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R Elliott - One of the best experts on this subject based on the ideXlab platform.
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influence of molybdenum on austempering behaviour of ductile iron part 1 austempering kinetics and mechanical properties of ductile iron containing 0 13 mo
Materials Science and Technology, 1999Co-Authors: S. Yazdani, R ElliottAbstract:AbstractMeasurements of the austempering kinetics and mechanical properties are presented for a ductile iron of composition Fe–3·51C– 2·81Si–0·25Mn–0·39Cu–0·13Mo–0·04Mg (wt-%) for austempering temperatures of 285, 320, 375, and 400°C after austenitising at 870°C for 120 min. The kinetic studies show that the alloying level is insufficient to cause a significant delay in ausferrite formation in the intercellular boundaries. This implies that the heat treatment Processing Window is open for all austempering conditions studied. The mechanical property measurements show that with the correct selection of austempering temperature all the grades of the ASTM Standard 897M : 1990 and BS EN 1564 : 1997 can be satisfied. The hardenability of the present iron is limited and it is therefore unlikely that these standards will be achieved in thicker section components.
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influence of molybdenum on austempering behaviour of ductile iron part 2 influence of austenitising temperature on austempering kinetics mechanical properties and hardenability of ductile iron containing 0 13 mo
Materials Science and Technology, 1999Co-Authors: S. Yazdani, R ElliottAbstract:AbstractAustempering kinetic and mechanical property measurements are reported for austenitising temperatures of 950, 920, 870, and 840°C and an austempering temperature of 400°C for an iron of composition Fe–3·51C–2·81Si–0·25Mn–0·39Cu–0·13Mo– 0·04Mg. Increasing the austenitising temperature to improve the hardenability also narrows the heat treatment Processing Window but does not close it. Mechanical property measurements show that the ASTM Standard A897 : 1990 for ADI is satisfied using austenitising temperatures of 920, 870, and 840°C but the tensile properties just fail to satisfy the standard for an austenitising temperature of 950°C. This is attributed to the fact that the definition of the Processing Window does not allow for mechanical instability of the ausferrite structure. The properties satisfy the new European ADI standard BS EN 1564 : 1997 for all four austenitising temperatures.
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the relationship between austempering parameters microstructure and mechanical properties in a mn mo cu alloyed ductile iron
International Journal of Cast Metals Research, 1997Co-Authors: A Nazarboland, R ElliottAbstract:Measurements of ultimate tensile strength, 0.2% proof strength, elongation and unnotched Charpy impact energy are presented as a function of austempering time in the range from 1 to 4320 minutes for austempering temperatures of 400, 375 and 285 °C and austenitising temperatures of 870, 920 and 950 °C for a ductile iron of composition 3.39%C, 2.56% Si, 0.25% Mo, 0.29% Cu, 0.37% Mn and 0.04% Mg. Austempering kinetic measurements are presented for the various austenitising and austempering temperatures. These measurements are analysed to relate microstructure and mechanical properties and to define Processing Windows for the different austempering conditions. The analysis suggests a new definition for the closure time of the Processing Window. The newly defined Processing Windows are consistent with mechanical property observations in the present iron and a previously studied iron with the same base composition but containing 0.67% Mn.
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influence of austenitising temperature on austempering kinetics of high manganese alloyed ductile cast iron
Materials Science and Technology, 1995Co-Authors: H. Bayati, R Elliott, G.w. LorimerAbstract:AbstractX-ray diffraction, optical microscopy, and hardness measurements were used to determine the austenitising kinetics of an alloyed ductile iron containing 0·67%Mn, 0·25%Mo, and 0·25%Cu, during austempering at 285 and 375°C after austenitising at 870, 900, and 920°C. The austenitising kinetics show that 120 min is sufficient time to produce afully austenitic matrix. The stage I reaction during austempering occurs in two distinct steps: first in the eutectic cell and then in the intercellular areas. Decreasing the austenitising temperature is shown to increase the driving force for the stage I reaction but to have only a small effect on the stage II kinetics. Decreasing the austenitising temperature results in a more uniform austempered microstructure and reduces the amount of martensite in the structure. These changes shift the heat treatment Processing Window for high Mn irons to shorter timesfor austempering at 285°C and come close to, but do not open the Processing Window at 375°C.MST/3117
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austempering of low manganese ductile irons part 3 variation of mechanical properties with heat treatment conditions
Materials Science and Technology, 1993Co-Authors: N Darwish, R ElliottAbstract:AbstractMeasurements of 0·2% proof stress, ultimate tensile strength, elongation, and impact energy are presented for low Mn, Cu iron and low Mn, Ni–Cu iron as a function of austempering time, austempering temperature, and austenitising temperature. The mechanical properties show optimum values at times corresponding to the Processing Window derived from kinetic measurements. Austempering temperature is shown to influence the properties significantly and by varying the austempering temperature most of the grades of the standard ASTM A897M: 1990 can be achieved with the irons studied. Austenitising temperature is shown to influence the elongation and impact energy significantly at higher austempering temperatures and it is possible by lowering the austenitising temperature to open the Processing Window at a particular austempering temperature and improve the mechanical properties.MST/1899
R A Elliott - One of the best experts on this subject based on the ideXlab platform.
