B元素添加对Co-Zr-Mo合金薄带的磁性能及结构的影响

Effects of B additive on structure and magnetic properties of Co-Zr-Mo alloys

利用X射线和磁性测量研究了Co_(77)_Zr(18-x)Mo_5B_x合金薄带的结构和磁性.实验发现,在Co-Zr-Mo合金中添加适当含量的B,可以使其矫顽力显著提高,当x=2.0时,制备出具有迄今为止Co-Zr基永磁合金最大矫顽力H_c=7.0 kOe(1 Oe=79.5775 A/m)的快淬薄带.随着B元素添加,Co_(77)Zr_(18-x)Mo_5B_x合金薄带的晶粒逐渐细化,并根据Henkel plot模型计算得出软磁相fcc-Co与硬磁相Co_5Zr相之间的交换耦合作用逐渐增强.合金薄带的矫顽力主要受硬磁相Co_5Zr相的晶粒尺寸控制,并随着晶粒尺寸的减小先升高后降低.另一方面,Co_(77)Zr_(18)Mo_5合金薄带的矫顽力机理为反磁化核形核模型,添加B元素之后矫顽力机理变为畴壁钉扎模型.通过X射线衍射和热磁分析发现,B元素并没有进入到Co_5Zr相的晶格中,而是存在于非晶相中.

The phases and magnetic properties of Co77Zr18-xMo5Bx （x = 1.0, 1.5, 2.0, 2.5, and 4.0） are studied by X-ray diffraction analysis and magnetic measurements. Proper addition of Ti could improve the magnetic properties of Co-Zr alloy significantly. The largest value of Hc ---- 7.0 kOe （10e = 79.5775 A/m） is obtained in the Co77Zr18-xMo5Bx melt-spun ribbon. The grain size of Co5Zr phase decreases with the increase of B content, which contributes significantly to the enhancement of exchange-coupling effect. The coercivity values of the Co77Zr18-xMo5Bx （x =1.0, 1.5, 2.0, 2.5） melt-spun ribbons are affected mainly by the grain size of the Co5Zr phase. The coercivity value first increases and then decreases with the decrease of the Co5Zr phase. On the other hand, the coercivity mechanisms of Co77Zr18-xMo5B （x = 1.0, 1.5, 2.0, 2.5） melt-spun ribbons are found to be of the pinning type.