Model of temperature field for the preparation process of melt-spun NdFeB powders
来源期刊：Journal of Rare Earths2014年第6期
论文作者：赖彬 李岩峰 王会杰 李安华 朱明刚 李卫 张跃
文章页码：514 - 520
摘 要：Melt-spun ribbons which are the important raw material for hot-deformed magnets can be prepared by single-roller melt-spinning. In order to prepare well-structured ribbons, the model of temperature field for single-roller melt-spinning process was constructed in this work. The heat conduction in this process was simplified as one dimensional heat conduction problem. It was shown by modeling that, the temperature field in the melt-spinning before solidification in this model could be described as this equation T（x,t）=Tmoexp[–k（x–x0）–k2αt]+T0. The temperature T（x,t） of the alloy melts decreased with increased position x and cooling time t exponentially from the wheel-free surface to the wheel-side surface. The constant k determined the decrease speed of alloy temperature T（x,t）, which was proportional to the interfacial heat transfer coefficient h and the interfacial area of heat conduction A0, but inversely proportional to the thermal conductivity K. x0 was the thickness of the alloy melt. With increased x0, the temperature difference between wheel-free surface and the wheel-side surface became larger, which would lead to larger difference in grain size. In experiments, the influence of melt-spinning process parameters on the temperature field model was discussed, such as cooling roller materials, wheel speed, and so on. Melt-spun ribbons prepared by single-roller melt spinning at different wheel speed were investigated and magnetic properties of die-upset magnets from melt-spun ribbons on different cooling roller were analyzed. The variation of grain size in the depth direction consisted with temperature field model. This model provided directions for the preparation of melt-spun ribbons with uniformly distributed fine grains, which were very necessary for producing hot-deformed magnets with high magnetic performance.
赖彬1,2，李岩峰1，王会杰1，李安华1，朱明刚1，李卫1，张跃2
1. Division of Functional Materials, Central Iron & Steel Research Institute2. School of Materials Science and Engineering, University of Science and Technology Beijing
摘 要：Melt-spun ribbons which are the important raw material for hot-deformed magnets can be prepared by single-roller melt-spinning. In order to prepare well-structured ribbons, the model of temperature field for single-roller melt-spinning process was constructed in this work. The heat conduction in this process was simplified as one dimensional heat conduction problem. It was shown by modeling that, the temperature field in the melt-spinning before solidification in this model could be described as this equation T（x,t）=Tmoexp[–k（x–x0）–k2αt]+T0. The temperature T（x,t） of the alloy melts decreased with increased position x and cooling time t exponentially from the wheel-free surface to the wheel-side surface. The constant k determined the decrease speed of alloy temperature T（x,t）, which was proportional to the interfacial heat transfer coefficient h and the interfacial area of heat conduction A0, but inversely proportional to the thermal conductivity K. x0 was the thickness of the alloy melt. With increased x0, the temperature difference between wheel-free surface and the wheel-side surface became larger, which would lead to larger difference in grain size. In experiments, the influence of melt-spinning process parameters on the temperature field model was discussed, such as cooling roller materials, wheel speed, and so on. Melt-spun ribbons prepared by single-roller melt spinning at different wheel speed were investigated and magnetic properties of die-upset magnets from melt-spun ribbons on different cooling roller were analyzed. The variation of grain size in the depth direction consisted with temperature field model. This model provided directions for the preparation of melt-spun ribbons with uniformly distributed fine grains, which were very necessary for producing hot-deformed magnets with high magnetic performance.
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