Mahmoud Soliman | King Saud University (original) (raw)

Papers by Mahmoud Soliman

Advanced Materials Research, 2012

ABSTRACT

Scripta Metallurgica et Materialia

When a superplastic metal is deformed at high temperatures, the steady-state rate, ~, is describe... more When a superplastic metal is deformed at high temperatures, the steady-state rate, ~, is described by the equation = Aa '~ d -p exp (-Q/nT) (1)

Scripta Metallurgica et Materialia

ABSTRACT

International Journal of Materials and Product Technology

ABSTRACT

SABIC Hadeed Company in Saudi Arabia has introduced a new technology (bar quenching) to its rolli... more SABIC Hadeed Company in Saudi Arabia has introduced a new technology (bar quenching) to its rolling mills in Jubail, for the manufacture of superior quality concrete reinforcing bars. This technology uses the state of the art process involving high pressure surface quenching followed by self-tempering. As the bars emerge from the last rolling stand, the surface temperature is rapidly reduced by high-pressure water jets. This action causes change in the structure, making it harder and stronger. The production of this type of bars is so large that it has been decided to market it for some other purposes such as machining. Since no or little machining data are available for cutting SABIC structural steel, a machining database for SABIC structural steel is to be established. Also, the machining parameters of SABIC structural steels are to be optimized to enhance machinability.

The present study was undertaken to investigate the role of matrix composition (pure Al versus ex... more The present study was undertaken to investigate the role of matrix composition (pure Al versus experimental 6063 alloy) and heat treatment conditions on the tensile properties, and fracture behavior of Zr and Ti-containing Al-15vol% B 4 C metal matrix composites. While addition of transition elements such as Zr, Sc and Ti to Al alloys is known to enhance their high temperature performance, in the case of composites, the presence of the reinforcement may alter the strengthening kinetics in the composite material due to reinforcement/matrix interactions, which could affect or hinder the properties otherwise expected from the matrix alloy. The study therefore focused on (1) a complete characterization of these composites and (2) an evaluation of their performance at elevated temperatures. Tensile tests performed on aged Metal Matrix Composites (MMCs) show that Zr (with or without Ti) resulted in a noticeable hardening due to the precipitation of Zr-rich phase. Precipitation of Zr-Ti compounds during aging contributed to the composite strength. Maximum strengthening was obtained from the 6063-based MMC due to the precipitation of Mg 2 Si phase particles. The addition of Zr and Ti resulted in the formation of protective layers around the B 4 C particles that were retained after fracture. The B 4 C fractured transgranularly without debonding from the matrix. Stacking faults were commonly observed in fractured Al 6063/B 4 C/15p composite samples.

Two base alloys of Al-15 vol.% B4C and 6063-15 vol.% B4C metal matrix composites (MMCs) were prod... more Two base alloys of Al-15 vol.% B4C and 6063-15 vol.% B4C metal matrix composites (MMCs) were produced using a powder injection technique. Alloying additions of 0.5wt.% Ti, 0.35wt.% Zr and 0.35wt.% Sc were made to the base alloys to produce various compositions of the two MMCs. For the purpose of investigating the effect of reinforcement/matrix (B4C/Al) interaction on the composite toughness, ten compositions of pure Al-15 vol.% B4C and 6063-15 vol.% B4C with various additions of Ti, Zr and Sc were produced. A metallic L-shaped mould was used for casting the aluminum MMCs. Reinforcement/matrix interface interactions in the produced composites were investigated as a function of the alloying elements added using field emission gun scanning electron microscopy (FEGSEM) and energy dispersive x-ray (EDX) techniques. The results show that the toughness of a given composite is controlled by the type of heat treatment and amount of added elements or refractory materials. Introduction of Ti alone leads to reaction with some of the B4C particles, converting them to Al-Ti-B or Al-Ti-C compounds. The addition of Zr reacts with Ti forming Al3(Ti,Zr) which minimizes the particle/matrix interaction. Repeated remelting of the composite coupled with a high stirring speed may cause fragmentation of the B4C particles.

