Static magnetic and microwave absorption properties of FeCo/Al sub(2)O sub(3) composites synthesized by high-energy ball milling method

• Published in: Journal of physics. D, Applied physics Applied physics, 2014-02, Vol.47 (6), p.1-6
• Main Authors: Shang, Rongxiang, Zhang, Yi, Yan, Longgang, Xia, Haiyan, Liu, Qingfang, Wang, Jianbo
• Format: Article
• Language: English
• Subjects: Alloy powders; Aluminum oxide; Ball milling; Insulators; Intermetallic compounds; Microwave absorption; Noise levels; Reflection; Saturation (magnetic)
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/47/6/065001

FeCo/Al sub(2)O sub(3) composites were prepared by mechanochemical synthesis route using a mixture of Fe sub(2)O sub(3), Co sub(3)O sub(4) and Al as the starting materials. FeCo alloy can be obtained in a short time in contrast to the traditional method by means of milling Fe and Co powders directly. Most FeCo/Al sub(2)O sub(3) composites can be formed when ball milling time has achieved 15 min. As the milling time increases, the saturation magnetization (M sub(s): magnetic moment per unit mass) and coercive force (H sub(c)) of FeCo/Al sub(2)O sub(3) composites increase gradually. The FeCo/Al sub(2)O sub(3) composites exhibit a value of M sub(s) of 98.5 emu g super(-1) and H sub(c) of 350 Oe finally. The products with ball milling time 15 min and 30 min provided better microwave absorption performances in the frequency ranges of 8.6-18 GHz and 2.5-6.5 GHz for an absorber thickness of 1.2-2.2 mm and 2.1-4.9 mm, respectively. An optimal reflection loss of -43.1 dB can be obtained at 4.1 GHz with an absorber thickness of 3.1 mm. The good microwave absorption performances result from an appropriate impedance matching due to the insulator Al sub(2)O sub(3) dispersed around FeCo alloy.