The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Sung Hyuk Park - One of the best experts on this subject based on the ideXlab platform.
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significant improvement in Extrudability of mg 9al 0 8zn 0 9ca 0 6y alloy through mischmetal addition
Metals and Materials International, 2021Co-Authors: Hyun Ji Kim, Byoung Gi Moon, Jonghun Yoon, Sanghoon Kim, Sangwon Lee, Youngmin Kim, Jeong Hun Lee, Sung Hyuk ParkAbstract:The combined addition of small amounts of Ca and Y to Mg–Al–Zn alloys has recently been found to greatly improve the ignition resistance, corrosion resistance, and mechanical properties of these alloys. However, Mg–Al–Zn–Ca–Y alloys with high Al content show poor Extrudability, which is an obstacle to their use as extruded components in industrial applications. This study aims to improve the Extrudability of a Mg–Al–Zn–Ca–Y alloy through the addition of a small amount of mischmetal (MM). To this end, a trace amount (0.5 wt%) of Ce-rich MM is added to a Mg–9Al–0.8Zn–0.9Ca–0.6Y (AZXW9110) alloy. MM addition leads to significant grain refinement of the homogenized billet, from 326 to 180 μm. When the MM-added alloy is extruded into a sheet at 350 °C with an extrusion ratio of 22.9, the maximum ram speed at which it is extrudable without the occurrence of hot cracking is 12 mm/s, substantially higher than the 2 mm/s possible without MM addition. The Ce and La atoms decomposed from the MM are dissolved in the Mg17Al12, Al8Mn4Y, Al2Ca, and Al2Y phases, apparently leading to an increase in the thermal stability of the phases and, consequently, to an improvement in the AZXW9110 alloy’s Extrudability. At ram speeds above 2 mm/s, many small-sized cracks form at the edges of the extruded AZXW9110–0.5MM sheets. As the ram speed increases up to 6 mm/s, the number density of edge cracks gradually increases while their average spacing decreases, but beyond 6 mm/s both remain almost unchanged.
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novel mg bi al alloy with extraordinary Extrudability and high strength
Journal of Alloys and Compounds, 2020Co-Authors: Sangcheol Jin, Hyun Ji Kim, Sung Hyuk ParkAbstract:Abstract A novel high-alloyed Mg–5Bi–3Al (BA53, wt%) alloy with extraordinary Extrudability and high strength is developed. It is successfully extruded at a die-exit speed of 67 m/min without any hot cracking, which is over 10 times the maximum extrusion speeds of commercial high-alloyed Mg alloys, e.g., AZ80 and ZK60. The BA53 alloy extruded at 67 m/min shows high tensile yield strengths in the as-extruded and peak-aged states (188 and 214 MPa, respectively). These excellent Extrudability and high strength are mainly attributed to the formation of thermally stable Mg3Bi2 phase. Undissolved coarse and fine Mg3Bi2 particles effectively suppress grain growth during and after extrusion through grain-boundary pinning, leading to the formation of a relatively fine grain structure. Fine rod-type Mg3Bi2 precipitates formed on the prismatic plane along the Mg direction during air-cooling after existing the die lead to precipitation hardening. The formation of numerous nanosized Mg3Bi2 precipitates along the 0 1 ¯ 10 >Mg direction during subsequent aging improves the material strength without ductility loss. The developed BA53 alloy, which comprises inexpensive alloying elements Bi and Al, can be extensively used for manufacturing extruded Mg products because of its high cost-competitiveness, processing efficiency, and mechanical properties.
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Improvement in Extrudability and mechanical properties of AZ91 alloy through extrusion with artificial cooling
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Byoung Gi Moon, Sung Hyuk ParkAbstract:Abstract This study demonstrates that the application of artificial water cooling during extrusion effectively increases the Extrudability of the AZ91 alloy and significantly improves the mechanical properties of the extruded AZ91 alloy. The artificial cooling dramatically reduces the actual temperature of the deformation zone, which results in an increase in the maximum exit speed at which the alloy is extrudable without the occurrence of hot cracking from 4.5 m/min to 7.5 m/min. It also promotes dynamic recrystallization and precipitation behaviors during extrusion, which leads to a reduction in grain size and an increase in the amount of fine Mg 17 Al 12 precipitates. As a result, for the AZ91 alloy extruded at an exit speed of 1.5 m/min, the tensile and compressive yield strengths improve significantly by 51 MPa and 114 MPa, respectively, and its tension–compression yield asymmetry reduces from 0.73 to 1.02 owing to the refinement of the grain size by artificial cooling. In addition, the AZ91 alloy extruded at an exit speed of 7.5 m/min with artificial cooling exhibits a finer grain structure than and superior mechanical properties to the AZ91 alloy extruded at a slower exit speed of 4.5 m/min without artificial cooling. This result indicates that the application of artificial cooling can simultaneously improve the maximum extrusion speed and the tensile and compressive properties of Mg alloys.
