【摘要】 采用熔融玻璃净化与循环过热相结合的方法制备过冷度分别为198、270、300K的Fe81Ga19合金,对不同过冷度的Fe81Ga19合金进行定向激发以获得具有轴向择优取向的棒材,并研究其显微组织和择优取向.结果发现:过冷度为198K的合金其凝固组织为细小的粒状晶或准球状晶,过冷度为270K的合金,晶粒尺寸增大,发生多边化转变,形态上表现为等轴晶,晶粒内部存在大量亚晶界;过冷度增加至300K的合金经定向激发后晶粒进一步粗化,晶粒呈一定的取向沿轴向方向排列.X射线衍射分析表明,深过冷Fe81Ga19合金经过定向激发后其凝固组织具有明显的〈110〉择优取向,其中过冷度为270K的合金定向激发后出现有利于磁致伸缩性能的〈100〉取向,并且衍射峰出现劈裂现象,DSC曲线在820℃左右出现一明显的吸热峰,对应于A2+修正DO3→A2的相转变,证明快速凝固的深过冷定向激发Fe81Ga19合金棒材中存在四方结构畸变的新的DO3相结构.更多还原

【Abstract】 By using glass fluxing purification combined with superheating cycling method,the alloys Fe81Ga19 with undercooling to 198,270 and 300 K were prepared and activated directionally to get a axial-orientation preferred bar.The microstructure and preferred orientation of alloys Fe81Ga19 with different undercooling were then studied with optical microscope and X-Ray diffraction analysis.The result showed that the solidification structure alloy Fe81Ga19 with undercooling of 198 K was of tiny granular crystal or quasi-ball crystal.For undercooling of 270 K,the grain size increased and changed into equiaxial crystal,after the multiple edge transformation took place,and there were more sub grain boundaries in the grain.When the undercooling increased to 300 K,the grain became more bulky and distributed with certain orientation along the axis.X-ray diffraction analysis showed that the solidification structure of super-cryogenic alloy Fe81Ga19 after directional activation exhibited obvious 〈110〉 preferred orientation.The alloy with the undercooling of 270 K exhibited 〈100〉 orientation beneficial to the magnetostriction,and the diffraction peak split took place.In DSC curve,a clear heat absorption peak appeared at about 820 ℃,corresponding to the A2 +modified DO3→A2 phase shift,verifying that there was existing of the new distorted DO3 phase with quadratic structure in rapid directionally solidified undercooled alloy Fe81Ga19.更多还原