The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
C M Sellars - One of the best experts on this subject based on the ideXlab platform.
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a comparison between containerless melting twin piston Splat Quenching and chill block melt spinning as techniques for rapid solidification of late transition metal aluminides
Materials Letters, 1992Co-Authors: U Prakash, H. Jones, R A Buckley, C M SellarsAbstract:Abstract Some results of comparative studies of the conditions for producing rapidly solidified samples of late transition metal aluminides by Splat Quenching and melt spinning are reported. These suggest that, while wettability of the substrate by the melt is a necessary condition for success in chill-block melt spinning, the reverse can be the case for Splat Quenching. The minimum mass for sample levitation for melting and twin-piston Splatting was found to be strongly dependent on alloy composition in this group of aluminides.
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A comparison between containerless melting/twin-piston Splat Quenching and chill-block melt spinning as techniques for rapid solidification of late transition metal aluminides
Materials Letters, 1992Co-Authors: U Prakash, H. Jones, R A Buckley, C M SellarsAbstract:Abstract Some results of comparative studies of the conditions for producing rapidly solidified samples of late transition metal aluminides by Splat Quenching and melt spinning are reported. These suggest that, while wettability of the substrate by the melt is a necessary condition for success in chill-block melt spinning, the reverse can be the case for Splat Quenching. The minimum mass for sample levitation for melting and twin-piston Splatting was found to be strongly dependent on alloy composition in this group of aluminides.
H. Jones - One of the best experts on this subject based on the ideXlab platform.
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Chapter 3 Rapid solidification
Non-equilibrium Processing of Materials, 1999Co-Authors: H. JonesAbstract:Publisher Summary This chapter discusses the different aspects of rapid solidification. Rapid solidification produces changes in constitution, because the large undercoolings and front velocities involved promote formation of nonequilibrium phases and extensions in composition range of surviving equilibrium phases. Microstructural differences include changes in the mode of growth and size refinement, as a result of the short diffusion distances imposed. Formation of nonequilibrium crystalline phases, by rapid solidification, occurs when their nucleation and growth kinetics results in a higher rate of formation than the competing equilibrium phase. Formation of metastable cast irons rather than graphitic cast irons at temperatures below the austenite–cementite eutectic temperature is a well-known example for relatively modest cooling rates. Possibilities for such metastable phase formation multiply manyfold at the high undercoolings and cooling rates that typify processes such as melt-spinning and Splat Quenching. Crystalline materials made by rapid solidification can also show high hardness and strength by combinations of fine grain size, presence of fine disperoids/precipitation, and increased solid solution hardening, without the reduced stiffness, associated with the glassy state.
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Cooling rates during rapid solidification from a chill surface
Materials Letters, 1996Co-Authors: H. JonesAbstract:Abstract Available measurements of cooling rate T associated with solidification in Splat Quenching, chill casting are melt spinning are reassessed in relation to the predicted limits set by Newtonian and ideal cooling. Measurements are shown to lie typically within the limits 0.01 T = φA ∞ Z 2 with most for Splat Quenching an corresponding to near-ideal cooling and most for melt spinning conforming to near-Newtonian conditions.
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Effect of rapid solidification, impurity level, and further alloy additions on dissolution rate of Mg–Mn alloys in 3%NaCl solution
Materials Science and Technology, 1993Co-Authors: D. Rugg, R. G. J. Edyvean, H. JonesAbstract:AbstractGravimetric and hydrogen evolution methods have been used to determine the effect of binary Mn and ternary Nd, Y, Ni, Cu, and Si alloy additions on the dissolution rate x of Splat quenched Mg in 3%NaCl solution, using the ingot or chill cast condition as a reference condition. The results indicate that Splat Quenching leads to a reduction in x for Mg, Mg–Mn, and Mg–Mn–Nd, the presence of Mn resulting in a decrease in x with time of immersion to values
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a comparison between containerless melting twin piston Splat Quenching and chill block melt spinning as techniques for rapid solidification of late transition metal aluminides
Materials Letters, 1992Co-Authors: U Prakash, H. Jones, R A Buckley, C M SellarsAbstract:Abstract Some results of comparative studies of the conditions for producing rapidly solidified samples of late transition metal aluminides by Splat Quenching and melt spinning are reported. These suggest that, while wettability of the substrate by the melt is a necessary condition for success in chill-block melt spinning, the reverse can be the case for Splat Quenching. The minimum mass for sample levitation for melting and twin-piston Splatting was found to be strongly dependent on alloy composition in this group of aluminides.