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high speed indirect extrusion of mg sn al zn alloy and its influence on microstructure and mechanical properties
Journal of Alloys and Compounds, 2016Co-Authors: Sung Hyuk Park, Jonghun YoonAbstract:Abstract This investigation into the effect of indirectly extruding Mg–7Sn–1Al–1Zn (TAZ711) alloy at high exit speeds on the microstructure and tensile properties found no evidence of surface cracking, not even at the maximum speed tested of 27 m/min. This high-speed Extrudability is attributed to the relatively high incipient melting temperature of the alloy (535 °C), which results from the formation of a thermally stable Mg 2 Sn phase. All extruded samples exhibited a completely recrystallized (DRXed) structure consisting of coarse DRXed grains with few particles in combination with relatively fine DRXed grains containing numerous fine precipitates. With an increase in extrusion speed, the total amount of Mg 2 Sn precipitates decreased and the size and quantity of coarse DRXed grains increased due to a rise in temperature during extrusion. This has the effect of reducing the strength of the extruded alloy through a reduction in precipitation and grain-boundary strengthening, yet the elongation of the extruded alloy remains essentially the same due to a loss of ductility caused by the increase in DRXed grain size.
Shigeharu Kamado - One of the best experts on this subject based on the ideXlab platform.
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rare earth texture and improved ductility in a mg zn gd alloy after high speed extrusion
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: M G Jiang, T Nakata, Hong Yan, Rongshi Chen, Shigeharu KamadoAbstract:Abstract Mg-1.58Zn-0.52Gd (wt%) alloy was successfully extruded at high extrusion speed of 60 m/min, suggesting the much better Extrudability than commercial AZ31 alloy. After high-speed extrusion (die-exit speed ≥24 m/min), the Mg-Zn-Gd alloy exhibited a fully recrystallized microstructure with fine Mg3Zn3Gd2 phase at grain boundaries (GBs) and within grain interiors and rare earth (RE) texture at the position between [2 1 1 4] and [2 1 1 2] parallel to the extrusion direction. The RE texture favored the operation of both basal slip and {10 1 2} extension twins, thus leading to a highly improved ductility of ∼30%, which was twice than that of the AZ31 alloy. It is hypothesized that the segregation of Gd solutes at GBs greatly influences the recrystallization behavior and thus contributes to the formation of RE texture.
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high speed extrusion of heat treatable mg al ca mn dilute alloy
Scripta Materialia, 2015Co-Authors: T Nakata, T Mezaki, R Ajima, C Xu, K Ohishi, K Shimizu, Satoru Hanaki, Takayoshi Sasaki, K Hono, Shigeharu KamadoAbstract:Abstract A newly developed dilute magnesium alloy, Mg–0.27Al–0.13Ca–0.21Mn (at.%), shows extraordinary high-speed Extrudability of a die-exit speed of 60 m/min. Subsequent artificial aging at 200 °C (T5) enhanced the proof stress from 170 MPa to 207 MPa due to the precipitation of Guinier Preston (G.P.) zones and weakened basal texture while keeping good ductility of 12.5%. High-speed extrusion reduces the processing cost, so the dilute Mg–Al–Ca–Mn alloy could be an industrially viable low-cost medium strength structural material.
Ming Jen Tan - One of the best experts on this subject based on the ideXlab platform.
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feasibility study on sustainable magnesium potassium phosphate cement paste for 3d printing
Construction and Building Materials, 2019Co-Authors: Yiwei Weng, Ming Jen Tan, Shaoqin Ruan, Mingyang Li, Liwu Mo, Cise Unluer, Shunzhi QianAbstract:Abstract 3D printing of cementitious materials is an innovative and promising approach in the construction sector, attracting much attention over the past few years. Use of waste cementitious materials in the production of 3D printable components increases the sustainability and cost-effectiveness of this process. This work proposes an environmentally friendly 3D printable cementitious material involving the use of magnesium potassium phosphate cement (MKPC) with various ratios of fly ash replacement ranging from 0 to 60 wt% to increase the working time of the binder. Silica fume was used at up to 10 wt% to adjust rheological and mechanical properties. The performance of the developed MKPC binders with different formulations in the context of 3D printing was assessed via a detailed investigation of the workability, Extrudability, buildability, compressive strength, porosity and microstructural analysis. Amongst the mixtures studied, the optimum MKPC formulation involving 60 wt% fly ash and 10 wt% silica fume with a borax-to-magnesia ratio of 1:4 was selected for a small-scale printing demonstration in line with its rheological and mechanical properties. Finally, a 20-layer component with a height of 180 mm was printed in 5 min to demonstrate the feasibility of the adopted mixture in 3D printing.
