《110》和《112》取向Tb-Dy-Fe超磁致伸缩合金的定向生长

采用区熔定向凝固方法,在30-720 mm/h生长速度范围内,均能获得〈110〉轴向择优取向生长的Tb-Dy-Fe合金;凝固形态随生长速度提高出现从平面晶到胞状晶、树枝晶转变;低速生长(30 mm/h)的样品磁致伸缩性能没有压力效应,高速生长(≥120 mm/h)的样品磁致伸缩性能具有明显的压力效应.低生长速度时〈110〉取向样品按双{111}系孪晶生长,高生长速度时按单{111}系孪晶生长,由此计算样品的磁致伸缩性能与实验结果基本吻合在更高生长速度下(900 mm/h)获得沿〈112〉轴向高度择优取向的样品,其磁致伸缩性能与高生长速度〈110〉取向样品性能相当,具有明显的压力效应.

110 AND 112 ORIENTED GROWTH OF Tb-Dy-Fe GIANT MAGNETOSTRICTIVE ALLOY

The directionally solidified Tb--Dy--Fe magnetostrictive alloys with <110> orientation were prepared in a velocity range from 30 to 720 mm/h, and the solidified morphologies change from planar, cellular to dendritic with increasing growth velocity. An obvious magnetostriction jump effect was observed in the sample with high growth velocity (>120 mm/h). Two kinds of twin growth mode, single--{111} and two--{111}--twin system were observed. The measured magnetostrictions of the samples are basically consistent with the calculated values by the above two twin growth mechanisms. As a comparison, the magnetostriction of <112> oriented crystals prepared with v=900 mm/h is corresponding to the <110> oriented crystals prepared with high growth velocities.