PDF《Trans. Nonferrous Met. Soc. China》

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Nonferrous Met. Soc. China 24(2014) 712?717 Fe75Zr3Si13B9 magnetic materials prepared by spark plasma sintering Xing-hua WANG1 , Ge WANG1 , Yu-ying ZHU1 , Jin-feng BAO1 , Xiong-fei DU1 , Qiang LI1,2,3 1. National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004, China;

2. National Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;

3. College of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, China Received

17 April 2013;

accepted

5 July

2013 Abstract: Fe75Zr3Si13B9 magnetic amorphous powders were fabricated by mechanical alloying. Bulk amorphous and nanocrystalline alloys with

20 mm in diameter and

7 mm in height were fabricated by the spark plasma sintering technology at different sintering temperatures. The phase composition, glass transition temperature (Tg), onset crystallization temperature (Tx), peak temperature (Tp) and super-cooled liquid region (ΔTx) of Fe75Zr3Si13B9 amorphous powders were analyzed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The phase transition, microstructure, mechanical properties and magnetic performance of the bulk alloys were discussed with X-ray diffractometer, scanning electron microscope (SEM), Gleeble

3500 and vibration sample magnetometer (VSM), respectively. It is found that with the increase in the sintering temperature at the pressure of

500 MPa, the density, compressive strength, micro-hardness and saturation magnetization of the sintering samples improved significantly, the amorphous phase began to crystallize gradually. Finally, the desirable amorphous and nanocrystalline magnetic materials at the sintering temperature of 863.15 K and the pressure of

500 MPa have a density of 6.9325 g/cm3 , a compressive strength of 1140.28 MPa and a saturation magnetization of 1.28 T. Key words: mechanical alloying;

amorphous and nanocrystalline alloys;

saturation magnetization;

spark plasma sintering

1 Introduction Spark plasma sintering (SPS) technology developed in the 1990s is a energy-conservation, environmental protection and novel highly-efficient technology for preparing materials, which combines plasma activation, hot pressing and resistance heating, as known as the plasma activated sintering or pulse current hot pressing sintering [1?3]. Because of rapid sintering speed, low sintering temperature, special sintering mechanism, simple and convenient operation, without powder preformed etc, SPS has been recognized as the most competitive and promising technique to successfully consolidate bulk nano-materials with high density, nanocrystalline and clean interface, and widely used for preparation or research of ceramics, intermetallics, functional gradient materials and composites [4?6]. The large DC pulsed sintering current is applied through the electrodes at the top and bottom punches of the die and also flowed through the compacted powders. The Joule heat is generated instantaneously between the surfaces of particles, which produces local high temperature and achieves formation and diffusion of the sintering neck. Meanwhile, the pulse current causes discharge effect among particles, which can purify the surface of particles, restrict the growth of grain and realize the densification under high pressure [7,8]. Since the '

Finemet'

alloys were fabricated in amorphous matrix through heat treatment by YOSHIZAWA et al [9], Fe-based nanocrystalline soft magnetic materials with excellent soft magnetic and mechanical properties have become a hot research, such as fabrication of '