Melting Characteristics of Equiaxed NH₄Cl Crystals Settling in Superheated NH₄Cl-H₂O Melts

Abstract:

The influence of equiaxed crystal movements in a superheated environment on the melt kinetics of the equiaxed crystals was experimentally investigated by observation of the settling and melting behaviors of NH4Cl equiaxed crystals in its aqueous solution. The experimental set-up composed of the settling tubes, water bath and video capture device, where NH4Cl equiaxed crystals were acquired in a cooling zone and then introduced into the superheated settling tubes filling with NH4Cl-H2O model alloy, and the morphologies of the equiaxed crystals were video captured for further analysis. Two kinds of morphology evolution have been observed, and the difference was related with typical spinning movements of the equiaxed crystals during their sedimentation. Changes of the length of six primary dendrite arms have been measured; the results were compared with the calculated melting rate for equiaxed crystals without any convection. It has been shown that the convection induced by the sedimentation imposes a strong influence on the melting kinetics of the equiaxed crystals.

• Periodical: Advanced Materials Research (Volumes 538-541)
• Pages: 2444-2447
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.538-541.2444
• Online since: June 2012
• Authors: Peng Zhou, Meng Wang, Lei Chen, Feng Qiu, Wei Dong Huang, Jia Liang Zhang
• Keywords: Ammonium Chloride, Equiaxed Crystal, Melting Rate, Morpholoy, Settling

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