深过冷铁磁性Co基合金中磁有序对液态金属结构及凝固行为的影响

In general, magnetic transition occurred in solid matter, there is no visible effect of magnetic ordering on crystal structure because the atom was restricted in solid. It is common knowledge that bulk metallic melts can be undercooled below their melting temperatures, if the metallic metal undercooled below Curie temperature and the magnetic transition occurred in liquid metal, the effect of magnetic ordering on structure of liquid metal cannot be neglect due to the atom freedom mobile in liquid. It is very interesting to investigate the effect of magnetic ordering on liquid structure. Co base alloys shows high Curie temperature and easily be undercooled, they are the optimal system for study the effect of magnetic ordering on liquid structure. In present work, Co base alloys will be undercooled below Curie temperature by molten glasses denucleation or Ultrasonic levitation melting, and the liquid structure will be measured by XRD or neutron scattering. The effect of magnetic ordering on liquid structure and solidification behavior will be discussed.

通常情况下，顺磁-铁磁转变发生于固态物质中，由于固态中原子受到约束，磁有序结构对晶体结构无明显影响。众所周知，金属材料可被过冷到熔点之下数百K凝固，若合金被过冷到液态居里温度之下，磁性转变发生于液态金属中，此时，由于液态合金中原子移动较为自由，磁有序对液态金属结构的影响不容忽视，研究磁有序结构对液态金属结构的影响具有重要的理论意义。Co基合金具有高居里温度、易过冷等特点，是研究磁有序结构对液态金属结构影响的最理想合金体系。基于此，申请人提出分别采用可控降温的玻璃熔体净化深过冷技术和超声悬浮熔炼，将Co基合金过冷到居里温度之下，采用XRD或中子散射测定不同温度下的液态金属结构，获得液态金属的结构因子、径向分布函数及双体分布函数，探讨磁有序对液态金属结构的影响规律，阐明其物理机制。结合形核、相选择、磁畴结构及微观组织结构分析探讨磁有序结构对凝固行为的影响。