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Papers by Muhammad Zeeshan Khalid

Research paper thumbnail of Ab-initio study of atomic structure and mechanical behaviour of Al/Fe intermetallic interfaces

Computational Materials Science, 2020

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Research paper thumbnail of Modified embedded atom method potential for Fe-Al intermetallics mechanical strength: A comparative analysis of atomistic simulations

Physica B-condensed Matter, 2021

The structural and mechanical properties of Fe-Al compounds (FeAl, Fe 2 Al, Fe 3 Al, FeAl 2 , FeA... more The structural and mechanical properties of Fe-Al compounds (FeAl, Fe 2 Al, Fe 3 Al, FeAl 2 , FeAl 3 , Fe 2 Al 5 ) have been studied using modified embedded atom method (MEAM) potentials. The equilibrium lattice constants, formation enthalpies, and elastic properties have been investigated and compared with other studies. The calculated lattice constants show good agreement with the embedded atom method (EAM) and density functional theory (DFT) calculations and with experiments. All Fe-Al compounds are mechanically stable according to the elastic constants restrictions. The calculated bulk modulus of the compounds does not show a linear relation with Fe concentration, which is most probably caused by the mechanical anisotropy of Fe-Al compounds. However, comparison of the Fe-Al mechanical properties of MEAM, DFT and EAM-based approaches and experiments show non-consistent differences, which reflects uncertainties with several of these methods, due to assumptions and simplifications ...

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Research paper thumbnail of Modified embedded atom method potential for Fe-Al intermetallics mechanical strength: A comparative analysis of atomistic simulations

Physica B: Physics of Condensed Matter, 2021

The structural and mechanical properties of Fe-Al compounds (FeAl, Fe2Al, Fe3Al, FeAl2, FeAl3, Fe... more The structural and mechanical properties of Fe-Al compounds (FeAl, Fe2Al, Fe3Al, FeAl2, FeAl3, Fe2Al5) have been studied using modified embedded atom method (MEAM) potentials. The equilibrium lattice constants, formation enthalpies, and elastic properties have been investigated and compared with other studies. The calculated lattice constants show good agreement with the embedded atom method (EAM) and density functional theory (DFT) calculations and with experiments. All Fe-Al compounds are mechanically stable according to the elastic constants restrictions. The calculated bulk modulus of the compounds does not show a linear relation with Fe concentration, which is most probably caused by the mechanical anisotropy of Fe-Al compounds. However, comparison of the Fe-Al mechanical properties of MEAM, DFT and EAM-based approaches and experiments show non-consistent differences, which reflects uncertainties with several of these methods, due to assumptions and simplifications imposed during calculations. In general, DFT calculations are closer to experimental observations than semi-empirical potentials. Comprehensive comparisons are made based on theoretical and experimental methodologies.

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Research paper thumbnail of First-principles study of tensile and shear strength of an Fe 2 Al 5 // Fe interface

The interfacial strengths of a low misfit Fe2Al5//Fe interface structure found at aluminum-steel ... more The interfacial strengths of a low misfit Fe2Al5//Fe interface structure found at aluminum-steel joints has been studied using density functional theory. An interface between Fe and Fe2Al5 was selected based on a criteria of low lattice misfit and number of atoms. Through virtual tensile testing of bulk Fe2Al5 and the interface structures we show that the energy-displacement curve can be well described by including extra polynomial terms in the Universal Binding Energy Relation (UBER). It is shown that the Fe2Al5//Fe interface has a higher tensile strength than the bulk Fe2Al5 phase. We also find that the shear deformation process potentially can be initiated from an Fe-terminated interface.

