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D P Bishop - One of the best experts on this subject based on the ideXlab platform.
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industrial processing of a novel al cu Mg Powder metallurgy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: C D Boland, R L Hexemer, Ian W Donaldson, D P BishopAbstract:Abstract The objective of this work was to develop an aluminum Powder metallurgy (P/M) alloy appropriate for industrial press-sinter technology. An entry in the 2 xxx series of aluminum–copper–magnesium alloys was explored for this purpose. Designated as P/M 2324 (Al–4.4Cu–1.5Mg), the sintering response and mechanical properties of the alloy were investigated in laboratory and industrial settings. It was determined that compaction at 400 MPa and sintering at 600 °C for 20 min produced the best properties in the sintered product. Doping with a minor amount of tin (0.2w/o) was found to improve the properties whereas modifications to Cu and Mg concentration produced minimal gains. All tensile properties of P/M 2324 were significantly superior to those of the principal 2 xxx series aluminum P/M alloy (AC2014) in current use. These benefits were attributed to a high sintered density (>98% theoretical) that was reproducible in an industrial setting.
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hot deformation of an al cu Mg Powder metallurgy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: R E D Mann, R L Hexemer, Ian W Donaldson, D P BishopAbstract:The effort to improve automobile efficiency has potential economic and environmental advantages. The field of aluminum Powder metallurgy (P/M) is of particular interest as the implementation of such technologies to produce parts can offer the combination of a weight savings and the economic advantages of near net shape processing. However, one of the hurdles to overcome in the field of P/M is the presence of porosity in the sintered product. To reduce the presence of this attribute, sintered materials can be hot forged to full density. In this study, the forging response of a novel aluminum–copper–magnesium P/M alloy, P/M 2324, was studied in comparison to its wrought counterpart AA2024. Modelling of the peak flow stress required in the P/M and wrought alloys yielded very similar results with both materials adhering to a standard Zener–Hollomon curve fitting approach. Rotary swaging was also completed to assess the impact of hot work on the P/M material. These findings confirmed that full density could be achieved in P/M 2324 and that the concomitant tensile properties were significantly higher for the swaged P/M system. Microstructurally, it appeared that the principal secondary phase in P/M 2324 was θ (Al2Cu) whereas the S phase (Al2MgCu) was pronounced in the wrought system.
Mauro Alini - One of the best experts on this subject based on the ideXlab platform.
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osteogenic magnesium incorporated into plga tcp porous scaffold by 3d printing for repairing challenging bone defect
Biomaterials, 2019Co-Authors: Yu Xiao Lai, Xin Luan Wang, David Eglin, Tingting Tang, Jiang Peng, Huijuan Cao, Jing Long, Qingyun Jia, Bin Teng, Mauro AliniAbstract:Bone defect repair is a challenging clinical problem in musculoskeletal system, especially in orthopaedic disorders such as steroid associated osteonecrosis (SAON). Magnesium (Mg) as a biodegradable metal with properly mechanical properties has been investigating for a long history. In this study, Mg Powder, poly (lactide-co-glycolide) (PLGA), β-tricalcium phosphate (β-TCP) were the elements to formulate a novel porous PLGA/TCP/Mg (PTM) scaffolds using low temperature rapid prototyping (LT-RP) technology. The physical characterization of PTM scaffold and Mg ions release were analyzed in vitro. The osteogenic and angiogenic properties of PTM scaffolds, as well as the biosafety after implantation were assessed in an established SAON rabbit model. Our results showed that the PTM scaffold possessed well-designed bio-mimic structure and improved mechanical properties. Findings of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and micro-computed tomography (micro CT)-based angiography indicated that PTM scaffold could increase blood perfusion and promote new vessel ingrowth at 4 weeks after surgery, meanwhile, a plenty of newly formed vessels with well-architective structure were observed at 8 weeks. Correspondingly, at 12 weeks after surgery, micro-CT, histological and mechanical properties analysis showed that PTM could significant enhance new bone formation and strengthen newly formed bone mechanical properties. The mean bone volume in PTM group was 56.3% greater than that in PT group. Biosafety assessments from 0 to 12 weeks after implantation did not induce increase in serum Mg ions concentration, and immune response, liver and kidney function parameters were all at normal level. These findings suggested that the PTM scaffold had both osteogenic and angiogenic abilities which were synergistic effect in enhancing new bone formation and strengthen newly formed bone quality in SAON. In summary, PTM scaffolds are promising composite biomaterials for repairing challenging bone defect that would have great potential for its clinical translation.
James W Rawlins - One of the best experts on this subject based on the ideXlab platform.
