Amorphous Formation, Magnetic Properties And Magnetocaloric Effect In LaFe_11.5Si_1.5B_x And La₁₀Fe_81-xZr₉B_x

The LaFe11.5Si1.5Bx (x=0.1,0.2,0.3,0.4,0.5), La10Fe81-xZr9Bx (x= 0,1, 2,3,5,6,7,8,9,10 15) Preparation of Amorphous and magnetic properties were systematically investigated in this work. By arc melting technology to La, Fe, Si, Zr, Fe4B were melting into LaFe11.5Si1.5Bx (x= 0.1,0.2,0.3,0.4, 0.5), La10Fe81-xZr9Bx (x= 0,1,2,3,5,6,7,8,9,10,15) series of master alloy, and then prepared by single roller melt-spinning into the strip samples. Using X-ray diffraction (XRD) for phase and crystal structure analysis; using vibrating sample magnetometer (VSM) by means of, respectively, of the strip alloy magnetic properties and magnetocaloric effect; Individual samples were Differential Scanning Calorimetry (DSC) of the material glass transition temperature of the initial crystallization temperature. The results show that:(1)On LaFe11.5Si,.5Bx (x= 0.1,0.2,0.3,0.4,0.5) alloy system, using a single roller melt-spinning ribbons prepared samples by XRD analysis showed that for the eutectic alloy system, there is precipitation, there are still some Amorphous phase. Magnetic measurements and XRD results show the consistency of thin alloy quenched high with the second phase shows ferromagnetism. According to the thermodynamic Maxwell relation, the isothermal magnetization data from the series of compounds to determine the magnetic entropy change, the results show that the alloys of the magnetocaloric effect small, but larger cooling temperature.(2)Rejection with different speed (roller surface speed 40 m/s,50 m/s) was prepared La10Fe81-xZr9Bx (x= 0,1,2,3,5,6,7,8,9,10,15.) As the B content increased gradually increase the melting point alloy, amorphous ribbons prepared by gradually increasing the difficulty. XRD shows x<3 when the fast quenched ribbons are amorphous. Magnetic measurements show Curie temperature of amorphous alloy changes occur repeatedly. Isothermal magnetization (M-T) curve shows the alloys experienced two phase transitions.Changes in the external magnetic field when the 0-1.5 T, x= 0 sample the isothermal magnetic entropy change 0.83 Jkg-1 K-1, this value is in the same field of metallic Gd 1/4;x= 2 the magnetic entropy change of about 0.42 Jkg-1K-1...