Composites Part B: Engineering, 2015

The present work was performed on ten metal matrix composites (MMCs) produced using the new powde... more The present work was performed on ten metal matrix composites (MMCs) produced using the new powder injection technique. These MMCs were divided into two series in which pure aluminum was the matrix for one series, while an experimental 6063 alloy was the matrix for the second series. Small amounts of Ti, Zr and Sc were added to those composites, either individually or combined. In all cases the volume fraction of the reinforced B 4 C particles was in the range 12e15 vol. %. The molten metal was cast in an L-shaped metallic mold preheated at 350 C. Unnotched rectangular impact samples (1 cm  1 cm  5 cm) were prepared from these castings and heat treated. Samples were tested using instrumental impact testing machine. Microstructure and fracture surface were examined using Hitachi SU-8000 FESEM. The results show that the presence of Ti improves the wettability of the B 4 C particles and their adherence to the matrix. Repeated remelting at 730 C applying vigorous mechanical stirring could lead to fragmentation of some of the B 4 C particles. Aluminum based composites exhibited better toughness compared to those obtained from 6063 based composites in all the studied conditions. The composite impact toughness was controlled by the precipitation and coarsening of hardening phase particles namely Mg 2 Si, Al 3 Zr and/or Al 3 Sc. Cracks in the fracture surface were observed to be initiated at the particle/matrix interfaces and propagate either through the B 4 C particles or through the protective layers. No complete debonding was reported due the presence of Zr/Ti/Sc rich layers which improved the particle/matrix adhesion.

Materials Science and Engineering, 1985

Creep tests were conducted on A1-Mg alloys at very low stresses, where newtonian behavior of the ... more Creep tests were conducted on A1-Mg alloys at very low stresses, where newtonian behavior of the Harper-Dorn type was previously reported, under the condition of large creep strains. The creep curves obtained show the presence of large transient strains before steady state is reached. This finding indicates that the earlier creep data on these alloys obtained from short-term tests (strains less than 1%) are not representative of steady state creep.

Materials Science and Engineering, 1982

... 111 - 119 111 Correlation Between Creep Behavior and Substructure in an A1-3at.%Mg Solid Solu... more ... 111 - 119 111 Correlation Between Creep Behavior and Substructure in an A1-3at.%Mg Solid Solution Alloy MAHMOUD S. SOLIMAN and FARGHALLI A ... It has been suggested that the creep deformation of a solid solution alloy may be 0025-5416/82/0000-0000/$02.75 Elsevier ...

IOP Conference Series: Materials Science and Engineering, 2014

ABSTRACT Mechanical Attrition of metallic powders induces severe plastic deformation and conseque... more ABSTRACT Mechanical Attrition of metallic powders induces severe plastic deformation and consequently reduces the average grain size. Powders of 99.7 Al (45μm particle size), cryomilled for 7 hrs having a crystal size of ~ 20 nm, were consolidated by high frequency induction sintering under a constant pressure of 50 MPa and at two temperatures of 500 and 550 °C for two sintering dwell times of 1 and 3 minutes at a constant heating rate of 400 °C/min. The bright field TEM image and X-ray line broadening technique, for the cryomilled powders, were used to measure-the crystallite size. Simple compression at an initial strain rate of 10−4 s−1 was conducted at room temperature, 373 and 473 K, and the yield strength was documented and correlated with the sintering parameters. The as-received 99.7 Al powders-consolidated using one of the sintering parameters was used as a reference material to compare the mechanical properties. Hardness, density and crystal size of the consolidated sample, that gave the highest yield and fracture strength, were measured.