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A comparison between containerless melting/twin-piston Splat Quenching and chill-block melt spinning as techniques for rapid solidification of late transition metal aluminides
Materials Letters, 1992Co-Authors: U Prakash, H. Jones, R A Buckley, C M SellarsAbstract:Abstract Some results of comparative studies of the conditions for producing rapidly solidified samples of late transition metal aluminides by Splat Quenching and melt spinning are reported. These suggest that, while wettability of the substrate by the melt is a necessary condition for success in chill-block melt spinning, the reverse can be the case for Splat Quenching. The minimum mass for sample levitation for melting and twin-piston Splatting was found to be strongly dependent on alloy composition in this group of aluminides.
Kazuhiko Kuribayashi - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of metastable rare earth iron garnet formed at the melt substrate interface by Splat Quenching
Journal of the American Ceramic Society, 2007Co-Authors: Kosuke Nagashio, Kazuhiko Kuribayashi, O Yamaguchi, Taketoshi HibiyaAbstract:The Nd substitution limit in the NdxSm3−xFe5O12 garnet can be metastably extended from x=0.375 up to x=2.0 by Splat Quenching combined with containerless processing. To understand the rapid solidification process at the melt/substrate interface, a droplet with NdxSm3−xFe5O12 composition (x=0.43) was dropped by free fall on a Si wafer having relatively high thermal conductivity. The sequence of dropping, impacting, spreading, and solidification of the droplet was monitored using an infrared high-speed video camera through the Si wafer from the bottom. When the droplet impinged on the Si wafer, an amorphous layer was formed at the initial impact. Then, the metastable garnet nucleated on it, resulting in the first recalescence. Subsequently, the second recalescence of the perovskite, which is stable above the peritectic temperature and identified as a high-temperature phase, was observed ∼3 ms later. This time lag may be ascribed to the considerably low growth rate of the metastable garnet and the difficulty of nucleation of the perovskite on the metastable garnet. This is the first time that the phase transition at the melt/substrate interface during rapid Quenching was observed in situ.
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In Situ Observation of Metastable Rare‐Earth Iron Garnet Formed at the Melt/Substrate Interface by Splat Quenching
Journal of the American Ceramic Society, 2007Co-Authors: Kosuke Nagashio, Kazuhiko Kuribayashi, O Yamaguchi, Taketoshi HibiyaAbstract:The Nd substitution limit in the NdxSm3−xFe5O12 garnet can be metastably extended from x=0.375 up to x=2.0 by Splat Quenching combined with containerless processing. To understand the rapid solidification process at the melt/substrate interface, a droplet with NdxSm3−xFe5O12 composition (x=0.43) was dropped by free fall on a Si wafer having relatively high thermal conductivity. The sequence of dropping, impacting, spreading, and solidification of the droplet was monitored using an infrared high-speed video camera through the Si wafer from the bottom. When the droplet impinged on the Si wafer, an amorphous layer was formed at the initial impact. Then, the metastable garnet nucleated on it, resulting in the first recalescence. Subsequently, the second recalescence of the perovskite, which is stable above the peritectic temperature and identified as a high-temperature phase, was observed ∼3 ms later. This time lag may be ascribed to the considerably low growth rate of the metastable garnet and the difficulty of nucleation of the perovskite on the metastable garnet. This is the first time that the phase transition at the melt/substrate interface during rapid Quenching was observed in situ.
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formation of metastable rare earth iron garnet by Splat Quenching
Journal of the American Ceramic Society, 2006Co-Authors: Kosuke Nagashio, O Yamaguchi, Taketoshi Hibiya, Kazuhiko KuribayashiAbstract:The droplet with NdxSm3−xFe5O12 composition was undercooled in an aerodynamic levitator and Splat quenched by copper anvils in order to obtain a metastable garnet with a solubility limit larger than the phase equilibrium solubility limit, x=0.375, for the NdxSm3−xFe5O12 system. The peaks of the garnet were identified with the peaks of the perovskite by powder X-ray diffraction (XRD), although the peak intensity for the garnet decreased with increasing the Nd substitution from x=0.43 to 0.2, and finally disappeared at x=2.2. When the garnet was annealed at 1570 K for 24 h in air, it transformed into a mixture of perovskite and hematite, which indicates that the garnet obtained was the metastable phase. Moreover, the amorphous phase was found in the central part of all the samples even at x=2.2, which was confirmed by micro-focus XRD. The formation of the constituent phases in the as-quenched sample was discussed using a continuous cooling transformation diagram.