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magnesium based sacrificial anode cathodic protection coatings Mg rich primers for aluminum alloys
Metals, 2012Co-Authors: Shashi S Pathak, Sharathkumar K Mendon, Michael D Blanton, James W RawlinsAbstract:Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg Powder is now employed in organic coatings (termed as Mg-rich primers) as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD) to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.
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carbonation of Mg Powder to enhance the corrosion resistance of Mg rich primers
Corrosion Science, 2010Co-Authors: S S Pathak, Sharathkumar K Mendon, Michael D Blanton, James W RawlinsAbstract:Abstract This paper is a continuation of our investigation into the characteristic dichotomy of Mg-rich primers between accelerated salt-fog testing and natural weathering. Our earlier study suggested that magnesium Powder reacted with atmospheric CO2 to form a protective carbonate layer on its surface. In this study, magnesium Powder was treated with aqueous carbonic acid to accelerate magnesium carbonate development. The treated magnesium Powder was formulated into a Mg-rich primer and evaluated for its corrosion resistance. The Mg-rich primer formulated with the treated Mg Powder performed better in the salt-fog test than the control primer based on untreated Mg Powder.
Xiaoyan Zeng - One of the best experts on this subject based on the ideXlab platform.
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selective laser melting of high strength al cu Mg alloys processing microstructure and mechanical properties
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Hu Zhang, Haihong Zhu, Ting Qi, Zhiheng Hu, Xiaoyan ZengAbstract:Abstract The interest for a wider range of usable materials for the technology of selective laser melting (SLM) is growing. In this work, the manufacturing of wrought Al–Cu–Mg parts using SLM technology was systematically investigated. The effect of processing parameters on the density of the deposited Al–Cu–Mg samples was studied. It shows that the laser energy density plays a significant role in the densification behavior of the Al–Cu–Mg Powder during the SLM process. The laser energy density value of 340 J/mm 3 is found to be the threshold, above which high density samples (99.8%) without imperfections and microcracks can be obtained. The SLMed Al–Cu–Mg part presents a unique layer-wise feature which consisted of an extremely fine supersaturated cellular-dendrites structure. The ultimate tensile strength of 402 MPa and the yield strength of 276 MPa are achieved for the SLMed Al–Cu–Mg part. The combination of grain refinement and solid solution strengthening mechanisms during SLM process are proposed to explain the high mechanical strength.
Ian W Donaldson - One of the best experts on this subject based on the ideXlab platform.
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industrial processing of a novel al cu Mg Powder metallurgy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: C D Boland, R L Hexemer, Ian W Donaldson, D P BishopAbstract:Abstract The objective of this work was to develop an aluminum Powder metallurgy (P/M) alloy appropriate for industrial press-sinter technology. An entry in the 2 xxx series of aluminum–copper–magnesium alloys was explored for this purpose. Designated as P/M 2324 (Al–4.4Cu–1.5Mg), the sintering response and mechanical properties of the alloy were investigated in laboratory and industrial settings. It was determined that compaction at 400 MPa and sintering at 600 °C for 20 min produced the best properties in the sintered product. Doping with a minor amount of tin (0.2w/o) was found to improve the properties whereas modifications to Cu and Mg concentration produced minimal gains. All tensile properties of P/M 2324 were significantly superior to those of the principal 2 xxx series aluminum P/M alloy (AC2014) in current use. These benefits were attributed to a high sintered density (>98% theoretical) that was reproducible in an industrial setting.
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hot deformation of an al cu Mg Powder metallurgy alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: R E D Mann, R L Hexemer, Ian W Donaldson, D P BishopAbstract:The effort to improve automobile efficiency has potential economic and environmental advantages. The field of aluminum Powder metallurgy (P/M) is of particular interest as the implementation of such technologies to produce parts can offer the combination of a weight savings and the economic advantages of near net shape processing. However, one of the hurdles to overcome in the field of P/M is the presence of porosity in the sintered product. To reduce the presence of this attribute, sintered materials can be hot forged to full density. In this study, the forging response of a novel aluminum–copper–magnesium P/M alloy, P/M 2324, was studied in comparison to its wrought counterpart AA2024. Modelling of the peak flow stress required in the P/M and wrought alloys yielded very similar results with both materials adhering to a standard Zener–Hollomon curve fitting approach. Rotary swaging was also completed to assess the impact of hot work on the P/M material. These findings confirmed that full density could be achieved in P/M 2324 and that the concomitant tensile properties were significantly higher for the swaged P/M system. Microstructurally, it appeared that the principal secondary phase in P/M 2324 was θ (Al2Cu) whereas the S phase (Al2MgCu) was pronounced in the wrought system.