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Research paper thumbnail of First-principles study of tensile and shear strength of Fe-Al and α-AlFeSi intermetallic compound interfaces

First-principles virtual tensile and shear strength calculations have been performed on the Fe2Al... more First-principles virtual tensile and shear strength calculations have been performed on the Fe2Al5// Fe4Al13 and -AlFeSi// Fe4Al13 interfaces. The Fast Inertial Relaxation Engine (FIRE) algorithm is used for optimizing these complex Intermetallic Compound (IMC) interface structures. To characterize the virtual tensile strength, an extended generalized Universal Binding Energy Relation (UBER) was used to fit the energy-displacement data. The virtual tensile strength was evaluated with the Rigid Grain Shift (RGS) methodology without atomic relaxations during tensile displacement and with RGS+relaxation with atomic relaxations. All calculated values for IMC//IMC interfaces in this study are compared with pure Al//Fe and Al//IMCs [1] interfaces to identify the role of IMCs at aluminum-steel joints.

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Research paper thumbnail of Ab-initio study of atomic structure and mechanical behaviour of Al Fe / intermetallic interfaces

Computational Materials Science, 2020

First-principles virtual tensile and shear test calculations have been performed to Al(0 03 ¯)//-... more First-principles virtual tensile and shear test calculations have been performed to Al(0 03 ¯)//-AlFeSi(0 0 1) and Al(01 ¯ 4)//Fe 4 Al 13 (1 01 ¯) interfaces by the ab initio pseudo potential density functional theory method. Work of separation, ultimate tensile strength and shear strength of bulk and interface structures were calculated. The Al (0 03 ¯)/-AlFeSi(0 0 1) interface showed higher tensile strength than the Al(01 ¯ 4)//Fe 4 Al 13 (1 01 ¯) interface structure. Moreover, interface calculations revealed a charge depletion region in the second layer of the Fe 4 Al 13 structure, which caused lower work of separation. Furthermore, shear calculations showed stronger shear strength for the Al(01 ¯ 4)//Fe 4 Al 13 (1 01 ¯) interface than for the Al(0 0 1)//-AlFeSi(0 0 1) interface structure.

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Research paper thumbnail of DFT calculations based insight into bonding character and strength of Fe2Al5 and Fe4Al13 intermetallics at Al-Fe joints

The joining of aluminum and steel has been considered as the efficient combination to develop lig... more The joining of aluminum and steel has been considered as the efficient combination to develop lightweight and environmental friendly structures. However, due to the significant differences in mechanical and physical properties of aluminum and steel, the joining of these two metals is challenging, where typically several intermetallic phases are formed at the interface. Origin of intermetallic phases at the Al-Fe interface is inevitable due to the low intermixing of Al and Fe. Thus in order to achieve reliable joining, it is necessary to have basic understanding about these intermetallic phases. This paper aims to describe mechanical and bonding properties of the two most commonly observed phases, Fe4Al13 and Fe2Al5. The formation energy, elastic properties and nature of bonding of Fe4Al13 and Fe2Al5 have been calculated. The results show that Fe2Al5 is thermodynamically more stable than Fe4Al13, and it seems to be less brittle than Fe4Al13. Electron localization plots of these compounds show a combination of covalent and metallic bonding, where Fe4Al13 shows a stronger tendency of covalent character than Fe2Al5.

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Research paper thumbnail of Mechanism of Laser/light beam interaction at cellular and tissue level and study of the influential factors for the application of low level laser therapy

After the discovery of laser therapy it was realized it has useful application of wound healing a... more After the discovery of laser therapy it was realized it has useful application of wound healing and reduce pain, but due to the poor understanding of the mechanism and dose response this technique remained to be controversial for therapeutic applications. In order to understand the working and effectiveness different experiments were performed to determine the laser beam effect at the cellular and tissue level. This article discusses the mechanism of beam interaction at tissues and cellular level with different light sources and dosimetry principles for clinical application of low level laser therapy. Different application techniques and methods currently in use for clinical treatment has also been reviewed.

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Research paper thumbnail of A Novel Method for Analytical Solution of Transient Heat Conduction and Stefan Problem in Cylindrical Coordinate

It has been found numerical methods are very tiring and time consuming and so much dependent upon... more It has been found numerical methods are very tiring and time consuming and so much dependent upon computational calculations, so in order to reduce the computational time a new eigenfunction expansion method is presented for a two dimensional case with heat generation source. This method is applicable to any combination of inhomogeneous first and second kind boundary conditions in the angular and axial direction of cylinder and can be very useful for latent heat energy based storage systems analytical analysis. Analytical problem of one phase melting/solidification of Phase Change Material was also studied with the use of dimensionless parameters using the eigenfunction expansion method. Effect of Dimensionless parameter Stefan number on the melting/solidification of PCM was studied. Results showed increase in the transition time at low Stefan value.

