Synthesis of Tb-Dy-Fe Alloy by Mechanical Alloying and Its Consolidation

Abstract

The formation process of Th-Dy-Fe giant magnetostrictive alloy made by the mechanical alloying (MA) and the spark plasma sintering (SPS) was investigated. The MA was performed in a planetary ball mill using three elemental powders. The powders were prepared by the mixing of (Tb_xDy_1-x)Fe_y (x=0-1.0, y=1.6, 1.8, 2.0). The MA powders were consolidated by SPS method. From the result of X-ray analysis, the structure of the MA powder was close to amorphous after milling for 360ks. During SPS, the structure of sample heated below 773K was not change from that of room temperature. On the other hand, the structure of sample heated above 773K was change to intermetallic compounds such as TbFe₂, DyFe₂ and Dy₆Fe₂₃. From the result of X-ray analysis, the amount of Dy₆Fe₂₃ phase, which is not useful for magnetostrictive effect, was smallest after SPS by using the composition of (Tb_0.5Dy_0.5)Fe_1.8 powders. The relative density of sample after SPS at 1073K was about 98%. It was found that the composition of (Tb_0.5Dy_0.5)Fe_1.8 and sintering temperature of 1073K were the best condition for making magnetostrictive alloy by using MA and SPS.