Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11001718 | Physica B: Condensed Matter | 2019 | 6 Pages |
Abstract
There is a close relationship between the magnetic properties of alnico permanent magnetic alloys and the nano-scaled spinodally decomposed structure which results from various heat treatment cycles. In this paper, different heat treatment cycles are employed to cast alnico 8 alloys with composition 32.3Fe-37.5Co-13.7Ni-6.2Al-5.8Ti-3.4Cu-0.2Zr-0.1S-0.8Nb. It is observed that magnetic field treatment at high temperature for specific time is the most effective method to obtain better microstructure and magnetic properties. The mosaic structures consisting of Fe-Co phase and Al-Ni rich phase are best separated during thermomagnetic treatment for 4-5â¯min and refined during low temperature treatments. The bias growth of the ferromagnetic phase does not develop in absence of magnetic field, and hence the phases are not refined and separated completely. This produces isotropic alnico alloys with low magnetic properties. However, continuous cooling of the alloys in magnetic field followed by isothermal treatment without magnetic field provides moderate magnetic properties. Treatment at high temperatures in field and without field for longer time leads to the coarsening of spinodal phases and poor magnetic properties. The optimum magnetic properties of Hcjâ¯=â¯1.7â¯kOe, Brâ¯=â¯8.0â¯kGs and (BH)maxâ¯=â¯5.02 MGOe are attributed to the refined microstructure of the thermomagnetically treated alloys.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Sajjad Ur Rehman, Qingzheng Jiang, Weikai Lei, Kai Liu, Liangliang Zeng, Mahpara Ghazanfar, Tahir Ahmad, Renhui Liu, Shengcan Ma, Zhenchen Zhong,