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influence of austenitising temperature on austempering of an mn mo cu alloyed ductile iron part 1 austempering kinetics and the Processing Window
Materials Science and Technology, 1996Co-Authors: R A ElliottAbstract:X-ray diffraction, optical microscopy, and hardness measurements were used to determine the austempering kinetics of an alloyed ductile iron of composition (wt-%) Fe-3·49C-2·33Si-0·42Mn-0·25Cu-0·23Mo-0·035Mg at austempering temperatures of 300, 350, 375, and 400°C and austenitising temperatures of 870 and 920°C. The stage I reaction during austempering occurs in two steps, the first in the eutectic cell and the second in the intercellular area. Decreasing the austenitising temperature is shown to increase the driving force for the stage I reaction but to have a lesser effect on the stage II reaction. Decreasing the austenitising temperature produces a more uniform austempered microstructure and reduces the amount of martensite in this structure. These changes move the Processing Window to shorter austempering times and increase the temperature at which the Processing Window closes.MST/3390
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austempering of an mn mo cu alloyed ductile iron part 1 austempering kinetics and Processing Window
Materials Science and Technology, 1996Co-Authors: R A ElliottAbstract:AbstractMicrostructural observations and measurements of the retained austenite content, hardness, austenite carbon content and unreacted austenite content are reported as a function of austempering time at 400, 375, 350, and 300°C after austenitising at 920°C for a ductile iron of composition (wt-%) Fe–3·49C–2·33Si–0·42Mn–0·004P–0·016S–0·25Cu–0·23Mo–0·035Mg. Solute profiles are presented which show solute segregation during solidification and that austenitising for 8 h does not remove the segregation. The segregation of Mo and Mn to intercellular areas is shown to result in stage I austempering reactions in the eutectic cell and intercellular region occurring at different austempering times. Evidence is provided of the occurrence of the stage II austempering reaction before the completion of the stage I reaction. The consequence of this sequence of changes is that the Processing Window is predicted to be closed for austempering temperatures of 400 and 375°C and open for temperatures of 350 and 300°C.MST/3392
Carolin Körner - One of the best experts on this subject based on the ideXlab platform.
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immediate development of Processing Windows for selective electron beam melting using layerwise monitoring via backscattered electron detection
Materials Letters, 2019Co-Authors: Christoph R Pobel, Christopher Arnold, Fuad Osmanlic, Carolin KörnerAbstract:Abstract The availability of a reliable Processing Window is the basic requirement for Processing new materials via selective electron beam melting (SEBM). Typically, these Processing Windows are derived by a time-consuming procedure comprising fabrication, metallographic preparation and analysis of standardized specimens for every parameter set. This study demonstrates the immediate development of a Processing Window during one single SEBM process. An electron optical image acquisition system provides the necessary information for evaluation and subsequent adaption of process parameters. It is shown that this immediate approach delivers Processing Windows with sufficient accuracy, while the required time is substantially reduced from weeks or even months to several hours.
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Processing Window and evaporation phenomena for ti 6al 4v produced by selective electron beam melting
Acta Materialia, 2014Co-Authors: Vera Juechter, Thorsten Scharowsky, Robert F Singer, Carolin KörnerAbstract:Abstract Additive manufacturing by selective electron beam melting is a promising way to fabricate complex Ti–6Al–4V components. Sound parts can be realized by applying quite different Processing strategies, which have an influence not only on Processing time but also on the microstructure and the alloy composition. In this work, the Processing Window for Ti–6Al–4V is determined for a wide range of scanning speeds and line energies. The influence of the energy input on the resulting heat-affected zone and alloy composition is discussed.
