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Masahiro Kubota - One of the best experts on this subject based on the ideXlab platform.
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Solid-state reaction in mechanically milled and spark plasma sintered Al–B4C composite materials
Journal of Alloys and Compounds, 2010Co-Authors: Masahiro KubotaAbstract:Abstract Air-atomised pure aluminium powder with additions of 12.5 at%, 37.5 at% and 62.5 at% of B 4 C was mechanically alloyed (MAed) by using a vibrational ball mill, and MAed powders were consolidated into bulk materials by a spark plasma sintering (SPS) Process. Solid-state reactions of the MAed powders during heat treatments were examined by X-ray diffraction (XRD), and mechanical properties of the MAed powder obtained under various heat treatment conditions and those of the SPS materials were evaluated by hardness tests. The solid-state reactions occurred among pure aluminium, B 4 C and stearic acid, added as a Process Control Agent (PCA), after heating at 673 K to 873 K for 24 h to form AlB10, Al3BC and γ-Al2O3. The products obtained by solid-state reactions have affected the Vickers microhardness of the heat-treated MAed powders. The near full density was obtained for the SPS materials under the conditions of an applied pressure of 49 MPa at 873 K for 1 h. The Al–12.5B 4 C SPS material from 16 h MAed powder exhibited the highest hardness value of 210 HV in the as-fabricated state.
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Mechanically Alloyed and Spark Plasma Sintered Aluminium/Precious Metal Oxide Composite Materials
Materials Science Forum, 2010Co-Authors: Masahiro Kubota, Pavel CizekAbstract:Air-atomised pure aluminium powder with additions of 10 at.% of AgO, PtO2 or PdO was mechanically alloyed (MAed) by using a vibrational ball mill, and MAed powders were consolidated into bulk materials by a spark plasma sintering (SPS) Process. Mechano-chemical reactions among pure Al, precious metal oxide and stearic acid, added as a Process Control Agent, during the mechanical alloying (MA) Process and subsequent heat treatments were investigated by X-ray diffraction. The mechanical properties of MAed powders obtained under various heat treatment conditions and those of the SPS materials were evaluated by hardness tests. Mechano-chemical reactions occurred in Al/precious metal oxide composite powders during 36 ks of the MA Process to form AlAg2, Pt and Al3Pd2 for the Al-AgO, Al-PtO2 and Al-PdO systems, respectively. Further solid-state reactions in MAed powders have been observed after heating at 373 K to 873 K for 7.2 ks. The hardness of MAed powders initially increased significantly after heating at 373 K and then generally decreased with increasing heating temperatures. The full density was obtained for the SPS materials under the conditions of an applied pressure of 49 MPa at 873 K for 3.6 ks. All the SPS materials exhibited hardness values of over 200 HV in the as-fabricated state.
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properties of nano structured pure al produced by mechanical grinding and spark plasma sintering
Journal of Alloys and Compounds, 2007Co-Authors: Masahiro KubotaAbstract:Abstract Air-atomised pure aluminium powder was mechanically grinded (MG) using a vibrational ball mill, and mechanically grinded powder was sintered by spark plasma sintering (SPS). Solid-state reactions of MG powder after various heat treatments were studied by X-ray diffraction (XRD). The mechanical properties of the SPS materials were evaluated by hardness and compression testing. Characterisations of the solid-state reactions between the MG powder and Process Control Agent (PCA) after heating at temperatures from 573 to 873 K for 24 h suggested the following products. No solid-state reaction was observed after heating up to 573 K for 24 h. Formation of γ-Al 2 O 3 occurred in the 4 h MG powder after heating at 773 K for 24 h, whereas the mixture of γ-Al 2 O 3 and Al 4 C 3 was observed in the 8 h MG powder after heating at 773 K for 24 h. The full density of the SPS material was obtained with the condition of applied pressure at 49 MPa at 873 K for 1 h. The Vickers hardness of the SPS material produced from no MG Process and 64 h MG powders exhibited HV39 and HV159, respectively, and the SPS material based on no MG Process and 8 h MG powders showed room temperature compressive proof stresses of 173 and 440 MPa, respectively.