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Formation of Metastable Rare‐Earth Iron Garnet by Splat Quenching
Journal of the American Ceramic Society, 2006Co-Authors: Kosuke Nagashio, O Yamaguchi, Taketoshi Hibiya, Kazuhiko KuribayashiAbstract:The droplet with NdxSm3−xFe5O12 composition was undercooled in an aerodynamic levitator and Splat quenched by copper anvils in order to obtain a metastable garnet with a solubility limit larger than the phase equilibrium solubility limit, x=0.375, for the NdxSm3−xFe5O12 system. The peaks of the garnet were identified with the peaks of the perovskite by powder X-ray diffraction (XRD), although the peak intensity for the garnet decreased with increasing the Nd substitution from x=0.43 to 0.2, and finally disappeared at x=2.2. When the garnet was annealed at 1570 K for 24 h in air, it transformed into a mixture of perovskite and hematite, which indicates that the garnet obtained was the metastable phase. Moreover, the amorphous phase was found in the central part of all the samples even at x=2.2, which was confirmed by micro-focus XRD. The formation of the constituent phases in the as-quenched sample was discussed using a continuous cooling transformation diagram.
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containerless solidification and net shaping by Splat Quenching of undercooled nd2fe14b melts
Materials Transactions, 2003Co-Authors: Kosuke Nagashio, Mingjun Li, Kazuhiko KuribayashiAbstract:High-speed optical temperature measurement and digital imaging elucidated the solidification behavior of undercooled Nd2Fe14B melt through containerless processing by an electromagnetic levitation method. The Fe phase solidified primarily from the melt. Subsequently, the remaining melt was undercooled below the peritectic temperature and the Nd2Fe14B phase surrounded the primary Fe dendrites, yielding the recalescence. The clear interface of the thermal field propagated and covered the entire sample. Detailed microstructural observation showed that the Nd2Fe14B phase surrounding the different Fe dendrites mutually came into contact with the several points. This suggested that many sites for nucleation of the Nd2Fe14B phase are not necessary for the successive growth of the Nd2Fe14B phase that was maintained by the spread of the Nd2Fe14B phase to the different primary Fe dendrites. This resulted in the macroscopic interface of the thermal field during recalescence. Moreover, the undercooled melt was dropped from the levitation coil and quenched by a pair of copper chill plates with moulds, the shape of which is a hemisphere cap, in order to obtain a small bulk sample for industrial purpose. The spherical sample with the diameter of 5 mm was successively obtained without decreasing the cooling rate. This result suggests the possibility of the net shaping of a small magnet from the melt.
Taketoshi Hibiya - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of metastable rare earth iron garnet formed at the melt substrate interface by Splat Quenching
Journal of the American Ceramic Society, 2007Co-Authors: Kosuke Nagashio, Kazuhiko Kuribayashi, O Yamaguchi, Taketoshi HibiyaAbstract:The Nd substitution limit in the NdxSm3−xFe5O12 garnet can be metastably extended from x=0.375 up to x=2.0 by Splat Quenching combined with containerless processing. To understand the rapid solidification process at the melt/substrate interface, a droplet with NdxSm3−xFe5O12 composition (x=0.43) was dropped by free fall on a Si wafer having relatively high thermal conductivity. The sequence of dropping, impacting, spreading, and solidification of the droplet was monitored using an infrared high-speed video camera through the Si wafer from the bottom. When the droplet impinged on the Si wafer, an amorphous layer was formed at the initial impact. Then, the metastable garnet nucleated on it, resulting in the first recalescence. Subsequently, the second recalescence of the perovskite, which is stable above the peritectic temperature and identified as a high-temperature phase, was observed ∼3 ms later. This time lag may be ascribed to the considerably low growth rate of the metastable garnet and the difficulty of nucleation of the perovskite on the metastable garnet. This is the first time that the phase transition at the melt/substrate interface during rapid Quenching was observed in situ.
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In Situ Observation of Metastable Rare‐Earth Iron Garnet Formed at the Melt/Substrate Interface by Splat Quenching
Journal of the American Ceramic Society, 2007Co-Authors: Kosuke Nagashio, Kazuhiko Kuribayashi, O Yamaguchi, Taketoshi HibiyaAbstract:The Nd substitution limit in the NdxSm3−xFe5O12 garnet can be metastably extended from x=0.375 up to x=2.0 by Splat Quenching combined with containerless processing. To understand the rapid solidification process at the melt/substrate interface, a droplet with NdxSm3−xFe5O12 composition (x=0.43) was dropped by free fall on a Si wafer having relatively high thermal conductivity. The sequence of dropping, impacting, spreading, and solidification of the droplet was monitored using an infrared high-speed video camera through the Si wafer from the bottom. When the droplet impinged on the Si wafer, an amorphous layer was formed at the initial impact. Then, the metastable garnet nucleated on it, resulting in the first recalescence. Subsequently, the second recalescence of the perovskite, which is stable above the peritectic temperature and identified as a high-temperature phase, was observed ∼3 ms later. This time lag may be ascribed to the considerably low growth rate of the metastable garnet and the difficulty of nucleation of the perovskite on the metastable garnet. This is the first time that the phase transition at the melt/substrate interface during rapid Quenching was observed in situ.