Materials Sciences and Applications, 2011

The effect of OH − concentration on the morphology of the hydroxyapatite (HA) nanorod synthesized... more The effect of OH − concentration on the morphology of the hydroxyapatite (HA) nanorod synthesized using electrophoretic deposition (EPD) method has been investigated. The growth of HA nanorods was achieved on polished titanium substrates. The electrolyte used in this study was prepared by dissolving calcium acetate (Ca (CH 3 COO) 2 H 2 O), and Ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) in distilled water without any surfactant, and was maintained at 80-130˚C. Two electrolytes with OH − concentration of 10 −4 and 10 −10 were prepared. A highly homogeneous HA nanorods deposited on the titanium substrates were obtained after 1 h in the electrolytes with higher OH − concentration of 10 −4 . On the other hand, a flower-shaped HA nanostructures composed of needle-like HA crystals were obtained in the electrolyte of lower OH − concentration of 10 −10 . The deposits were identified as HA crystal rods grown along the c axis and perpendicular to the substrate. The HA deposits were characterized by scanning electron microscopy (SEM) while detailed structural characterization was done using a transmission electron microscope (TEM) equipped with selected area electron diffraction (SAED) patterns.

... Mahmoud S. Soliman 1,a , Ehab A. EL-Danaf 1,b and Abdulhakim A. Almajid 1,c,d ... 83-86 (2010... more ... Mahmoud S. Soliman 1,a , Ehab A. EL-Danaf 1,b and Abdulhakim A. Almajid 1,c,d ... 83-86 (2010) pp 407-414 Online available since 2009/Dec/21 at www.scientific.net © (2010) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.83-86.407 ...

Non-ferrous metals and alloys Mechanical properties of materials Plastic behavior a b s t r a c t

ABSTRACT In the present investigation, annealed billets of commercially pure Al (1050) with coars... more ABSTRACT In the present investigation, annealed billets of commercially pure Al (1050) with coarse-grained microstructure of 0.6 mm were ECAPed through a die with an internal angle of 90o using two routes A and BC. The samples were processed up to four passes using both routes. The change in the processing route results in the change of the shear plane, and consequently the change in the produced microstructure. The microstructure study was conducted on the extrusion direction and the shear plane. The cell size, misoriention and the fraction of high angle boundaries were determined by using electron back scattered diffraction (EBSD). A study of mechanical behavior was conducted by cutting tensile and compression specimens from the ECAPed specimen in the extrusion direction to study the effect of processing route and the number of passes on the deformation characteristics. Enhanced strength was observed but with anisotropic behavior between tension and compression. Cyclic deformation under load control (HSF) was also performed and the S-N curves were established as a function of number of passes and processing route. The fractography of fractured tensile specimens was also investigated.

Materials & Design, 2012

An eutectic lead -tin alloy was casted in the form of cylindrical billets that were machined down... more An eutectic lead -tin alloy was casted in the form of cylindrical billets that were machined down, and then processed in a 90°equal channel angular pressing (ECAP) die, via route C to four passes. Evaluation of the microstructure was done via optical and scanning electron microscopy. This process resulted in dynamically recrystallized a + b structure of interphase boundary size of $6 lm. Tensile testing was performed at different initial strain rates at three temperatures of 25 (room temperature), 50 and 75°C. The steady state true stresses were depicted and plotted against the respective strain rates. A constant strain rate sensitivity parameter m of 0.44 was observed at the three testing temperatures. The high value of m, the activation energy along with large elongation percent suggest the operation of grain boundary sliding as rate controlling process. The value of elongation percent (ductility) was also depicted and plotted as a function of strain rate at various temperatures. It was noticed that, the ductility values at each temperature attain a maximum value and this maximum value increases and shifts to high strain rates with increasing temperature.

Nanocrystalline 6061 Al alloy was synthesized by cryogenic milling (cryomilling). Both transmissi... more Nanocrystalline 6061 Al alloy was synthesized by cryogenic milling (cryomilling). Both transmission electron microscopy and X-ray diffraction were used to monitor the change in grain size as a function of milling time. The results of both techniques demonstrated a close agreement with respect to two observations: (a) during cryomilling, the grain size of 6061 Al decreased with milling time, and (b) after 15 h of milling, the grain size approached a minimum value of about 22 nm. Despite this agreement, there was a discrepancy: for grain sizes > 40 nm, the grain size measured by transmission electron microscopy was appreciably larger than that inferred from X-ray diffraction. It was shown that powders consolidated via high frequency induction heat sintering (HFIHS) at 500 and 550 ∘ C maintained close to nanoscale grain sized microstructure in addition to high compact density in bulk samples. This was manifested by high strength values as compared to microscale grain samples.