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Synthesis of Al3BC from mechanically milled and spark plasma sintered Al–MgB2 composite materials
Journal of Alloys and Compounds, 2007Co-Authors: Masahiro Kubota, Pavel CizekAbstract:Abstract The aluminium-rich ternary aluminium borocarbide, Al 3 BC was synthesised for the first time by solid-state reactions occurring during heat treatments after mechanical milling (MM) of pure aluminium with 15 or 50 at% MgB 2 powder mixtures in the presence of the Process Control Agent (PCA). The solid-state reactions in the Al–15 and 50 at% MgB 2 composite materials occurred between the MMed powders and Process Control Agent (PCA) after heating at 773–873 K for 24 h. The products of the solid-state reaction induced Al 3 BC, AlB 2 , γ-Al 2 O 3 and spinel MgAl 2 O 4 . MM Processing time and heating temperatures in the Al–15 and 50 at% MgB 2 composite materials affected the selection of those intermetallic compounds. When MM Processing time was increased for a given composition, the formation of the Al 3 BC compound started at lower heat treatment temperatures. However, when the amount of MgB 2 was increased in the 4 h MM Processing regime, the formation of the Al 3 BC compound during heating was suppressed. As a result of the solid-state reactions in MMed powders the hardness was observed to increase after heating at 573–873 K for 24 h. The fully dense bulk nano-composite materials have been successfully obtained through the combination of the MM and spark plasma sintering (SPS) Processes for the 4 h or 8 h MMed powders of the Al–15 at% MgB 2 composite materials sintered under an applied pressure of 49 MPa at 873 K for 1 h.
Cuie Wen - One of the best experts on this subject based on the ideXlab platform.
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role of Process Control Agent in the synthesis of multi walled carbon nanotubes reinforced titanium metal matrix powder mixtures
Advanced Engineering Materials, 2016Co-Authors: Khurram Munir, Daniel T. Oldfield, Cuie WenAbstract:The present study investigates the influence of Process Control Agent (PCA), i.e., stearic acid (SA) on the dispersion of multi-walled carbon nanotubes (MWCNT) into the titanium (Ti) matrix during mechanical alloying. A planetary ball mill was used in dispersing 0.5wt.% MWCNT into the Ti matrix. The powder mixtures were prepared in two batches: without and with the addition of 0.5wt.% SA. Green compacts of high energy ball milled powder mixtures were consolidated by using a uniaxial hydraulic press. Raman spectroscopy combined with X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the powder mixtures and green compacts. The evolution of MWCNT has been discussed in conjunction with the formation of nano crystalline TiC in the ball milled powder mixtures.
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Role of Process Control Agent in the Synthesis of Multi‐Walled Carbon Nanotubes Reinforced Titanium Metal Matrix Powder Mixtures
Advanced Engineering Materials, 2015Co-Authors: Khurram Munir, Daniel T. Oldfield, Cuie WenAbstract:The present study investigates the influence of Process Control Agent (PCA), i.e., stearic acid (SA) on the dispersion of multi-walled carbon nanotubes (MWCNT) into the titanium (Ti) matrix during mechanical alloying. A planetary ball mill was used in dispersing 0.5wt.% MWCNT into the Ti matrix. The powder mixtures were prepared in two batches: without and with the addition of 0.5wt.% SA. Green compacts of high energy ball milled powder mixtures were consolidated by using a uniaxial hydraulic press. Raman spectroscopy combined with X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the powder mixtures and green compacts. The evolution of MWCNT has been discussed in conjunction with the formation of nano crystalline TiC in the ball milled powder mixtures.
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Effect of Process Control Agent on the porous structure and mechanical properties of a biomedical Ti-Sn-Nb alloy produced by powder metallurgy
Acta Biomaterialia, 2010Co-Authors: Alireza Nouri, Peter Hodgson, Cuie WenAbstract:Abstract The influence of different amounts and types of Process Control Agent (PCA), i.e., stearic acid and ethylene bis-stearamide, on the porous structure and mechanical properties of a biomedical Ti–16Sn–4Nb (wt.%) alloy was investigated. Alloy synthesis was performed on elemental metal powders using high-energy ball milling for 5 h. Results indicated that varying the PCA content during ball milling led to a drastic change in morphology and particle-size distribution of the ball-milled powders. Porous titanium alloy samples sintered from the powders ball milled with the addition of various amounts of PCA also revealed different pore morphology and porosity. The Vickers hardness of the sintered titanium alloy samples exhibited a considerable increase with increasing PCA content. Moreover, the addition of larger amounts of PCA in the powder mixture resulted in a significant increase in the elastic modulus and peak stress for the sintered porous titanium alloy samples under compression. It should also be mentioned that the addition of PCA introduced contamination (mainly carbon and oxygen) into the sintered porous product.
