论文部分内容阅读
The main types of defect in the (Tb_(0.3)Dy_(0.7))Fe_(1.95) alloys with the “one-step” directional solidification process were investigated. The effect of the dendrite, grain boundaries, twin boundaries, and REFe_3 precipitates on the magnetostrictive response of the (Tb_(0.3)Dy_(0.7))Fe_(1.95) alloys was analyzed respectively. The experiment results demonstrate that the dendrite, twin boundaries, and REFe_3 precipitates can be avoided by modifying alloying ingredient, solidification parameters and annealing technique. The dendritic growth front often leads to dendrite sheet, rare earth-rich phase, and twin boundaries. The lower proportion of rare earth, or slow solidification rate, results in the occurrence of REFe_3 precipitatates. It is vital for diminishing the defects to control the undercooling of solid-liquid interface at (2.4～5.1)×10~4 K·s·cm~(-2) so that the crystal grows in cellular growth front.
The main types of defects in the (Tb_ (0.3) Dy_ (0.7)) Fe_ (1.95) alloys with the “one-step ” directional solidification process were investigated. The effect of the dendrite, grain boundaries, twin boundaries, and REFER_3 precipitates on the magnetostrictive response of the (Tb_ (0.3) Dy_ (0.7)) Fe_ (1.95) alloys were analyzed respectively. The experiment results demonstrate that the dendrite, twin boundaries, and REFe_3 precipitates can be avoided by modifying alloying ingredients, solidification parameters and annealing technique. The dendritic growth front often leads to dendrite sheet, rare earth-rich phase, and twin boundaries. The lower proportion of rare earth, or slow solidification rate, results in the occurrence of REFe_3 precipitatates. It is vital for diminishing the defects to control the undercooling of solid-liquid interface at (2.4-5.1) × 10-4 K · s · cm -2 so that the crystal grows in cellular growth front.