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formation of metastable rare earth iron garnet by Splat Quenching
Journal of the American Ceramic Society, 2006Co-Authors: Kosuke Nagashio, O Yamaguchi, Taketoshi Hibiya, Kazuhiko KuribayashiAbstract:The droplet with NdxSm3−xFe5O12 composition was undercooled in an aerodynamic levitator and Splat quenched by copper anvils in order to obtain a metastable garnet with a solubility limit larger than the phase equilibrium solubility limit, x=0.375, for the NdxSm3−xFe5O12 system. The peaks of the garnet were identified with the peaks of the perovskite by powder X-ray diffraction (XRD), although the peak intensity for the garnet decreased with increasing the Nd substitution from x=0.43 to 0.2, and finally disappeared at x=2.2. When the garnet was annealed at 1570 K for 24 h in air, it transformed into a mixture of perovskite and hematite, which indicates that the garnet obtained was the metastable phase. Moreover, the amorphous phase was found in the central part of all the samples even at x=2.2, which was confirmed by micro-focus XRD. The formation of the constituent phases in the as-quenched sample was discussed using a continuous cooling transformation diagram.
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Formation of Metastable Rare‐Earth Iron Garnet by Splat Quenching
Journal of the American Ceramic Society, 2006Co-Authors: Kosuke Nagashio, O Yamaguchi, Taketoshi Hibiya, Kazuhiko KuribayashiAbstract:The droplet with NdxSm3−xFe5O12 composition was undercooled in an aerodynamic levitator and Splat quenched by copper anvils in order to obtain a metastable garnet with a solubility limit larger than the phase equilibrium solubility limit, x=0.375, for the NdxSm3−xFe5O12 system. The peaks of the garnet were identified with the peaks of the perovskite by powder X-ray diffraction (XRD), although the peak intensity for the garnet decreased with increasing the Nd substitution from x=0.43 to 0.2, and finally disappeared at x=2.2. When the garnet was annealed at 1570 K for 24 h in air, it transformed into a mixture of perovskite and hematite, which indicates that the garnet obtained was the metastable phase. Moreover, the amorphous phase was found in the central part of all the samples even at x=2.2, which was confirmed by micro-focus XRD. The formation of the constituent phases in the as-quenched sample was discussed using a continuous cooling transformation diagram.
Kosuke Nagashio - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of metastable rare earth iron garnet formed at the melt substrate interface by Splat Quenching
Journal of the American Ceramic Society, 2007Co-Authors: Kosuke Nagashio, Kazuhiko Kuribayashi, O Yamaguchi, Taketoshi HibiyaAbstract:The Nd substitution limit in the NdxSm3−xFe5O12 garnet can be metastably extended from x=0.375 up to x=2.0 by Splat Quenching combined with containerless processing. To understand the rapid solidification process at the melt/substrate interface, a droplet with NdxSm3−xFe5O12 composition (x=0.43) was dropped by free fall on a Si wafer having relatively high thermal conductivity. The sequence of dropping, impacting, spreading, and solidification of the droplet was monitored using an infrared high-speed video camera through the Si wafer from the bottom. When the droplet impinged on the Si wafer, an amorphous layer was formed at the initial impact. Then, the metastable garnet nucleated on it, resulting in the first recalescence. Subsequently, the second recalescence of the perovskite, which is stable above the peritectic temperature and identified as a high-temperature phase, was observed ∼3 ms later. This time lag may be ascribed to the considerably low growth rate of the metastable garnet and the difficulty of nucleation of the perovskite on the metastable garnet. This is the first time that the phase transition at the melt/substrate interface during rapid Quenching was observed in situ.