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Effects of Process Control Agent on the microstructure and mechanical properties of Ti-Sn-Nb alloy prepared by mechanical alloying
2008Co-Authors: Alireza Nouri, Yasuo Yamada, Peter Hodgson, Cuie WenAbstract:In the present study, the influence of Process Control Agent (PCA) on the characteristics of powder and bulk sintered Ti-16Sn-4Nb (wt. %) alloy prepared by mechanical alloying has been investigated. The elemental Ti, Sn and Nb powders were mechanically alloyed in a planetary ball mill for a short period of time using two types of PCA, namely stearic acid (SA) and ethylene bis-stearamide (EBS). The powder morphology, microstructural evolution of the bulk sintered alloy, phase formation and hardness of the alloy have been studied as a function of PCA. Results indicated that the addition of PCA leads to a delay in aIloy formation and introduces contaminations (mainly carbon and oxygen) into the material. The microstructural observation of the bulk alloy revealed a homogeneous distribution of fine Nb-rich colonies (s-phase) within the a-Ti matrix for small amount of PCA. The hardness values of samples exhibited a significant increase with increasing amount of PCA, reaching a value of ~ 600 BV.
Silethelwe Chikosha - One of the best experts on this subject based on the ideXlab platform.
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Effect of Process Control Agent (PCA) on the characteristics of mechanically alloyed Ti-Mg powders [Journal article]
2011Co-Authors: Christopher N Machio, Hilda Chikwanda, Silethelwe ChikoshaAbstract:Copyright: 2011 Southern African Institute of Mining and Metallurgy. This paper was first presented at the, Light Metals Conference, 27–29 October 2010, Misty Hills, Muldersdrift.
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Effect of Process Control Agent (PCA) on the characteristics of mechanically alloyed Ti-Mg powders
Journal of The South African Institute of Mining and Metallurgy, 2011Co-Authors: Christopher N Machio, Hilda Chikwanda, Silethelwe ChikoshaAbstract:Synopsis This paper reports the results of a study to determine the effect of Process Control Agent (PCA) on the characteristics of Ti-Mg powders during milling. It has been shown that a 2% increase in PCA content leads to up to a 40% increase in yield of the milled powder but reduces the kinetics of the mechanical alloying Process. The
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Effect of Process Control Agent (PCA) on the characteristics of mechanically alloyed Ti-Mg powders [Conference paper]
2010Co-Authors: Christopher N Machio, Hilda Chikwanda, Silethelwe ChikoshaAbstract:The Southern African Institute of Mining and Metallurgy Advanced Metals Initiative Light Metals Conference 2010, Misty Hills, Muldersdrift, 27–29 October 2010
Christopher N Machio - One of the best experts on this subject based on the ideXlab platform.
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Effect of Process Control Agent (PCA) on the characteristics of mechanically alloyed Ti-Mg powders [Journal article]
2011Co-Authors: Christopher N Machio, Hilda Chikwanda, Silethelwe ChikoshaAbstract:Copyright: 2011 Southern African Institute of Mining and Metallurgy. This paper was first presented at the, Light Metals Conference, 27–29 October 2010, Misty Hills, Muldersdrift.
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Effect of Process Control Agent (PCA) on the characteristics of mechanically alloyed Ti-Mg powders
Journal of The South African Institute of Mining and Metallurgy, 2011Co-Authors: Christopher N Machio, Hilda Chikwanda, Silethelwe ChikoshaAbstract:Synopsis This paper reports the results of a study to determine the effect of Process Control Agent (PCA) on the characteristics of Ti-Mg powders during milling. It has been shown that a 2% increase in PCA content leads to up to a 40% increase in yield of the milled powder but reduces the kinetics of the mechanical alloying Process. The
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Characterization of mechanically alloyed f.c.c. Ti–Mg-based powders
Powder Technology, 2010Co-Authors: Christopher N Machio, D. Nyabadza, V. Sibanda, Hilda ChikwandaAbstract:Abstract Face centred cubic Ti–10 and 20Mg and Ti–6Al–4Mg (wt.%) alloy powders have been produced by high energy ball milling, under argon, of elemental powder mixtures containing a Process Control Agent (PCA). Milling leads to a multi-disperse particle size distribution without affecting the particle morphologies. This affects the thermal stability of the powders and the green densities of compacts. The green densities varied in tandem with the d 10 sizes of the powders and went through a minimum at 20 h of milling. Milling for 20 h could be detrimental to powder consolidation and further Processing.
