Mechanical and magnetostrictive properties of Tb0.36Dy0.64（Fe1-xMnx）1.9 alloys

The magnetization, magnetostriction and compressive strengths of arc-cast polycrystalline and directionally solidified Tb0.36Dy0.64（Fe1-xMnx）1.9 （x=0, 0.05, 0.10, 0.15, 0.20） rods were investigated by VSM, standard strain gauge method and compressive tests, respectively. The results show that the magnetostriction λs, saturation magnetization Ms and magnetocrystalline anisotropy constant K1 decrease with increasing the Mn concentration. The optical micrographs and XRD patterns show that the Tb0.36Dy0.64（Fe1-xMnx）1.9 alloys are composed of MgCu2-type Laves phase as matrix and a small amount of rare-earth rich phase. It is found that the distribution of the rare-earth rich phase has an important effect on mechanical property of Tb0.36Dy0.64（Fe1-xMnx）1.9 samples. For the arc-cast samples, smaller equal-axial grains are arranged irregularly, which results in higher compressive strengths. However, the rare-earth rich phase is arranged as parallel arrays in the directionally solidified samples, which leads to smaller compressive strengths.