钕铁硼速凝薄片中α-Fe析出临界冷却速度的估算  

Estimation of Critical Cooling Rate of α-Fe Precipitate in Nd-Fe-B Cast Strips

作　　者：王景代[1] 谢发尹[1] 孟宇[1] 张华霞[1] 吴昌新[1] 孙传祺[1] 

机构地区：[1]中航工业北京航空材料研究院熔铸中心,北京100095

出　　处：《中国稀土学报》2014年第3期311-315,共5页Journal of the Chinese Society of Rare Earths

摘　　要：采用FMI-I-600-R-C型真空感应熔炼速凝炉制备了不同厚度的钕铁硼速凝薄片,并用螺旋测微器从中分别选取厚度为0.2,0.3,0.4,0.5,0.6和0.7 mm的速凝薄片,采用扫描电子显微镜对各个薄片进行微观组织和微区成分分析,发现厚度为0.2～0.4 mm的速凝薄片中没有α-Fe析出,而厚度超过0.4 mm的速凝薄片靠近自由面处均存在α-Fe,表明冷却速度沿着厚度方向是逐渐降低的。当厚度超过0.4 mm时,靠近自由面处的冷却速度过低而不能完全抑制α-Fe的生成,以0.4 mm厚速凝薄片为研究对象,结合热传导理论和凝固理论,应用数学解析法计算了α-Fe在钕铁硼速凝薄片中析出的临界冷却速度。Nd-Fe-B cast strips with different thickness were made by NO. FMI-I-600-R-C vacuum induction melting rapid solidification furnace,and the strips with thickness of 0. 2,0. 3,0. 4,0. 5,0. 6 and 0. 7 mm were selected by micrometer. The microstructures of the strips and the composition of regions within the strips were analyzed by scanning electron microscopy. The results showed that there was no precipitation of α-Fe in the strips with thickness in the range of 0. 2 ～ 0. 4 mm,however,α-Fe precipitated in the free side of the strips when the thickness over 0. 4 mm. It was concluded that the cooling rate was decreasing with increasing the thickness of strips and the cooling rate was too low to prohibited the precipitation of α-Fe when the thickness of the strips exceed 0. 4mm. In this paper,the strip with thickness of 0. 4 mm was studied. Combined heat conduction theory and solidification theory, the critical cooling rate of α-Fe precipitated in Nd-Fe-B cast strips was estimated by mathematical analysis method.

关 键 词：钕铁硼 Α-FE 临界冷却速度 稀土 

分 类 号：TF845[冶金工程—有色金属冶金]