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利用高真空非自耗电弧炉制备了Tb_0.3Dy_0.7Fe_1.95-xTi_x (x=0, 0.03, 0.06, 0.09) 合金, 系统研究了不同 Ti含量Tb_0.3Dy_0.7Fe_1.95-xTi_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_0.3Dy_0.7Fe_1.95-xTi_x合金基体相仍为MgCu$_{2}$型Laves相结构, Ti取代了 Tb_0.3Dy_0.7Fe_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TiFe₂的形成使得凝固液体中富含R (R=Tb, Dy)从而抑制了有害相RFe₃的生成, Ti在基体相RFe₂中和富$R$相中都可溶解, 分别形成了(R, Ti)Fe₂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_0.3Dy_0.7Fe_1.95母合金提高幅度最大, 但当x=0.09时, 由于顺磁相TiFe₂和富(R, Ti)相的析出对磁致伸缩性能不利, 但相对于Tb_0.3Dy_0.7Fe_1.95母合金也有少量提高.

The Tb_0.3Dy_0.7Fe_1.95-xTi_x ($x$=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 Tb_0.3Dy_0.7Fe_1.95-xTi_x ($x$=0, 0.03, 0.06, 0.09) alloys were systematically studied. The results demonstrated that the matrix phase of the Tb_0.3Dy_0.7Fe_1.95-xTi_x (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 Tb_0.3Dy_0.7Fe_1.95. 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\linebreak Tb_0.3Dy_0.7Fe_1.95.