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Effect of Process Control Agent (PCA) on the characteristics of mechanically alloyed Ti-Mg powders [Conference paper]
2010Co-Authors: Christopher N Machio, Hilda Chikwanda, Silethelwe ChikoshaAbstract:The Southern African Institute of Mining and Metallurgy Advanced Metals Initiative Light Metals Conference 2010, Misty Hills, Muldersdrift, 27–29 October 2010
Alireza Nouri - One of the best experts on this subject based on the ideXlab platform.
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Study on the Role of Stearic Acid and Ethylene-bis-stearamide on the Mechanical Alloying of a Biomedical Titanium Based Alloy
Metallurgical and Materials Transactions A, 2010Co-Authors: Alireza Nouri, Peter D. HodgsonAbstract:The present study examines the influence of different contents and types of Process Control Agent (PCA), i.e. , stearic acid (SA) and ethylene-bis-stearamide (EBS), on the microstructural evolution and characteristics of Ti-16Sn-4Nb (wt pct) alloy powders and bulk samples. The characterization of the powders and bulk samples was carried out by using chemical analysis, optical microscopy, scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS), and X-ray diffractometry. Results indicated that the powder recovered from the ball milling containers increased with increasing amounts of SA and EBS. Furthermore, adding more SA or EBS to the powder mixture resulted in a considerably smaller particle size, with a flaky-shaped morphology for the given ball milling time. Also, a slightly higher effectiveness was found for EBS when compared to SA. Meanwhile, the addition of both SA and EBS led to a delay in the alloy formation during mechanical alloying (MA) and caused contamination of the material with mainly carbon (C) and oxygen (O). An optimum amount of 1 wt pct PCA led to a good balance between cold welding and fracturing, and thus favored the formation of the titanium alloy. The microstructural observation of the bulk alloy showed a homogeneous distribution of fine Nb-rich β -phase colonies within the α -Ti matrix with the addition of PCA less than 1 wt pct.
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Effect of Process Control Agent on the porous structure and mechanical properties of a biomedical Ti-Sn-Nb alloy produced by powder metallurgy
Acta Biomaterialia, 2010Co-Authors: Alireza Nouri, Peter Hodgson, Cuie WenAbstract:Abstract The influence of different amounts and types of Process Control Agent (PCA), i.e., stearic acid and ethylene bis-stearamide, on the porous structure and mechanical properties of a biomedical Ti–16Sn–4Nb (wt.%) alloy was investigated. Alloy synthesis was performed on elemental metal powders using high-energy ball milling for 5 h. Results indicated that varying the PCA content during ball milling led to a drastic change in morphology and particle-size distribution of the ball-milled powders. Porous titanium alloy samples sintered from the powders ball milled with the addition of various amounts of PCA also revealed different pore morphology and porosity. The Vickers hardness of the sintered titanium alloy samples exhibited a considerable increase with increasing PCA content. Moreover, the addition of larger amounts of PCA in the powder mixture resulted in a significant increase in the elastic modulus and peak stress for the sintered porous titanium alloy samples under compression. It should also be mentioned that the addition of PCA introduced contamination (mainly carbon and oxygen) into the sintered porous product.
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Effects of Process Control Agent on the microstructure and mechanical properties of Ti-Sn-Nb alloy prepared by mechanical alloying
2008Co-Authors: Alireza Nouri, Yasuo Yamada, Peter Hodgson, Cuie WenAbstract:In the present study, the influence of Process Control Agent (PCA) on the characteristics of powder and bulk sintered Ti-16Sn-4Nb (wt. %) alloy prepared by mechanical alloying has been investigated. The elemental Ti, Sn and Nb powders were mechanically alloyed in a planetary ball mill for a short period of time using two types of PCA, namely stearic acid (SA) and ethylene bis-stearamide (EBS). The powder morphology, microstructural evolution of the bulk sintered alloy, phase formation and hardness of the alloy have been studied as a function of PCA. Results indicated that the addition of PCA leads to a delay in aIloy formation and introduces contaminations (mainly carbon and oxygen) into the material. The microstructural observation of the bulk alloy revealed a homogeneous distribution of fine Nb-rich colonies (s-phase) within the a-Ti matrix for small amount of PCA. The hardness values of samples exhibited a significant increase with increasing amount of PCA, reaching a value of ~ 600 BV.