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Conference Presentations by Muhammad Zeeshan Khalid

Research paper thumbnail of Forced and Natural Convection Modeling for Phase Change Problem

The current economic and technological advancement has increased the load of energy sources, many... more The current economic and technological advancement has increased the load of energy sources, many conventional energy sources are quite limited and have much hazardous effect on the health of living beings and environment of our earth, besides this emission of Green House Gas is considered the main cause of environmental changes. In view of these problems a need of an efficient and clean energy source through the use of advanced technologies and systems are fostering day by day. For this purpose Different types of solar power plant are now being used to convert solar energy into electricity production unit. Limited availability of sunlight forces the use of Thermal energy storage unit for the production of electricity throughout the day.

Phase Change Materials (PCMs) is one of the most basic and important component of TES unit for storage and retrieval of heat. PCMs store heat by absorbing heat from Heat Transfer fluid of solar plant by phase transition (Solid-Liquid). Liquid PCM then release heat during discharging process which is being absorbed by HTF and forwarded to power generation unit to generate electricity. Many researchers used numerical techniques to study the performance of Thermal energy storage unit (e.g 4, 5) but there is not much work on the analytical modeling of TES unit to study the forced and natural convection. Recently Bechiri[1] modeled one tube and shell mode to study the melting and thermal energy storage capacity of the system using analytical technique. Results obtained showed good agreement with numerical and experimental data. This goal of this project is to model a system involving Heat transfer fluid as a heat source and Phase Change Material contained in a cylindrical container to study the effects of convection on the transition rate of material. Analytical method was applied to simulate results and different dimensionless parameters such as Biot number and Rayleigh number was introduced to study forced and natural convection.

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Research paper thumbnail of Ab-initio study of atomic structure and mechanical behaviour of Al/Fe intermetallic interfaces

Computational Materials Science, 2020

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Research paper thumbnail of Modified embedded atom method potential for Fe-Al intermetallics mechanical strength: A comparative analysis of atomistic simulations

Physica B-condensed Matter, 2021

The structural and mechanical properties of Fe-Al compounds (FeAl, Fe 2 Al, Fe 3 Al, FeAl 2 , FeA... more The structural and mechanical properties of Fe-Al compounds (FeAl, Fe 2 Al, Fe 3 Al, FeAl 2 , FeAl 3 , Fe 2 Al 5 ) have been studied using modified embedded atom method (MEAM) potentials. The equilibrium lattice constants, formation enthalpies, and elastic properties have been investigated and compared with other studies. The calculated lattice constants show good agreement with the embedded atom method (EAM) and density functional theory (DFT) calculations and with experiments. All Fe-Al compounds are mechanically stable according to the elastic constants restrictions. The calculated bulk modulus of the compounds does not show a linear relation with Fe concentration, which is most probably caused by the mechanical anisotropy of Fe-Al compounds. However, comparison of the Fe-Al mechanical properties of MEAM, DFT and EAM-based approaches and experiments show non-consistent differences, which reflects uncertainties with several of these methods, due to assumptions and simplifications ...

