Effects Of Alloying Elements Addition On Glass-forming Ability And Spin-glass Behavior Of Fe-based Amorphous Alloys

Fe-based amorphous alloys,with excellent soft magnetic properties,energy saving,environmental protection and other advantages,have been widely applied.However,except the soft magnetic properties at room temperature or high temperatue,Fe-based amorphous alloys have some special performance at low temperatures which are worth of research.Spin-glass materials have some non-equilibrium features,such as irreversible magnetization,relaxation effect and memory effect when the temperature is lower than a certain value,and they are promising candidates for magnetic storage materials at low temperature.So this thesis studied on the effects of alloying elements addition on glass-forming ability and spin-glass behavior of Fe-based amorphous alloys.In additon,X-ray diffraction(XRD)and differential scanning calorimetry(DSC)were used to detect the amorphous structure and the thermal stability.Also,physical property measurement system(PPMS)was used to measure the direct current(DC)and alternating current(AC)magnetization to analyze the spin-glass behavior of these alloys.Main researches are listed as follows:(1)Fe48-xCoxCr15Mo14C7B14Tm2(x=0,2,4,6,8,10)amorphous ribbons and rods by adding Co to Fe48Cr15Mo14C15B6Tm2 amorphous alloy were prepared.Effects of Co addition on the glass-forming ability and spin-glass behavior of these alloys were studied.It is found that stability of the amorphous phase and glass-forming ability is slightly improved with Co addition.The critical diameters of these alloys are iproved from 1.5mm to 2mm.The DC and AC magnetization chracteristics of all these amorphous ribbons coincide with spin-glass.Co content dependence of the peak value of magnetization Mmax?freezing temperature Tfs temperature at peak Tp and Curie temperature Tc increase at first then decrease as Co centent increased,which is similar to Slaer-Pauling curves.(2)Fe42Co6Cr15Mo14C7B14RE2(RE=Gd,Tb,Dy,Ho,Er,Tm)glassy ribbons and rods by changing the rare-earth elements of Fe42Co6Cr15Mo14C7B14RE2 glassy alloys were prepared.Effects of rare-earth elements on the glass-forming ability and spin-glass behavior of these alloys were studied.It is found that the critical diameter of RE=Er is less than 1mm while RE=Gd,Tb,Dy are 1.5mm and RE=Ho,Tm are 2mm.The DC magnetization chracteristics of amorphous ribbons of RE=Tb,Dy,Ho,Er,Tm coincide with spin-glass.However,the DC magnetization chracteristics of RE=Gd amorphous ribbons do not coincide with spin-glass.(3)Effects of C/B ratio on the glass-forming ability of Fe4sCr15Mo14CxB21-xTm2(x=3,5,7,9,11,13)were investigated.It is found that the supercooled liquid region ?T improved from 54K to 92K as C/B ratio increased.The critical diameters of these alloys are<1mm,<1mm,1.5mm,2mm,2.5mm and 8mm,thus the glass-forming ability has been significantly improved by increasing C/B ratio.The amorphous alloy system is paramagnetic at room temperature.(4)Fe42Co6Cr15Mo14C7B14Tm2 amorphous alloy with obvious spin-glass behavior and diameters up to 2mm was obtained.This makes it selective to manufacture magnetic storage devices applied at low temperature.