Dual purpose pyrometer for temperature and solidification velocity measurement

Hofmeister, William; Bayuzick, R. J.; Robinson, Michael B.

doi:10.1063/1.1141393

Cited by 43 publications

(16 citation statements)

References 9 publications

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“…Other researchers have employed electromagnetic levitation to study the growth velocity. [26,27,28] Basler et al [29] were among the first to use a linear array of photo-diodes, later moving to a twodimensional array-in an effort to improve the spatial resolution of their studies. Recently, electronic imaging technology has allowed direct visual observation of growth front in undercooled ingot.…”

Section: Introductionmentioning

confidence: 99%

Solidification behavior and microstructural evolution during laser beam—material interaction

Mohanty

Mazumder

1998

Metall Mater Trans B

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A laser-assisted visualization technique has been used to monitor the solidification behavior at the tail of a molten pool created by scanning high energy density laser beam. A high speed digital camera with spatial resolution of 64 ϫ 64 pixels and temporal resolution of 40,500 frames/s has been employed along with a novel concept of illuminating the interaction zone by a secondary visible probe laser. This technique enabled in situ monitoring of the solid/liquid interface due to the characteristic difference in the reflectivity between solid and liquid surfaces. It is observed that the solidification behavior is unstable and is highly influenced by the instabilities in the flow, which develop from the complex laser-material interaction process. Quite often the growth front remelted back due to the fluctuating thermal field driven by flow instability. The fluctuations in the growth front and the fluctuations in the laser-material interaction process have been monitored simultaneously, however, no correlation is apparent. The influence of flow instability on the resulting microstructure has been analyzed.

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Section: Introductionmentioning

confidence: 99%

Solidification behavior and microstructural evolution during laser beam—material interaction

Mohanty

Mazumder

1998

Metall Mater Trans B

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“…This constraint is less stringent for high undercooling than for low, but still needs to be considered. It is reflected in the fact that, with larger W, the interface velocity V in the phase-field model becomes a nonlinear function of the interface undercooling for the high velocity range (30À60 m/s) measured experimentally in Ni [165][166][167][168][169]. In particular, the model exhibits a cross-over from a linear dependence, V $ DT I , to a square-root dependence, V $ DT 1=2 I for large DT I , with the cross-over occurring at smaller DT I for a larger W in the model.…”

Section: Linking Atomistic Simulation With Phase Field Modelingmentioning

confidence: 99%

“…We focus on deeply undercooled Ni melts for which experimental measurements of dendrite growth rates have been obtained by various groups [165][166][167][168][169] and hence, a direct quantitative comparison of model predictions and experimental measurements can be made in this system. It should be noted that pioneering work on the study of highly undercooled melts was performed by Glicksman and Schaefer [138] on white phosphorous.…”

Section: Linking Atomistic Simulation With Phase Field Modelingmentioning

confidence: 99%

Atomistic and continuum modeling of dendritic solidification

Hoyt

2003

Materials Science and Engineering: R: Reports

398

220

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“…The measured data and calculated results agree well with each other at small undercooling, however large deviation occurs at large undercooling, which was also observed in ref. [16]. The α-Ni dendrite growth velocity in Ni-10%Cu-10%Fe-10%Co alloy is an exponential function of undercooling, which can be expressed as…”

Section: Rapid Solidification Characteristicsmentioning

confidence: 99%

Rapid dendrite growth in quaternary Ni-based alloys

et al. 2006

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The high undercooling and rapid solidification of Ni-10%Cu-10%Fe-10%Co quaternary alloy were achieved by electromagnetic levitation and glass fluxing techniques. The maximum undercooling of 276 K (0.16TL) was obtained in the experiments. All the solidified samples are determined to be α-Ni single-phase solid solutions by DSC thermal analysis and X-ray diffraction analysis. The microstructure of the α-Ni solid solution phase transfers from dendrite to equiaxed grain with an increase in undercooling, accompanied by the grain refinement effect. When the undercooling is very large, the solute trapping effect becomes quite significant and the microsegregation is suppressed. The experimental measurement of α-Ni dendrite growth velocity indicates that it increases with undercooling according to the relation,Dendritic growth is one of the most common microstructural formation mechanisms during crystal growth. Its morphology provides the kinetics information of crystal growth. Therefore, it is valuable to perform the research on rapid dendrite growth in order to find the relation between the microstructure and experimental conditions, which has also important practical significance for the development of new materials. The dendrite growth has been intensively investigated theoretically [1][2][3] . Up to now, LKT/BCT model [4,5] is the most successful model to describe the rapid dendrite growth process, which can well describe the dendrite growth mechanism of pure metal and binary alloys [6,7] . But for multicomponent alloys, the LKT/BCT model is not applicable due to the coupling of the diffusion fields of different solutes [8,9] . And thus it is necessary to carry out quantitative experimental research on the rapid dendrite growth of multicomponent alloys and develop more suitable dendrite growth models.The undercooling techniques provide experimental possibility to investigate dendrite growth under the nonequilibrium conditions. The glass fluxing technique and electromagnetic levitation processing, which can avoid the contamination from crucible walls, are widely applied to achieve the high undercooling of metallic melts [10,11] . The objective of this work is to acquire the undercooling and rapid dendrite growth of Ni-10%Cu-10%Fe-10%Co quaternary alloy by the glass fluxing and electromagnetic levitation techniques. The dendrite growth velocities are measured experimentally as a function of undercooling. Meanwhile, the dendrite growth mechanism of this alloy is discussed. Experimental proceduresThe master alloy was prepared from 99.99% pure Ni, 99.99% pure Fe, 99.99% pure Co and 99.999% pure Cu in an arc melting furnace and each sample has a mass of 1.5 g. The fluxing agent was synthesized by 50%Na 2 SiO 3 +30%SiO 2 +11.82%Na 2 B 4 O 7 +8.18%B 2 O 3 .When the experiment was performed, the sample was contained in an alumina crucible with the size of 10 mm OD×10 mm ID×11 mm together with a suitable mount of fluxing agent. The vacuum chamber was evacuated to 2×10 −4 Pa and backfilled with argon gas. The sample was melted a...

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Dual purpose pyrometer for temperature and solidification velocity measurement

Abstract: A twopyrometer method of measuring substrate temperatures

Cited by 43 publications

References 9 publications

Solidification behavior and microstructural evolution during laser beam—material interaction

Solidification behavior and microstructural evolution during laser beam—material interaction

Atomistic and continuum modeling of dendritic solidification

Rapid dendrite growth in quaternary Ni-based alloys

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