定向凝固TbDyFe合金的取向、组织和磁致伸缩性能

THE PREFERRED ORIENTATION, MICROSTRUCTURE AND MAGNETOSTOSTRION IN DIRECTIONALLX SOLIDIFIED TbDyFe ALLOYS

采用JSL－500区域熔化真空定向凝固装置，对TbDyFe超磁致伸缩合金定向凝固轴向择优取向、组织和磁致伸缩性能的研究表明：温度梯度GL≈700K／cm基本不变的条件下，当晶体生长速度V1mm／min时，晶体以平面晶方式生长；16mm/min时，以胞状晶方式生长；V=8─12mm／min时，晶体按胞核晶方式生长（胞状晶向树枝晶转变的初始阶段）；当V＞15mm／min时，晶体按发达的树枝晶方式生长．保持V＝12mm／min不变，当GL≈1000K／cm时，晶体又以胞状品方式生长；GL≈400K／cm时，以发达的树枝晶方式生长平面晶和胞状晶生长的样品，其轴向择优取向为＜110＞取向，磁致伸缩没有压力效应，性能偏低；胞枝晶方式生长的样品轴向择优取向为＜112＞取向，磁致伸缩性能优越，10MPaN压应力下，平行于外磁场方向的饱和磁致伸缩系数λ最大值达到0．00175；发达树枝晶生长的样品，轴向＜112＞择优取向程度减弱，磁致伸缩性能下降。

The device of zone melting directional solidification has been used to investigate the preferred orientation, microstructure and magnetostriction of Tb0.3Dy0.7(Fe, M)1.95 (M=Al,Mn, B) metallic compound. When the temperature gradient GL≈700 K/cm, the growth velocity V mm/min, the crystal grows in plannar interface, 1< V 6 mm/min, in cellular morphology; V=8 - 12 mm/min, in primary dendrite; V > 15 mm/min, in developed delldrite. As V=12 mm/min, GL≈1000 and 400 K/cm, the crystal grows in cellular morphology developed dendrite, respectively. Crystals in cellular morphology are <110> preferred orientation and poor magnetostrictive property. Crystals in primary dendrite with <112> preferred orientation, have a good performance, the maximum value of magnetostriction (A) is 0.00175. Crystals in developed dendrite with part <112> orientation have an inferior property than the former.