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Research paper thumbnail of Modified embedded atom method potential for Fe-Al intermetallics mechanical strength: A comparative analysis of atomistic simulations

Physica B: Physics of Condensed Matter, 2021

The structural and mechanical properties of Fe-Al compounds (FeAl, Fe2Al, Fe3Al, FeAl2, FeAl3, Fe... more The structural and mechanical properties of Fe-Al compounds (FeAl, Fe2Al, Fe3Al, FeAl2, FeAl3, Fe2Al5) have been studied using modified embedded atom method (MEAM) potentials. The equilibrium lattice constants, formation enthalpies, and elastic properties have been investigated and compared with other studies. The calculated lattice constants show good agreement with the embedded atom method (EAM) and density functional theory (DFT) calculations and with experiments. All Fe-Al compounds are mechanically stable according to the elastic constants restrictions. The calculated bulk modulus of the compounds does not show a linear relation with Fe concentration, which is most probably caused by the mechanical anisotropy of Fe-Al compounds. However, comparison of the Fe-Al mechanical properties of MEAM, DFT and EAM-based approaches and experiments show non-consistent differences, which reflects uncertainties with several of these methods, due to assumptions and simplifications imposed during calculations. In general, DFT calculations are closer to experimental observations than semi-empirical potentials. Comprehensive comparisons are made based on theoretical and experimental methodologies.

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Research paper thumbnail of First-principles study of tensile and shear strength of an Fe 2 Al 5 // Fe interface

The interfacial strengths of a low misfit Fe2Al5//Fe interface structure found at aluminum-steel ... more The interfacial strengths of a low misfit Fe2Al5//Fe interface structure found at aluminum-steel joints has been studied using density functional theory. An interface between Fe and Fe2Al5 was selected based on a criteria of low lattice misfit and number of atoms. Through virtual tensile testing of bulk Fe2Al5 and the interface structures we show that the energy-displacement curve can be well described by including extra polynomial terms in the Universal Binding Energy Relation (UBER). It is shown that the Fe2Al5//Fe interface has a higher tensile strength than the bulk Fe2Al5 phase. We also find that the shear deformation process potentially can be initiated from an Fe-terminated interface.

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Research paper thumbnail of First-principles study of tensile and shear strength of Fe-Al and α-AlFeSi intermetallic compound interfaces

First-principles virtual tensile and shear strength calculations have been performed on the Fe2Al... more First-principles virtual tensile and shear strength calculations have been performed on the Fe2Al5// Fe4Al13 and -AlFeSi// Fe4Al13 interfaces. The Fast Inertial Relaxation Engine (FIRE) algorithm is used for optimizing these complex Intermetallic Compound (IMC) interface structures. To characterize the virtual tensile strength, an extended generalized Universal Binding Energy Relation (UBER) was used to fit the energy-displacement data. The virtual tensile strength was evaluated with the Rigid Grain Shift (RGS) methodology without atomic relaxations during tensile displacement and with RGS+relaxation with atomic relaxations. All calculated values for IMC//IMC interfaces in this study are compared with pure Al//Fe and Al//IMCs [1] interfaces to identify the role of IMCs at aluminum-steel joints.

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Research paper thumbnail of Ab-initio study of atomic structure and mechanical behaviour of Al Fe / intermetallic interfaces

Computational Materials Science, 2020

First-principles virtual tensile and shear test calculations have been performed to Al(0 03 ¯)//-... more First-principles virtual tensile and shear test calculations have been performed to Al(0 03 ¯)//-AlFeSi(0 0 1) and Al(01 ¯ 4)//Fe 4 Al 13 (1 01 ¯) interfaces by the ab initio pseudo potential density functional theory method. Work of separation, ultimate tensile strength and shear strength of bulk and interface structures were calculated. The Al (0 03 ¯)/-AlFeSi(0 0 1) interface showed higher tensile strength than the Al(01 ¯ 4)//Fe 4 Al 13 (1 01 ¯) interface structure. Moreover, interface calculations revealed a charge depletion region in the second layer of the Fe 4 Al 13 structure, which caused lower work of separation. Furthermore, shear calculations showed stronger shear strength for the Al(01 ¯ 4)//Fe 4 Al 13 (1 01 ¯) interface than for the Al(0 0 1)//-AlFeSi(0 0 1) interface structure.

