非晶合金CoFeNbSiB的纳米晶化及磁性

NANOCRYSTALLIZATION AND MAGNETIC PSOPERTIES OF CoFeNbSiB AMORPHOUS ALLOYS

研究了Ｃｏ６８Ｆｅ７Ｎｂ５Ｓｉ１２Ｂ８和Ｃｏ６４Ｆｅ１１Ｎｂ５Ｓｉ１２Ｂ５两种非晶合金在４００～５８０℃温度间等温退火１ｈ后的纳米晶化行为和磁性．结果表明，在４５０～５６０℃退火ｌｈ后，在两种非晶合金的基体上均析出了单一晶相ｂｃｃ结构的α－Ｆｅ（Ｃｏ）固溶体当退火温度（Ｆａ）低于４７０℃时，合金具有很好的软磁性能；Ｔａ为５４０～５６０℃，矫顽力明显增加，在弱场下磁化强度变得很低；当Ｔａ≥５８０℃时，新的晶化相Ｃｏ－Ｂ，Ｆｅ－Ｂ及其它化合物析出，磁性变得比较软这可能是由于具有ｂｃｃ结构的α－Ｆｅ（Ｃｏ）相具有大的磁致伸缩．

Nanocrystallization behavior and magnetic properties of amorphous Co68Fe7Nb5Si12B8 and Co64FellNb5Si12B8 alloys isothermally annealed in the temperature range of 400-580℃ have been investigated. Results showed that bee α-Fe(Co) solid solution with grain size of about 10nm is precipited in the amorphous matrix for the two kinds of alloy annealed in temperature range of 450-560 ℃ for an hour. When annealed temperature (Ta) is lower than 470℃, the soft magnetic properties of alloys are rather good, but after annealing in temperature range of 540-560℃, the coercivity increases abruptly and the magnetization in the weak field becomes very low. When Ta≥580 ℃, the new crystalline phases such as Co-B. Fe-B and other compounds precipitate; meanwhile the magnetic properties become softer. This unusual experimental result has been explained by the large magnetostriction of the bcc a-Fe(Co)phase.