| This paper mainly discusses the influence of heat treatment preservation time and thermal insulation temperature on the microstructure and magnetoelasticity of the quenching Fe-Ga. As-cast、purified and additional magnetic purified Fe83Ga17alloys have been quenched in water on the730℃and1000℃for1h、3h and5h respectively. The microstructure and mechanical properties of different state Fe83Ga17alloys have been observed. To obtain the best magnetoelasticity, the best heat-treatment process parameters are confirmed. Then the causes of these changes are analyzed. The results show that:1、As-cast、purified and additional magnetic purified Fe83Ga17alloys have been quenched to the room temperature in water on the730℃and1000℃for1h、3h and5h respectively, the grain have grown inordinately and become regular. The precipitates of rich Ga content reduce or even disappear. When extending the preservation time, the recovery and recrystallization are processed more fully. The grains in the room temperature are coarse. By rapid quenching, the high temperature organization are frozen to the room temperature. The precipitates of rich Ga content are controlled by rapid quenching. Addition to the X-ray diffraction patterns, alloys remain the same body centered cubic structure in both730℃and1000℃for different preservation time. But compared to the standard α-Fe, the diffraction angles of the peak position have shifted slightly. That is because the lattice are distorted by the addition of Ga. And the radius of Ga atom is larger than the Fe atom and they formed a type of solid solution. The lattice constant changes cause peak position shift. The peak are splitting in different degrees based on the X-ray diffraction pattern. This kind of splitting means the appearance of a new phase. After quenching heat treatment, the splitting of Fe-Ga alloys are weakened or even vanished gradually. So quenching can restrain the generation of this new phase.2、Compared to Ih and5h preservation time, as-cast Fe83Ga17alloys obtain the best magnetoelasticity under730℃、3h preservation time and quenched in water. Its saturation magnetostriction is95ppm which increased by82%on the base on the as-cast state. After1h and5h, the saturation magnetostriction are68ppm and81ppm respectively. Under the same heat treatment preservation temperature, the saturation magnetostriction are on the rise within1-3h. When extending to5h, the saturation magnetostriction decreases. The purified and additional magnetic purified Fe83Ga17alloys are the same. As-cast Fe83Ga17alloys just increase lOppm after1000℃、1h preservation and quenched to the room temperature which is not obvious. If extending to5h, its magnetoelasticity becomes worse. Under1000℃condition, the other two states follow the same regulation. Compared to the heat treatment with high temperature, the improvement of magnetoelasticity are more effectively near the Curie temperature Tc which is decided by different organization under different heat treatment.There are basic phase----disordered body centered cubic structure A2phase、short-range ordered DO3phase and other ordered phases when quenched near Tc. This organization are best for the magnetoelasticity of Fe83Ga17alloys. But when quenched from high temperature, the alloys maintains the disordered state in the high temperature and the magnetoelasticity decrease.3、When solidification under300mT magnetic field, quenched to room temperature in730℃for3h purified, the Fe83Ga17alloys presents the best magnetoelasticity. Under the same heat treatment condition, the increment of magnetostriction of purified Fe83Ga17alloys is89ppm and the magnetic purified is111ppm. When applied the external magnetic field on the solidification process, a part of magnetic domain are forced arranged on the perpendicular to the axial direction of the alloy bars. When applied an external magnetic field parallel to the axial, those magnetic domain which is90°with the external magnetic field make the biggest contribution to the magnetostriction. And this kind of magnetic domain is beneficial for magnetostriction. When Fe-Ga alloys are quenched under730℃and3h, partly disordered and partly ordered organization are formed. The external magnetic field during the solidification process and the heat treatment do not interplay. It is bring out the best in each other and improve the magnetoelasticity of Fe-Ga alloys sharply. |
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