Effect Of Alloy Elements On Glass-forming Ability And Thermal Stability Of Fe-based Amorphous Alloys

Fe-based amorphous alloys are a kind of novel amorphous materials with excellent soft magnetic performances and extensive prospect in applications. Fe-based amorphous ribbons and bulk metallic glasses were prepared by spin quenching and copper mold casting in this paper, respectively. Alloy elements, such as Ni, Zr and Nb, were added into Fe-based alloys with proper amount, and the effects on glass-forming ability (GFA) and thermal stability of Fe-based amorphous alloys were studied intensively by X-ray diffraction (XRD), differential scanning calorimeter (DSC) and scanning electron microscopy (SEM).The experimental results showed that the addition of Ni less than 4at% can improved GFA and enhanced thermal stability, however when the addition more than 4at% were added, GFA and thermal stability was depressed greatly with the accumulation and crystallization of clusters. Elements Zr and Nb with bigger atomic radius made this phenomenon much more distinctly. GFA of alloys was decreased when 1at% Zr were added, then the addition of Zr at 0.5at% and 2at% improved GFA greatly. 0.5at% Nb added in the alloy enhanced GFA by a large margin and the best GFA were gotten in this paper. The author thinks that sorts of closer packed clusters came into being with the additions and other elements, which were good for the enhancement of viscosity of mother alloys and bad for diffusion of atoms in long range during crystallization and GFA was improved.Compared to other three parameters, γ (γ=Tx/(Tg+Tl)) was a good one to measure GFA of Fe-based amorphous alloys in this paper. The experiments showed that the alloy with a higher γ was close to its eutectic component and had better GFA, and it can be prepared bulk metallic glass (BMG) easily. With a higher crystallization temperature Tx, lower glass transition temperature Tg and Liquidus temperature Tl, Fe-based amorphous alloys have better anti-crystallization performance and are more stable in liquid and glass states, which indicate that the alloy have a strong possibility of producing BMG.Isothermal annealed samples showed that no distinct crystal phases appeared when the temperature was 500℃, and α — Fe phase crystallized when annealed at 520℃, however when the sample annealed at 550℃, much more complex phases came out. The better thermal stability of samples the bigger crystalline grains precipitated. While diffused slim grains crystallized in ones which were not good at thermal stability. In our...