Heat and mass transfer characteristics during rapid solidification of Fe-Cu peritectic alloys |
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Authors: | JinFeng Xu FuPing Dai BingBo Wei |
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Institution: | (1) Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072, China;(2) School of Materials Science and Engineering, Xi’an University of Technology, Xi’an, 710048, China |
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Abstract: | The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and
temperature fields during rapid solidification, which is verified by rapid quenching experiments. It is found that a large
temperature gradient exists along the vertical direction of melt puddle, whereas there is no obvious temperature variation
in the tangent direction of roller surface. After being sprayed from a nozzle, the alloy melt changes the magnitude and direction
of its flow and velocity rapidly at a height of about 180 μm. The horizontal flow velocity increases rapidly, but the vertical
flow velocity decreases sharply. A thermal boundary layer with 160–300 μm in height and a momentum boundary layer with 160–240
μm in thickness are formed at the bottom of melt puddle, and the Reynolds number Re is in the range of 870 to 1070 in the
boundary layer. With the increase of Re number, the cooling rate increases linearly and the thickness of thermal boundary
layer increases monotonically. The thickness of momentum boundary layer decreases slowly at first, then rises slightly and
decreases sharply. If Re < 1024, the liquid flow has remarkable effects on the microstructure formation due to dominant momentum
transfer. The separated liquid phase is likely to form a fiber-like microstructure. If Re>1024, the heat transfer becomes
dominating and the liquid phase flow is suppressed, which results in the formation of fine and uniform equiaxed microstructures.
Supported by the National Natural Science Foundation of China (Grant Nos. 50121101 and 50395105) |
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Keywords: | peritectic alloy liquid phase separation fluid flow heat transfer rapid solidification |
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