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In Situ Observation of Metastable Rare‐Earth Iron Garnet Formed at the Melt/Substrate Interface by Splat Quenching
Journal of the American Ceramic Society, 2007Co-Authors: Kosuke Nagashio, Kazuhiko Kuribayashi, O Yamaguchi, Taketoshi HibiyaAbstract:The Nd substitution limit in the NdxSm3−xFe5O12 garnet can be metastably extended from x=0.375 up to x=2.0 by Splat Quenching combined with containerless processing. To understand the rapid solidification process at the melt/substrate interface, a droplet with NdxSm3−xFe5O12 composition (x=0.43) was dropped by free fall on a Si wafer having relatively high thermal conductivity. The sequence of dropping, impacting, spreading, and solidification of the droplet was monitored using an infrared high-speed video camera through the Si wafer from the bottom. When the droplet impinged on the Si wafer, an amorphous layer was formed at the initial impact. Then, the metastable garnet nucleated on it, resulting in the first recalescence. Subsequently, the second recalescence of the perovskite, which is stable above the peritectic temperature and identified as a high-temperature phase, was observed ∼3 ms later. This time lag may be ascribed to the considerably low growth rate of the metastable garnet and the difficulty of nucleation of the perovskite on the metastable garnet. This is the first time that the phase transition at the melt/substrate interface during rapid Quenching was observed in situ.
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formation of metastable rare earth iron garnet by Splat Quenching
Journal of the American Ceramic Society, 2006Co-Authors: Kosuke Nagashio, O Yamaguchi, Taketoshi Hibiya, Kazuhiko KuribayashiAbstract:The droplet with NdxSm3−xFe5O12 composition was undercooled in an aerodynamic levitator and Splat quenched by copper anvils in order to obtain a metastable garnet with a solubility limit larger than the phase equilibrium solubility limit, x=0.375, for the NdxSm3−xFe5O12 system. The peaks of the garnet were identified with the peaks of the perovskite by powder X-ray diffraction (XRD), although the peak intensity for the garnet decreased with increasing the Nd substitution from x=0.43 to 0.2, and finally disappeared at x=2.2. When the garnet was annealed at 1570 K for 24 h in air, it transformed into a mixture of perovskite and hematite, which indicates that the garnet obtained was the metastable phase. Moreover, the amorphous phase was found in the central part of all the samples even at x=2.2, which was confirmed by micro-focus XRD. The formation of the constituent phases in the as-quenched sample was discussed using a continuous cooling transformation diagram.
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Formation of Metastable Rare‐Earth Iron Garnet by Splat Quenching
Journal of the American Ceramic Society, 2006Co-Authors: Kosuke Nagashio, O Yamaguchi, Taketoshi Hibiya, Kazuhiko KuribayashiAbstract:The droplet with NdxSm3−xFe5O12 composition was undercooled in an aerodynamic levitator and Splat quenched by copper anvils in order to obtain a metastable garnet with a solubility limit larger than the phase equilibrium solubility limit, x=0.375, for the NdxSm3−xFe5O12 system. The peaks of the garnet were identified with the peaks of the perovskite by powder X-ray diffraction (XRD), although the peak intensity for the garnet decreased with increasing the Nd substitution from x=0.43 to 0.2, and finally disappeared at x=2.2. When the garnet was annealed at 1570 K for 24 h in air, it transformed into a mixture of perovskite and hematite, which indicates that the garnet obtained was the metastable phase. Moreover, the amorphous phase was found in the central part of all the samples even at x=2.2, which was confirmed by micro-focus XRD. The formation of the constituent phases in the as-quenched sample was discussed using a continuous cooling transformation diagram.
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containerless solidification and net shaping by Splat Quenching of undercooled nd2fe14b melts
Materials Transactions, 2003Co-Authors: Kosuke Nagashio, Mingjun Li, Kazuhiko KuribayashiAbstract:High-speed optical temperature measurement and digital imaging elucidated the solidification behavior of undercooled Nd2Fe14B melt through containerless processing by an electromagnetic levitation method. The Fe phase solidified primarily from the melt. Subsequently, the remaining melt was undercooled below the peritectic temperature and the Nd2Fe14B phase surrounded the primary Fe dendrites, yielding the recalescence. The clear interface of the thermal field propagated and covered the entire sample. Detailed microstructural observation showed that the Nd2Fe14B phase surrounding the different Fe dendrites mutually came into contact with the several points. This suggested that many sites for nucleation of the Nd2Fe14B phase are not necessary for the successive growth of the Nd2Fe14B phase that was maintained by the spread of the Nd2Fe14B phase to the different primary Fe dendrites. This resulted in the macroscopic interface of the thermal field during recalescence. Moreover, the undercooled melt was dropped from the levitation coil and quenched by a pair of copper chill plates with moulds, the shape of which is a hemisphere cap, in order to obtain a small bulk sample for industrial purpose. The spherical sample with the diameter of 5 mm was successively obtained without decreasing the cooling rate. This result suggests the possibility of the net shaping of a small magnet from the melt.