Advanced Materials Research, 2012

ABSTRACT

Scripta Metallurgica et Materialia

When a superplastic metal is deformed at high temperatures, the steady-state rate, ~, is describe... more When a superplastic metal is deformed at high temperatures, the steady-state rate, ~, is described by the equation = Aa '~ d -p exp (-Q/nT) (1)

Scripta Metallurgica et Materialia

ABSTRACT

International Journal of Materials and Product Technology

ABSTRACT

SABIC Hadeed Company in Saudi Arabia has introduced a new technology (bar quenching) to its rolli... more SABIC Hadeed Company in Saudi Arabia has introduced a new technology (bar quenching) to its rolling mills in Jubail, for the manufacture of superior quality concrete reinforcing bars. This technology uses the state of the art process involving high pressure surface quenching followed by self-tempering. As the bars emerge from the last rolling stand, the surface temperature is rapidly reduced by high-pressure water jets. This action causes change in the structure, making it harder and stronger. The production of this type of bars is so large that it has been decided to market it for some other purposes such as machining. Since no or little machining data are available for cutting SABIC structural steel, a machining database for SABIC structural steel is to be established. Also, the machining parameters of SABIC structural steels are to be optimized to enhance machinability.

The present study was undertaken to investigate the role of matrix composition (pure Al versus ex... more The present study was undertaken to investigate the role of matrix composition (pure Al versus experimental 6063 alloy) and heat treatment conditions on the tensile properties, and fracture behavior of Zr and Ti-containing Al-15vol% B 4 C metal matrix composites. While addition of transition elements such as Zr, Sc and Ti to Al alloys is known to enhance their high temperature performance, in the case of composites, the presence of the reinforcement may alter the strengthening kinetics in the composite material due to reinforcement/matrix interactions, which could affect or hinder the properties otherwise expected from the matrix alloy. The study therefore focused on (1) a complete characterization of these composites and (2) an evaluation of their performance at elevated temperatures. Tensile tests performed on aged Metal Matrix Composites (MMCs) show that Zr (with or without Ti) resulted in a noticeable hardening due to the precipitation of Zr-rich phase. Precipitation of Zr-Ti compounds during aging contributed to the composite strength. Maximum strengthening was obtained from the 6063-based MMC due to the precipitation of Mg 2 Si phase particles. The addition of Zr and Ti resulted in the formation of protective layers around the B 4 C particles that were retained after fracture. The B 4 C fractured transgranularly without debonding from the matrix. Stacking faults were commonly observed in fractured Al 6063/B 4 C/15p composite samples.

Two base alloys of Al-15 vol.% B4C and 6063-15 vol.% B4C metal matrix composites (MMCs) were prod... more Two base alloys of Al-15 vol.% B4C and 6063-15 vol.% B4C metal matrix composites (MMCs) were produced using a powder injection technique. Alloying additions of 0.5wt.% Ti, 0.35wt.% Zr and 0.35wt.% Sc were made to the base alloys to produce various compositions of the two MMCs. For the purpose of investigating the effect of reinforcement/matrix (B4C/Al) interaction on the composite toughness, ten compositions of pure Al-15 vol.% B4C and 6063-15 vol.% B4C with various additions of Ti, Zr and Sc were produced. A metallic L-shaped mould was used for casting the aluminum MMCs. Reinforcement/matrix interface interactions in the produced composites were investigated as a function of the alloying elements added using field emission gun scanning electron microscopy (FEGSEM) and energy dispersive x-ray (EDX) techniques. The results show that the toughness of a given composite is controlled by the type of heat treatment and amount of added elements or refractory materials. Introduction of Ti alone leads to reaction with some of the B4C particles, converting them to Al-Ti-B or Al-Ti-C compounds. The addition of Zr reacts with Ti forming Al3(Ti,Zr) which minimizes the particle/matrix interaction. Repeated remelting of the composite coupled with a high stirring speed may cause fragmentation of the B4C particles.

