The Research Of Fe-Ga-Al-Tb(Dy)Magnetostrictive Materials

Tb-Dy-Fe magnetostrictive materials are widely used in recent years, but because of its poor mechanical performance and large saturation magnetization field, the research of it has dropped. Fe-Ga is becoming the research focus due to good magnetostrictive and mechanical properties. Fe-Ga-Al alloy has the best performance in the alloys. Adding Tb and Dy into Fe-Ga-Al alloy would increase the magnetostrictive properties. The paper makes a system research on the Fe-Ga-Al-Tb and Fe-Ga-Al-Dy alloy.The paper mainly studies the phase structure and magnetic properties of the Fe81Ga17Al2alloy after adding Tb and Dy elements, and the effects on the phase structure and magnetic properties after heat treatments.The main experimental methods include:metallurgical microscope, scanning electron microscopy and energy spectrum analysis (SEM-EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and differential scanning calorimetry (DSC) and so on. The following are experimental procedures and conclusions:Tb is added into Fe81Ga17Al2with0.1at.%,0.15at.%,0.2at.%,0.25at.%,0.3at.%and0.5at.%, The alloys are melted in the vacuum arc furnace. The results show that:The phase structure is the disordered bcc a-Fe structure, the lattice parerment is declining with the increase of Tb. Alloy microstructure is dendritic morphology, and the distribution of Tb element in the alloy was uneven, higher content in the grain boundaries and the low content in the grain size of the internal. Tb makes the Fe-Ga alloys preferred in [100] orientation, and improves the magnetostrictive coefficient, keeping the alloys a good performents of soft magnetic. Magnetostrictive coefficient of Fe81Ga17Al2Tb0.2achieved261ppm.Fe81Ga17Al2-0.2at.%Tb alloy are heated with700℃,770℃,840℃, and910℃for three hours and then quenched. Magnetostriction strain increases at first and then decreases along with the heat treatment temperature rising, and the value of770℃-quenched alloy is the largest, up to220ppm. Compared with the casting one, the Xs of alloy is declining, the main reason we guess is that the disordered D03structure becomes ordered during the heat process which maked a bad effect on the magnetostriction.The effect of Dy on the performance of pheas structure and magnetostrictive properties of (Fe81Ga17Al2)1-xDyx (x=0.1,0.2,0.3,0.4,0.5) alloys were studied. The results show that:The phase structure is the disordered bcc α-Fe structure, and the lattice parement is declining with the increase of Dy. Dy was found in grain boundary, and also appeares as punctate separation phase in matrix. Alloy microstructure is consisted with the ordinary hexagon grain and mesh shape grain. Dy makes the alloys preferred in [100] orientation, and improved the magnetostrictive coefficient. The saturation magnetostrictive coefficient of0.5at.%Dy alloy achieved to332ppm, it has exceeded the λs of rare earth research institute of Baotou.