Studies On The Preparation And Magnetocaloric Effects Of Mn_60-xFe_xAl₄₀Fe And Fe_91-xLa_xZr₉Amorphous Alloys

This thesis mainly reported the preparation and magnetocaloric effectsof the Fe_91-xLa_xZr₉（x=1,3,5,10） and Mn_60-xFe_xAl₄₀（x=21,23,25,27,29） amorphous alloys. The amorphous alloys were prepared by using arcmelting and melt spinning methods. X-ray diffraction （XRD） are used forphase composition analysis and the vibrating-sample magnetometer are usedfor magnetic properties and magnetocaloric effects.We investigated the preparation of amorphous Fe_91-xLa_xZr₉（x=1,3,5,10） alloys and their magnetic and magnetocaloric properties. The samples ofthe amorphous alloys were prepared by using arc melting and melt spinningmethods. X-ray diffraction shows that the samples form in amorphous state.The isothermal magnetic entropy change of Fe81La10Zr9alloy wasdetermined from magnetization data basis on Maxwell relation. The resultshows that the maximal magnetic entropy change is0.8J/kg·K. Thehalf-peak wide temperature span is from245K to285K.The Mn_60-xFe_xAl₄₀（x=21,23,25,27,29） alloys have been prepared atthe speed of30m/s and40m/s, respectively. The X-ray diffraction resultsshow that all the compounds crystallized in eutectic alloy phase, that is themixture of crystalloid and some amorphous phase. From the magneticmeasurements, the Curie temperature of the two series alloys decrease withincreasing of x. That is, when prepared at the speed of30m/s, the Curietemperature gradually decreased from355K as x=21to185K as x=29,but gradually decreased from329K as x=21to209K as x=29whenprepared at the speed of40m/s. From the differential of the isothermalmagnetization curves, it can be easily observed that the maximal magneticentropy-change are0.73J/kgK and0.63J/kgK when the speed is30m/s and40m/s.