Composites Part B: Engineering, 2015

The present work was performed on ten metal matrix composites (MMCs) produced using the new powde... more The present work was performed on ten metal matrix composites (MMCs) produced using the new powder injection technique. These MMCs were divided into two series in which pure aluminum was the matrix for one series, while an experimental 6063 alloy was the matrix for the second series. Small amounts of Ti, Zr and Sc were added to those composites, either individually or combined. In all cases the volume fraction of the reinforced B 4 C particles was in the range 12e15 vol. %. The molten metal was cast in an L-shaped metallic mold preheated at 350 C. Unnotched rectangular impact samples (1 cm  1 cm  5 cm) were prepared from these castings and heat treated. Samples were tested using instrumental impact testing machine. Microstructure and fracture surface were examined using Hitachi SU-8000 FESEM. The results show that the presence of Ti improves the wettability of the B 4 C particles and their adherence to the matrix. Repeated remelting at 730 C applying vigorous mechanical stirring could lead to fragmentation of some of the B 4 C particles. Aluminum based composites exhibited better toughness compared to those obtained from 6063 based composites in all the studied conditions. The composite impact toughness was controlled by the precipitation and coarsening of hardening phase particles namely Mg 2 Si, Al 3 Zr and/or Al 3 Sc. Cracks in the fracture surface were observed to be initiated at the particle/matrix interfaces and propagate either through the B 4 C particles or through the protective layers. No complete debonding was reported due the presence of Zr/Ti/Sc rich layers which improved the particle/matrix adhesion.

Materials Science and Engineering, 1985

Creep tests were conducted on A1-Mg alloys at very low stresses, where newtonian behavior of the ... more Creep tests were conducted on A1-Mg alloys at very low stresses, where newtonian behavior of the Harper-Dorn type was previously reported, under the condition of large creep strains. The creep curves obtained show the presence of large transient strains before steady state is reached. This finding indicates that the earlier creep data on these alloys obtained from short-term tests (strains less than 1%) are not representative of steady state creep.

Materials Science and Engineering, 1982

... 111 - 119 111 Correlation Between Creep Behavior and Substructure in an A1-3at.%Mg Solid Solu... more ... 111 - 119 111 Correlation Between Creep Behavior and Substructure in an A1-3at.%Mg Solid Solution Alloy MAHMOUD S. SOLIMAN and FARGHALLI A ... It has been suggested that the creep deformation of a solid solution alloy may be 0025-5416/82/0000-0000/$02.75 Elsevier ...

IOP Conference Series: Materials Science and Engineering, 2014

ABSTRACT Mechanical Attrition of metallic powders induces severe plastic deformation and conseque... more ABSTRACT Mechanical Attrition of metallic powders induces severe plastic deformation and consequently reduces the average grain size. Powders of 99.7 Al (45μm particle size), cryomilled for 7 hrs having a crystal size of ~ 20 nm, were consolidated by high frequency induction sintering under a constant pressure of 50 MPa and at two temperatures of 500 and 550 °C for two sintering dwell times of 1 and 3 minutes at a constant heating rate of 400 °C/min. The bright field TEM image and X-ray line broadening technique, for the cryomilled powders, were used to measure-the crystallite size. Simple compression at an initial strain rate of 10−4 s−1 was conducted at room temperature, 373 and 473 K, and the yield strength was documented and correlated with the sintering parameters. The as-received 99.7 Al powders-consolidated using one of the sintering parameters was used as a reference material to compare the mechanical properties. Hardness, density and crystal size of the consolidated sample, that gave the highest yield and fracture strength, were measured.

Materials Sciences and Applications, 2011

The effect of OH − concentration on the morphology of the hydroxyapatite (HA) nanorod synthesized... more The effect of OH − concentration on the morphology of the hydroxyapatite (HA) nanorod synthesized using electrophoretic deposition (EPD) method has been investigated. The growth of HA nanorods was achieved on polished titanium substrates. The electrolyte used in this study was prepared by dissolving calcium acetate (Ca (CH 3 COO) 2 H 2 O), and Ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) in distilled water without any surfactant, and was maintained at 80-130˚C. Two electrolytes with OH − concentration of 10 −4 and 10 −10 were prepared. A highly homogeneous HA nanorods deposited on the titanium substrates were obtained after 1 h in the electrolytes with higher OH − concentration of 10 −4 . On the other hand, a flower-shaped HA nanostructures composed of needle-like HA crystals were obtained in the electrolyte of lower OH − concentration of 10 −10 . The deposits were identified as HA crystal rods grown along the c axis and perpendicular to the substrate. The HA deposits were characterized by scanning electron microscopy (SEM) while detailed structural characterization was done using a transmission electron microscope (TEM) equipped with selected area electron diffraction (SAED) patterns.

