlCoCrFe, and AlCrFeNi. CoCrFeNi (i.e., w/o Al) was found to be Face Centered Cubic (FCC) solid solution, exhibiting relatively low micro-hardness a...

Research paper thumbnail of Kinetics of the α-α′ phase separation in a 14%Cr oxide dispersion steel at intermediate temperatures

Research paper thumbnail of Characterization of nano-sized particles in 14%Cr oxide dispersion strengthened (ODS) steel using classical and frontier microscopy methods

Materials Characterization

Abstract Oxide dispersion strengthened (ODS) steels exhibit superior mechanical properties and ir... more Abstract Oxide dispersion strengthened (ODS) steels exhibit superior mechanical properties and irradiation resistance due to nano-sized oxides, highly dispersed in the metallic matrix. The mechanical properties are affected by the structure, composition, size and density of the nano-sized oxides. Despite numerous reports on the characterization of these oxides, ambiguity regarding their composition, crystallographic structure and orientation relationship with the matrix remains. In the present study, characterization of the crystallographic structure of oxide particles existing in 14%Cr ODS steel was performed using classical and novel transmission electron microscopy (TEM) methods. 3D dispersion, density and composition of these oxides were evaluated by atom probe tomography (APT). Three populations of particles were detected: highly dispersed, 3–20 nm Fe(Cr,Ti,Y)O particles with spinel structure; 50–150 nm YTiO3 and large (100–200 nm) particles identified as cubic TiC. The spinel-type particles displayed Bain and Kurdjumov-Sachs orientation relationships (OR) with the ferritic matrix. Applying electron diffraction tomography, the YTiO3 structure was attributed to the GdFeO3 (distorted perovskite)-type and its lattice parameters were refined as a = 5.46 A, b = 7.66 A and c = 5.28 A. Orientation relationship of the YTiO3 particles and Fe matrix were determined as [110]Fe//[210]oxide and (110)Fe//(002)oxide.

Research paper thumbnail of Retardation of the σ phase formation in the AlCoCrFeNi multi-component alloy

Materials Characterization

Research paper thumbnail of The relation between aging temperature, microstructure evolution and hardening of Custom 465® stainless steel

Materials Characterization, 2017

Research paper thumbnail of Structure and properties of selected (Cr�Al�N, TiC�C, Cr�B�N) nanostructured tribological coatings

International Journal of Refractory Metals and Hard Materials, 2010

Research paper thumbnail of Pulsed Closed Field Unbalanced Magnetron Sputtering (P-CFUBMS) Deposited TiC/a:C Thin Films

Materials Science Forum, 2007

TiC/a:C nanocomposite thin film has proven to be a worthy material selection as a thin film for t... more TiC/a:C nanocomposite thin film has proven to be a worthy material selection as a thin film for tribological applications due to its low coefficient of friction, good wear resistance and high hardness. In the current study TiC/a:C thin films with carbon concentration near 55-62 at % were deposited via pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) in pure argon atmosphere with different substrate bias voltages and onto 440C stainless steel substrate with different substrate roughness. It was found that the TiC/a:C film hardness and elastic modulus were increased from 18.5 GPa to 33.8 GPa by increasing the substrate bias from floating to -150 V. However higher substrate bias can also decrease the film tibological properties. The substrate roughness has a strong effect on TiC/a:C film wear behavior. When the Ra (Mean surface roughness values) is less than 110 nm, the COF values are in low range (0.18-0.28). Further increase the Ra value to above 300 nm will result in a higher COF (>0.33). Films deposited on higher surface roughness substrate need longer time to reach the sliding equilibrium state.

Research paper thumbnail of The origin of the effect of aging on the thermoelectric power of maraging C250 steel

Journal of Materials Science, 2015

ABSTRACT

Research paper thumbnail of Processing, Structure, and Properties of Nanostructured Multifunctional Tribological Coatings

Nanostructured, nanocomposite binary (TiC-a:C), ternary (Cr-Al-N), quaternary (Ti-B-C-N) and quin... more Nanostructured, nanocomposite binary (TiC-a:C), ternary (Cr-Al-N), quaternary (Ti-B-C-N) and quinternary (Ti-Si-B-C-N) multicomponent films have been deposited using unbalanced magnetron sputtering (UBMS) and closed field unbalanced magnetron sputtering (CFUBMS) from both elemental and composite targets. Approaches to control the film chemistry, volume fraction and size of the multicomponent species, and pulsed ion energy (ion flux) bombardment to tailor the structure and properties of the films for specific tribological applications, e.g., low friction coefficient and low wear rate, are emphasized. The synthesized films are characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nanoindentation, and microtribometry. The relationships between processing parameters (pulsed ion energy and ion flux), thin film microstructure, mechanical and tribological properties are being investigated in terms of the nanocrystalline-nanocrystalline and nanocrystalline-amorphous composite thin film systems that are generated. In the Ti-Si-B-C-N films, nanocomposites of solid solutions, e.g., nanosized (Ti,C,N)B2 and Ti(C,N) crystallites are embedded in an amorphous TiSi2 and SiC matrix including some carbon, SiB4, BN, CN(x), TiO2 and B2O3 components. The Ti-Si-B-C-N coating with up to 150 W Si target power exhibited a hardness of about 35 GPa, a high H/E ratio of 0.095, and a low wear rate of from approximately 3 to approximately 10 x 10(-6) mm3/(Nm). In another aspect, using increased ion energy and ion flux, which are generated by pulsing the power of the target(s) in a closed field arrangement, to provide improved ion bombardment on tailoring the structure and properties of TiC-a:C and Cr-Al-N coatings are demonstrated. It was found that highly energetic species (up to hundreds eV) were found in the plasma by pulsing the power of the target(s) during magnetron sputtering. Applying higher pulse frequency and longer reverse time (lower duty cycle) will result in higher ion energy and ion flux in the plasma, which can be utilized to improve the film structure and properties. For example, optimum properties of the TiC-a:C coating were a hardness of 35 to 40 GPa and a COF of 0.2 to 0.22 for moderate maximum ion energies of 70 to 100 eV, and a super high hardness of 41 GPa and low wear rate of 3.41 x 10(-6) mm3N(-1) m(-1) was obtained for Cr-Al-N coatings deposited with a maximum ion energy of 122 eV. These conditions can be achieved by adjusting the pulsing parameters and target voltages. However, the pulsed ion energy together with the applied substrate bias are need to be carefully controlled in order to avoid excessive ion bombardment (e.g., the maximum ion energy is larger than 180 eV in the current study), which will responsible for an increase in point and line defects, and high residual stress in the crystalline structure.