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Additive manufacturing of nickel-based superalloy Inconel 718 by selective electron beam melting: Processing Window and microstructure
Journal of Materials Research, 2014Co-Authors: Harald Ernst Helmer, Carolin Körner, Robert Friedrich SingerAbstract:Cube-shaped IN718 samples were produced by selective electron beam melting (SEBM) with varying beam power, deflection speed, and beam spot size. Process parameter Windows were identified where fully dense samples are obtained with no surface unevenness. High deflection speeds were demonstrated to result in smaller demand of area energy. This result is explained by the reduced time for heat dissipation into the substrate during hatching. The grain structure was strongly affected by SEBM process parameters. Under certain conditions, epitaxial growth over many layers and well-developed columnar grain structures were obtained with a polycrystalline substrate plate. A more defocused beam led to a lower melt pool temperature and shallower melt pool geometry where maximum temperature gradients and solidification rates were more or less in parallel with the building direction and primary dendrite arm orientation. These conditions help to suppress grain nucleation ahead of the nucleation front as vigorous melt movement, fragmentation of dendrites, and tertiary arm growth are suppressed.
N Darwish - One of the best experts on this subject based on the ideXlab platform.
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austempering of low manganese ductile irons part 3 variation of mechanical properties with heat treatment conditions
Materials Science and Technology, 1993Co-Authors: N Darwish, R ElliottAbstract:AbstractMeasurements of 0·2% proof stress, ultimate tensile strength, elongation, and impact energy are presented for low Mn, Cu iron and low Mn, Ni–Cu iron as a function of austempering time, austempering temperature, and austenitising temperature. The mechanical properties show optimum values at times corresponding to the Processing Window derived from kinetic measurements. Austempering temperature is shown to influence the properties significantly and by varying the austempering temperature most of the grades of the standard ASTM A897M: 1990 can be achieved with the irons studied. Austenitising temperature is shown to influence the elongation and impact energy significantly at higher austempering temperatures and it is possible by lowering the austenitising temperature to open the Processing Window at a particular austempering temperature and improve the mechanical properties.MST/1899
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austempering of low manganese ductile irons
Materials Science and Technology, 1993Co-Authors: N Darwish, R ElliottAbstract:AbstractX-ray diffraction, optical microscopy, and hardness measurements were used to determine the austenitising kinetics and the stage I and stage II austempering kinetics of a low Mn, Cu iron and a low Mn, Ni–Cu iron during austempering at 300, 370, and 440°C after austenitising at 900, 950, and 1000°C. The study of the austenitising kinetics shows that 60 min is sufficient time to produce a constant C austenite content and that the kinetics are influenced strongly by the volume fraction of pearlite in the structure to be austenitised. Decreasing the austenitising temperature is shown to increase the driving force for the stage I reaction but to have only a small effect on the stage II kinetics. This shifts the heat treatment Processing Window to shorter times and can open a Processing Window that is closed for higher austenitising temperatures. Decreasing the austenitising temperature results in a more uniform austempered microstructure and reduces the amount of martensite in this structure. Decreasin...
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austempering of low manganese ductile irons i Processing Window
Materials Science and Technology, 1993Co-Authors: N Darwish, R ElliottAbstract:X-ray diffraction and optical microscopy were used folollow the stage I and stage II kinetics of a low Mn, Cu iron and a low Mn, Ni-Cu iron during austempering at 300, 370, and 440 o C. Nickel and Cu are shown to delay the bainitic transformation without the undesirable features displayed by Mn and Mo and to influence the stage I kinetics through their effect on the C content of the austenite. The rate of transformation varies with the driving force for the transformation. In contrast, the rate at which the stage II reaction proceeds depends on the total alloying content through its effect on the nucleation and/or growth of the ferrite and carbide phases
Zhen Wang - One of the best experts on this subject based on the ideXlab platform.