... Mahmoud S. Soliman 1,a , Ehab A. EL-Danaf 1,b and Abdulhakim A. Almajid 1,c,d ... 83-86 (2010... more ... Mahmoud S. Soliman 1,a , Ehab A. EL-Danaf 1,b and Abdulhakim A. Almajid 1,c,d ... 83-86 (2010) pp 407-414 Online available since 2009/Dec/21 at www.scientific.net © (2010) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.83-86.407 ...

Non-ferrous metals and alloys Mechanical properties of materials Plastic behavior a b s t r a c t

ABSTRACT In the present investigation, annealed billets of commercially pure Al (1050) with coars... more ABSTRACT In the present investigation, annealed billets of commercially pure Al (1050) with coarse-grained microstructure of 0.6 mm were ECAPed through a die with an internal angle of 90o using two routes A and BC. The samples were processed up to four passes using both routes. The change in the processing route results in the change of the shear plane, and consequently the change in the produced microstructure. The microstructure study was conducted on the extrusion direction and the shear plane. The cell size, misoriention and the fraction of high angle boundaries were determined by using electron back scattered diffraction (EBSD). A study of mechanical behavior was conducted by cutting tensile and compression specimens from the ECAPed specimen in the extrusion direction to study the effect of processing route and the number of passes on the deformation characteristics. Enhanced strength was observed but with anisotropic behavior between tension and compression. Cyclic deformation under load control (HSF) was also performed and the S-N curves were established as a function of number of passes and processing route. The fractography of fractured tensile specimens was also investigated.

Materials & Design, 2012

An eutectic lead -tin alloy was casted in the form of cylindrical billets that were machined down... more An eutectic lead -tin alloy was casted in the form of cylindrical billets that were machined down, and then processed in a 90°equal channel angular pressing (ECAP) die, via route C to four passes. Evaluation of the microstructure was done via optical and scanning electron microscopy. This process resulted in dynamically recrystallized a + b structure of interphase boundary size of $6 lm. Tensile testing was performed at different initial strain rates at three temperatures of 25 (room temperature), 50 and 75°C. The steady state true stresses were depicted and plotted against the respective strain rates. A constant strain rate sensitivity parameter m of 0.44 was observed at the three testing temperatures. The high value of m, the activation energy along with large elongation percent suggest the operation of grain boundary sliding as rate controlling process. The value of elongation percent (ductility) was also depicted and plotted as a function of strain rate at various temperatures. It was noticed that, the ductility values at each temperature attain a maximum value and this maximum value increases and shifts to high strain rates with increasing temperature.

Nanocrystalline 6061 Al alloy was synthesized by cryogenic milling (cryomilling). Both transmissi... more Nanocrystalline 6061 Al alloy was synthesized by cryogenic milling (cryomilling). Both transmission electron microscopy and X-ray diffraction were used to monitor the change in grain size as a function of milling time. The results of both techniques demonstrated a close agreement with respect to two observations: (a) during cryomilling, the grain size of 6061 Al decreased with milling time, and (b) after 15 h of milling, the grain size approached a minimum value of about 22 nm. Despite this agreement, there was a discrepancy: for grain sizes > 40 nm, the grain size measured by transmission electron microscopy was appreciably larger than that inferred from X-ray diffraction. It was shown that powders consolidated via high frequency induction heat sintering (HFIHS) at 500 and 550 ∘ C maintained close to nanoscale grain sized microstructure in addition to high compact density in bulk samples. This was manifested by high strength values as compared to microscale grain samples.