Tb_(0.3)Dy_(0.7)Fe_(1.95-x)Ti_x(x=0,0.03,0.06,0.09)合金的微观组织与磁致伸缩性能

MICROSTRUCTURE AND MAGNETOSTRICTION OF THE Tb_(0.3)Dy_(0.7)Fe_(1.95-x)Ti_x(x=0,0.03,0.06,0.09) ALLOYS

利用高真空非自耗电弧炉制备了Tb_(0.3)Dy_(0.7)Fe_(1.95-x)Ti_x(x=0,0.03,0.06,0.09)合金,系统研究了不同Ti含量Tb_(0.3)Dy_(0.7)Fe_(1.95-x)Ti_x合金的晶体结构、微观组织、磁致伸缩性能及它们之间的关系.结果表明:添加Ti后的Tb_(0.3)Dy_(0.7)Fe_(1.95-x)Ti_x合金基体相仍为MgCu_2型Laves相结构,Ti取代了Tb_(0.3)Dy_(0.7)Fe_(1.95)合金中比其自身半径大的稀土原子Tb和Dy而使晶格常数减小.添加Ti后,初生相TiFe_2的形成使得凝固液体中富含R(R=Tb,Dy)从而抑制了有害相RFe_3的生成,Ti在基体相RFe_2中和富R相中都可溶解,分别形成了(R,Ti)Fe_2基体相和富(R,Ti)相.Ti的添加量对磁致伸缩性能的影响很大,当x=0.03时,Ti的添加使磁致伸缩性能较Tb_(0.3)Dy_(0.7)Fe_(1.95)母合金提高幅度最大,但当x=0.09时,由于顺磁相TiFe_2和富(R,Ti)相的析出对磁致伸缩性能不利,但相对于Tb_(0.3)Dy_(0.7)Fe_(1.95)母合金也有少量提高.

The Tb0.3Dy0.7Fei1.95-xTix（x=0,0.03,0.06,0.09） alloys were prepared by high-vacuum non-consumable arc melting furnace.The crystal structure,microstructure,magnetostriction and their relationships of the Tb0.3Dy0.7Fe1.95-xTix（x=0,0.03,0.06,0.09） alloys were systematically studied.The results demonstrated that the matrix phase of the Tb0.3Dy0.7Fe1.95-xTix（x=0.03,0.06, 0.09） alloys consisted predominantly of the Laves phase with MgCu2 structure.After Ti addition,the lattice parameter of the Laves phase in the alloys was decreased by substituting rare earth elements Tb and Dy,and the formation of the TiFe2 phase as the primary phase made the solidifying liquid become rich in rare earths and suppressed the formation of the deleterious RFe3（R=Tb and Dy） phase.Ti was found to be soluble in the matrix RFe2 and R-rich phases and formed the matrix （R,Ti）Fe2 and（R,Ti）-rich phases.The concentration of Ti affected the magnetostriction significantly. The improvement in magnetostriction was maximum for the Ti-added alloys with a low concentration of the Ti（x=0.03） as compared to the parent alloy Tb0.3Dy0.7Fe1.95.However,the decrease in magnetostriction at a higher concentration（x=0.09） was due to the formation of paramagnetic phases TiFe2 and（R,Ti）-rich.Whereas the magnetostriction had little improvement as compared to the parent alloy Tb0.3Dy0.7Fe1.95.