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Research paper thumbnail of DFT calculations based insight into bonding character and strength of Fe2Al5 and Fe4Al13 intermetallics at Al-Fe joints

The joining of aluminum and steel has been considered as the efficient combination to develop lig... more The joining of aluminum and steel has been considered as the efficient combination to develop lightweight and environmental friendly structures. However, due to the significant differences in mechanical and physical properties of aluminum and steel, the joining of these two metals is challenging, where typically several intermetallic phases are formed at the interface. Origin of intermetallic phases at the Al-Fe interface is inevitable due to the low intermixing of Al and Fe. Thus in order to achieve reliable joining, it is necessary to have basic understanding about these intermetallic phases. This paper aims to describe mechanical and bonding properties of the two most commonly observed phases, Fe4Al13 and Fe2Al5. The formation energy, elastic properties and nature of bonding of Fe4Al13 and Fe2Al5 have been calculated. The results show that Fe2Al5 is thermodynamically more stable than Fe4Al13, and it seems to be less brittle than Fe4Al13. Electron localization plots of these compounds show a combination of covalent and metallic bonding, where Fe4Al13 shows a stronger tendency of covalent character than Fe2Al5.

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Research paper thumbnail of Mechanism of Laser/light beam interaction at cellular and tissue level and study of the influential factors for the application of low level laser therapy

After the discovery of laser therapy it was realized it has useful application of wound healing a... more After the discovery of laser therapy it was realized it has useful application of wound healing and reduce pain, but due to the poor understanding of the mechanism and dose response this technique remained to be controversial for therapeutic applications. In order to understand the working and effectiveness different experiments were performed to determine the laser beam effect at the cellular and tissue level. This article discusses the mechanism of beam interaction at tissues and cellular level with different light sources and dosimetry principles for clinical application of low level laser therapy. Different application techniques and methods currently in use for clinical treatment has also been reviewed.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Novel Method for Analytical Solution of Transient Heat Conduction and Stefan Problem in Cylindrical Coordinate

It has been found numerical methods are very tiring and time consuming and so much dependent upon... more It has been found numerical methods are very tiring and time consuming and so much dependent upon computational calculations, so in order to reduce the computational time a new eigenfunction expansion method is presented for a two dimensional case with heat generation source. This method is applicable to any combination of inhomogeneous first and second kind boundary conditions in the angular and axial direction of cylinder and can be very useful for latent heat energy based storage systems analytical analysis. Analytical problem of one phase melting/solidification of Phase Change Material was also studied with the use of dimensionless parameters using the eigenfunction expansion method. Effect of Dimensionless parameter Stefan number on the melting/solidification of PCM was studied. Results showed increase in the transition time at low Stefan value.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Forced and Natural Convection Modeling for Phase Change Problem

The current economic and technological advancement has increased the load of energy sources, many... more The current economic and technological advancement has increased the load of energy sources, many conventional energy sources are quite limited and have much hazardous effect on the health of living beings and environment of our earth, besides this emission of Green House Gas is considered the main cause of environmental changes. In view of these problems a need of an efficient and clean energy source through the use of advanced technologies and systems are fostering day by day. For this purpose Different types of solar power plant are now being used to convert solar energy into electricity production unit. Limited availability of sunlight forces the use of Thermal energy storage unit for the production of electricity throughout the day.

Phase Change Materials (PCMs) is one of the most basic and important component of TES unit for storage and retrieval of heat. PCMs store heat by absorbing heat from Heat Transfer fluid of solar plant by phase transition (Solid-Liquid). Liquid PCM then release heat during discharging process which is being absorbed by HTF and forwarded to power generation unit to generate electricity. Many researchers used numerical techniques to study the performance of Thermal energy storage unit (e.g 4, 5) but there is not much work on the analytical modeling of TES unit to study the forced and natural convection. Recently Bechiri[1] modeled one tube and shell mode to study the melting and thermal energy storage capacity of the system using analytical technique. Results obtained showed good agreement with numerical and experimental data. This goal of this project is to model a system involving Heat transfer fluid as a heat source and Phase Change Material contained in a cylindrical container to study the effects of convection on the transition rate of material. Analytical method was applied to simulate results and different dimensionless parameters such as Biot number and Rayleigh number was introduced to study forced and natural convection.

Bookmarks Related papers MentionsView impact