DocumentCode :
1362597
Title :
Structural Stability and Magnetic Properties of the TbCu _{7} -Type SmCo _{x - 0.4} Ti
Author :
Jiang, Chengbao ; Yao, Zan
Author_Institution :
Sch. of Mater. Sci. & Eng., Beijing Univ. of Aeronaut. & Astronaut., Beijing, China
Volume :
46
Issue :
1
fYear :
2010
Firstpage :
10
Lastpage :
14
Abstract :
We have studied the composition dependence, thermal stability, long-term stability at 500°C, and magnetic properties of the nanostructural TbCu7-type (1:7) Sm-Co-Ti alloys. We prepared the SmCox-0.4Ti0.4 alloys with a wide composition range from x = 5.0 to x = 8.5 by high-energy ball-milling, followed by annealing at 700-1100°C for 2 h. After annealing at 700°C, the powders with x = 7.0-8.5 showed a single 1:7 structure, while the powders with x = 5.0-6.5 presented the 1:7 plus CaCu5-type (1:5) structure. At an annealing temperature higher than 800°C, a minor Th2Zn17-type (2:17) phase precipitated in the matrix of the 1:7 phase. Intrinsic coercivity iHc exhibits a maximum of 2.3 T at room temperature and 0.4 T at 500°C in the x = 7.0 samples annealed at 700°C. The temperature coefficient of iHc seems stable as the Sm/Co ratio changes from 1/6.5 to 1/7.5. The coercivity decreased with increasing annealing temperature Ta, from 2.3 T at Ta = 700°C to 1.3 T at Ta = 1100°C, which is mainly attributed to the grain growth from 35 nm for Ta = 700°C to 1 ¿m for Ta = 1100°C. After holding at 500°C for up to 360 h, the microstructure and magnetic properties of the 1:7-type nanograin alloys remained almost unchanged, indicating a structurally and magnetically long-term stabilization at the potential high-temperature application environment.
Keywords :
annealing; ball milling; cobalt alloys; coercive force; grain growth; nanostructured materials; permanent magnets; samarium alloys; thermal stability; titanium alloys; SmCox-0.4Ti0.4; annealing; ball milling; coercivity; grain growth; magnetic flux density 1.3 T; magnetic flux density 2.3 T; nanostructural alloys; powders; structural stability; temperature 293 K to 298 K; temperature 500 degC; temperature 700 degC to 1000 degC; thermal stability; time 2 h; Annealing; Coercive force; Magnetic properties; Magnets; Metastasis; Samarium alloys; Structural engineering; Temperature; Thermal stability; Titanium alloys; Curie temperature; Sm-Co based permanent magnets; high-temperature application; long-term thermal stablility; magnetic properties;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/TMAG.2009.2028021
Filename :
5357514
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