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low band gap conjugated polymers combining siloxane terminated side chains and alkyl side chains side chain engineering achieving a large active layer Processing Window for pce 10 in polymer solar cells
Journal of Materials Chemistry, 2017Co-Authors: Li Nian, Lianjie Zhang, Lechi Qing, Zhen Wang, Lei Ying, Junwu ChenAbstract:Alternating and random conjugated copolymers with a siloxane-terminated side chain for a repeating unit based on 5,6-difluoro[2,1,3]benzothiadiazole (FBT) and quarterthiophene (4T) were synthesized, among which side-chain random copolymers PFBT4T-C5Si-50% and PFBT4T-C5Si-25% with low contents of 50% and 25% siloxane-terminated side chains, respectively, in conjunction with alkyl side chains were found to be more suitable for optoelectronic applications due to good film-forming in solution Processing. Grazing incidence X-ray diffraction (GIXD) indicated that the siloxane-terminated side chain could induce PFBT4T-C5Si-50% and PFBT4T-C5Si-25% with face-on orientations, giving high 3-D hole transport in neat films as supported by a high hole mobility up to 2.46 cm2 V−1 s−1 in field-effect transistors and an SCLC hole mobility up to 5.9 × 10−2 cm2 V−1 s−1 in hole-only devices. Fast SCLC hole and electron transports were seen for their bulk-heterojunction (BHJ) blend films with PC71BM as the acceptor, due to the retention of a polymer face-on orientation. The BHJ blend film of PFBT4T-C5Si-25% showed lower film surface roughness, more balanced hole and electron transport, and relatively smaller phase separation when compared with PFBT4T-C5Si-50%, as evidenced by atomic force microscopy (AFM), transmission electron microscopy (TEM), SCLC, and resonant soft X-ray scattering (RSoXS) measurements. The PFBT4T-C5Si-25%-based PSCs with 270, 420, and 600 nm thick active layers exhibited outstanding power conversion efficiencies (PCEs) of 10.39%, 11.09%, and 10.15%, respectively, readily offering a high thickness tolerance to achieve an unprecedented wide active layer Processing Window for PCE > 10%. This is also the first PCE of more than 10% achieved by an active layer of a 600 nm thickness level in PSCs. Another notable feature is very high fill factors of more than 74% and 71% being achieved for very thick active layers of 420 and 600 nm, respectively. The results suggest that side-chain engineering through the incorporation of a partial siloxane-terminated side chain is a unique handle to afford new photovoltaic polymers with enhanced vertical carrier transport towards application in roll-to-roll Processing of PSCs.
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low band gap conjugated polymers combining siloxane terminated side chains and alkyl side chains side chain engineering achieving a large active layer Processing Window for pce 10 in polymer solar cells
Journal of Materials Chemistry, 2017Co-Authors: Xuncheng Liu, Li Nian, Lianjie Zhang, Lechi Qing, Zhen Wang, Lei Ying, Ke Gao, Zengqi Xie, Yong Cao, Feng LiuAbstract:Alternating and random conjugated copolymers with a siloxane-terminated side chain for a repeating unit based on 5,6-difluoro[2,1,3]benzothiadiazole (FBT) and quarterthiophene (4T) were synthesized, among which side-chain random copolymers PFBT4T-C5Si-50% and PFBT4T-C5Si-25% with low contents of 50% and 25% siloxane-terminated side chains, respectively, in conjunction with alkyl side chains were found to be more suitable for optoelectronic applications due to good film-forming in solution Processing. Grazing incidence X-ray diffraction (GIXD) indicated that the siloxane-terminated side chain could induce PFBT4T-C5Si-50% and PFBT4T-C5Si-25% with face-on orientations, giving high 3-D hole transport in neat films as supported by a high hole mobility up to 2.46 cm2 V−1 s−1 in field-effect transistors and an SCLC hole mobility up to 5.9 × 10−2 cm2 V−1 s−1 in hole-only devices. Fast SCLC hole and electron transports were seen for their bulk-heterojunction (BHJ) blend films with PC71BM as the acceptor, due to the retention of a polymer face-on orientation. The BHJ blend film of PFBT4T-C5Si-25% showed lower film surface roughness, more balanced hole and electron transport, and relatively smaller phase separation when compared with PFBT4T-C5Si-50%, as evidenced by atomic force microscopy (AFM), transmission electron microscopy (TEM), SCLC, and resonant soft X-ray scattering (RSoXS) measurements. The PFBT4T-C5Si-25%-based PSCs with 270, 420, and 600 nm thick active layers exhibited outstanding power conversion efficiencies (PCEs) of 10.39%, 11.09%, and 10.15%, respectively, readily offering a high thickness tolerance to achieve an unprecedented wide active layer Processing Window for PCE > 10%. This is also the first PCE of more than 10% achieved by an active layer of a 600 nm thickness level in PSCs. Another notable feature is very high fill factors of more than 74% and 71% being achieved for very thick active layers of 420 and 600 nm, respectively. The results suggest that side-chain engineering through the incorporation of a partial siloxane-terminated side chain is a unique handle to afford new photovoltaic polymers with enhanced vertical carrier transport towards application in roll-to-roll Processing of PSCs.
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a Processing Window for fabricating heavily doped silicon nanowires by metal assisted chemical etching
Journal of Physical Chemistry C, 2013Co-Authors: Zhen Wang, Mingliang Zhang, Fuhua Yang, Xiaodong WangAbstract:Heavily doped silicon nanowires (SiNWs) with controllable doping concentrations can be used in many fields because of their unique characteristics. However, it is difficult to fabricate long heavil...
