取向柱晶组织Fe-Ga合金轧制板带的织构遗传与控制研究

The study of textured Fe-Ga alloy sheets is not only the inquiry for development of high technology such as ultrasonic transducer, micro displacement control, and waveguide detection, but also is one of research emphasis for magnetostrictive materials. However, compared with single crystals and textured polycrystals, magnetostrictive properties of the Fe-Ga rolled sheets is low, which is due to not yet obtained {100}<001> orientation in the rolled sheets, because <001> direction of Fe-Ga alloy has maximum magnetostriction coefficient. Based on preliminary work, Fe-Ga alloy with <001> orientation and coarse columnar grain structure is obtained by directional solidification technology. Based on the theory of solidification and forming, and according to the structure heredity characteristics and control method during of preparation and forming process, the evolution and hereditary of texture during rolling deformation and recrystallization process in <001> initial orientation Fe-Ga alloy with columnar grain will be investigated, which is useful to find out the control method of {100}<001> cubic texture. We hope our research results will find out the difference of texture evolution and hereditary between columnar grain and equiaxed grain, and provides theoretical basis for texture control in Fe-Ga alloy sheets.

研究强织构、大磁致伸缩Fe-Ga合金板带材料，不仅是超声换能、微位移控制、超声导波检测等高技术领域发展的需要，同时也是磁致伸缩材料研究的重点之一。然而，与单晶、取向多晶块体材料相比，轧制Fe-Ga板带的磁致伸缩性能还较低，这与板带不能获得高取向度{100}<001>立方织构密切相关(<001>方向具有最大磁致伸缩系数)。本项目是在前期工作的基础上，采用定向凝固技术赋予Fe-Ga合金<001>取向和粗大柱状晶组织，依据控制凝固与控制成形的基础理论，结合制备与成形加工全过程的组织遗传特征及其控制方法，研究具有初始柱状晶组织及<001>取向的Fe-Ga合金在热、冷变形及再结晶过程中织构的演变规律及遗传性，寻找立方织构的控制理论及方法，在理论上弄清楚柱状晶在变形及再结晶过程中的演变规律、织构遗传性及与等轴晶的差异，在应用上为轧制Fe-Ga合金板带中立方织构的织构控制提供理论依据和技术基础。

与单晶、定向凝固取向多晶块体材料相比，轧制Fe-Ga板带材料的磁致伸缩性能还较低，这与板带不能获得高取向度{100}<001>立方织构密切相关。本项目采用定向凝固技术赋予Fe-Ga(Al)合金<001>取向和粗大柱状晶组织，研究了具有初始柱状晶组织Fe-Ga(Al)合金在热、冷变形及再结晶过程中织构的演变规律及遗传性，厘清了柱状晶在变形及再结晶过程中的演变规律、织构遗传性及与等轴晶的差异。项目得出以下重要结论：①二元Fe-Ga合金板带获得较强的高斯织构，归因于初始<100>取向柱状晶的遗传性。原始<100>取向柱状晶轧后变为{111}<112>织构，但内部有高斯取向的切变带，再结晶时是优先形核地点；取向柱状晶粒轧后残留下少量高斯取向的显微带，也是再结晶的优先形核地点。②三元Fe-Ga-Al合金具有较好的塑性，采用温轧+冷轧的轧制工艺制备Fe-Ga-Al合金薄板，与传统工艺（热轧+温轧+中间退火+冷轧）相比，温轧+冷轧制备的合金薄板变形储能大，初次再结晶{111}晶粒（含<111>∥RD织构的晶粒）含量显著增多，在高温热处理时{110}晶粒在长大过程中可吞并较多{111}晶粒，<001>∥RD织构分数达到80.5％，所得样品的饱和磁致伸缩系数较高。③合金薄板的<001>方向具有最大的饱和磁致伸缩系数，偏离<001>方向饱和磁致伸缩系数显著下降，其中<111>方向的饱和磁致伸缩系数最低，约-7 ppm，<110>方向的饱和磁致伸缩系数约58 ppm。本工作探索出利用初始取向柱晶的织构遗传性制备<100>取向Fe-Ga(Al)合金轧制板带的新原理新方法。本工作所研发的强织构、高性能Fe-Ga磁致伸缩轧制带材，在换能、致动以及传感等技术领域有重要应用前景。