摘要
本文研究了三元Fe_(73)B_(22)Nb_5合金快速凝固过程中的组织演变规律,系统分析了凝固组织与合金微观力学性能以及室温磁学性能的关联机制.实验测定出合金固相线温度为1410 K,液相线温度为1525 K.在近平衡凝固条件下,初生Fe_(2)B相率先析出,剩余液相形成(FeNbB+αFe+Fe_(2)B)三元共晶.自由落体过程中合金液滴的过冷度随其直径的减小呈指数关系单调递增,最大过冷度可达352 K (0.23T_L).实验表明,基于过冷度对相组成的强烈影响,可以实现对合金微观力学性能和磁学性能的调控.随着过冷度的增大,初生Fe_(2)B相的生长被抑制,共晶组织体积分数逐渐增加.三元共晶中的FeNbB相对合金的微观力学性能有着显著的强化作用,其硬度为15.1 GPa,杨氏模量为170.7 GPa.深过冷条件下,液态合金快速凝固全部形成非规则三元共晶组织.溶质截留效应使得Nb元素分布更为均匀,FeNbB相体积分数明显增大,合金硬度最高可达1197 HV,矫顽力则由79 Oe锐减至54 Oe.
The microstructure evolution of ternary Fe_(73)B_(22)Nb_(5) alloy during rapid solidification was studied under free fall conditions. The effectsof alloy microstructure on its micromechanical and magnetic properties were examined systematically. The liquidus and solidustemperatures were measured as 1525 and 1410 K, respectively. Under a near-equilibrium solidification condition, the primary Fe2Bphase forms preferentially, and then the remnant alloy melt solidified into a ternary (FeNbB+αFe+Fe2B) eutectic structure. Thediameter of the alloy droplets used in containerless processing by drop tube ranged from 90 to 1030 μm. Theoretical calculationsshowed that liquid undercooling and cooling rates increased exponentially with the decrease in droplet diameter. The maximumundercooling and cooling rate reached 352 K (0.23TL) and 7.25 × 104 K s−1. The growth of the primary Fe2B phase was reduced whenalloy undercooling was sufficiently high, and ternary eutectic microstructures took over as the dominating microstructures. Theeutectic FeNbB phase revealed a significant strengthening effect on the micromechanical property of this alloy, and its hardness andYoung’s modulus attained 15.1 and 170.7 GPa. The solute trapping effect resulted in a uniform distribution of Nb elements and ahigher volume fraction of the FeNbB phase. As a result, the alloy hardness achieved a maximum of up to 1197 HV. Additionally, grainrefinement enhanced the soft magnetic property, while alloy coercivity significantly reduced the alloy coercivity from 79 to 54 Oe.
作者
糜晓磊
胡亮
魏炳波
MI XiaoLei;HU Liang;WEI BingBo(School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710072,China)
出处
《中国科学：技术科学》
EI
CSCD
北大核心
2024年第2期304-314,共11页
Scientia Sinica(Technologica)
基金
国家重点研发计划(编号:2021YFA0716301)
国家自然科学基金(批准号:52088101)
陕西省自然科学基金(编号:2023JCJQ30)资助项目。
关键词
Fe-B-Nb合金
快速凝固
组织控制
力学性能
磁学性能
Fe-B-Nb alloy
rapid solidification
microstructure control
mechanical property
magnetic property