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experimental study on mix proportion and fresh properties of fly ash based geopolymer for 3d concrete printing
Ceramics International, 2018Co-Authors: Biranchi Panda, Ming Jen TanAbstract:Abstract This paper presents the material design and fresh properties of geopolymer mortar developed for 3D concrete printing application. Unlike traditional casting, in 3D printing, extruded materials are deposited layer-by-layer to build complex architectural and structural components without the need of any formwork and human intervention. Extrudability, shape retention, buildability and thixotropic open time (TOT) are identified as critical early-age properties to characterize the 3D printable geopolymer material. Five different mix designs of geopolymer are tested in a systematic experimental approach to obtain a best printable mix and later it is used to print a 60-centimeter-tall freeform structure using a concrete gantry printer to validate the formulation.
T Nakata - One of the best experts on this subject based on the ideXlab platform.
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rare earth texture and improved ductility in a mg zn gd alloy after high speed extrusion
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: M G Jiang, T Nakata, Hong Yan, Rongshi Chen, Shigeharu KamadoAbstract:Abstract Mg-1.58Zn-0.52Gd (wt%) alloy was successfully extruded at high extrusion speed of 60 m/min, suggesting the much better Extrudability than commercial AZ31 alloy. After high-speed extrusion (die-exit speed ≥24 m/min), the Mg-Zn-Gd alloy exhibited a fully recrystallized microstructure with fine Mg3Zn3Gd2 phase at grain boundaries (GBs) and within grain interiors and rare earth (RE) texture at the position between [2 1 1 4] and [2 1 1 2] parallel to the extrusion direction. The RE texture favored the operation of both basal slip and {10 1 2} extension twins, thus leading to a highly improved ductility of ∼30%, which was twice than that of the AZ31 alloy. It is hypothesized that the segregation of Gd solutes at GBs greatly influences the recrystallization behavior and thus contributes to the formation of RE texture.
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high speed extrusion of heat treatable mg al ca mn dilute alloy
Scripta Materialia, 2015Co-Authors: T Nakata, T Mezaki, R Ajima, C Xu, K Ohishi, K Shimizu, Satoru Hanaki, Takayoshi Sasaki, K Hono, Shigeharu KamadoAbstract:Abstract A newly developed dilute magnesium alloy, Mg–0.27Al–0.13Ca–0.21Mn (at.%), shows extraordinary high-speed Extrudability of a die-exit speed of 60 m/min. Subsequent artificial aging at 200 °C (T5) enhanced the proof stress from 170 MPa to 207 MPa due to the precipitation of Guinier Preston (G.P.) zones and weakened basal texture while keeping good ductility of 12.5%. High-speed extrusion reduces the processing cost, so the dilute Mg–Al–Ca–Mn alloy could be an industrially viable low-cost medium strength structural material.
L O Gullman - One of the best experts on this subject based on the ideXlab platform.
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microstructure control and Extrudability of al mg si alloys microalloyed with manganese
Materials Science and Technology, 1994Co-Authors: Stanislaw Zajac, Bevis Hutchinson, A Johansson, L O GullmanAbstract:AbstractThe hot deformation of AA 6063 and AA 6005 Al alloys has been related to chemical composition and the microstructural evolution occurring during the various heat treatment procedures before extrusion. It was shown that a small addition of Mn significantly accelerates the homogenising process (transformation of the brittle platelike β-AlFeSi phase to the more rounded α-AlFeSi phase) which results in superior hot formability and ductility. The mechanical behaviour of Al–Mg–Si alloys during hot deformation can be explained in terms of a model of dislocations climbing around particles. Large β phase particles increase initial work hardening rate and flow stress and impair hot ductility. The hot ductility of the material investigated via tensile testing was found to correlate with the density of particles covering grain boundaries. It was also shown that grain refinement in the billet leads to more uniform distribution of intermetallic constituents, which accelerates the homogenising process and improv...
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microstructure control and Extrudability of aluminium mg si alloys microalloyed with manganese
Journal De Physique Iv, 1993Co-Authors: Stanislaw Zajac, Bevis Hutchinson, A Johansson, L O Gullman, Rune LagneborgAbstract:The hot deformation behaviour of AA 6063 and AA 6005 aluminium alloys has been related to chemical composition and the microstructural evolution occurring during the various heat treatment procedures prior to extrusion. It was shown that a small addition of manganese significance homogenising process (transformation of the plate-like beta-AlFeSi phase to the more rounded alpha-AlFeSi phase) which gives better hot formability and ductility. The mechanical behaviour of Al-Mg-Si alloys during hot working at low and intermediate strains was described by a new model for the accumulation and annihilation by climb of geometrically necessary dislocations at non-deformable precipitates. Strain hardening behaviour at high strains correlated with the reduction in spacing between grain boundary precipitates
