Model of temperature field for the preparation process of melt-spun NdFeB powders

• Published in: Journal of rare earths Vol. 32; no. 6; pp. 514 - 520
• Main Author: 赖彬 李岩峰 王会杰 李安华 朱明刚 李卫 张跃
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2014
• Subjects: Conduction; Heat conduction; Heat transfer; Mathematical models; Melt spinning; melt-spun ribbon; model of temperature field; nanocrystalline; NdFeB; Rare earth metals; rare earths; Ribbons; Temperature distribution; 制备工艺; 温度场模型; 热传导问题; 热变形磁体; 熔纺; 界面热传导; 车轮速度; 钕铁硼粉末; model of temperature field; nanocrystalline; melt-spun ribbon; NdFeB; rare earths
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/S1002-0721(14)60101-0

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 equa-tionT（x,t）=Tmoexp[-k（x-x0）-k2αt]＋T0. The temperatureT（x,t） of the alloy melts decreased with increased positionx and cooling timet exponentially from the wheel-free surface to the wheel-side surface. The constantk determined the decrease speed of alloy tempera-tureT（x,t）, which was proportional to the interfacial heat transfer coefficienth and the interfacial area of heat conductionA0, but in-versely proportional to the thermal conductivityK.x0 was the thickness of the alloy melt. With increasedx0, the temperature differ-ence between wheel-free surface and the wheel-side surface became larger, which would lead to larger difference in grain size. In ex-periments, 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 investi-gated 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.