The Structure And The Mechanical Properties Of Rapidly Quenching Iron And Tungsten Based Alloys

In this paper, a series of Fe- and W-based alloys were prepared by using arc melting furnace and copper mold casting method under an argon atmosphere. The microstructure and phases constituent were investigated by employing scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. The thermodynamic characteristic for amorphous samples and mechanical properties for as-cast samples were investigated by means of differential scanning calorimeter (DSC) and electronic universal tester. In addition, Ribbons for W-based alloys were fabricated by single roller melt spun method in order to check to glass-forming ability (GFA) of interested alloys.The results show that the GFA for Fe_61.5-xCo₃Mo₁₄C₁₅B₆Er_0.5M_x(x=2, 3 and M=Ni, Nb, respectively) alloys characterized by amorphous sample size is 1.5-3mm in diameter. The largest supercooled liquid region up to 76K and highest fracture strength up to 3890MPa and certain plastic strain of 0.93% were found for Fe_58.5Co₃Mo₁₄C₁₅B₆Er_0.5Ni₃ bulk metallic glass. The soft the magnetic properties of Fe_61.5-xCo₃Mo₁₄C₁₅B₆Er_0.5Ni_x (x=2, 3) alloys characterized by saturated magnetization (M_s) and coercivity (H_c) are 0.8T and 3.46A/m, respectively, for x=2 alloy and 1.2T and 2.83A/m, respectively, for x=3 alloy.The microstructure and mechanical properties of W₂₁Fe_70.89-xNi_xB_8.11(x=0, 20, 40, 45, 64) alloys were studied in this experiment. FeWB phase in the structure is decreased when the content of Ni is increasing, and the precipitated phase W2B5 from FeWB was observed with the disappearance of Fe₂ W phase and the appearance of (Fe,Ni) solid solution. Which results in the yield strengths decrease from 1930MPa to 1622MPa and the plastic strains increase from 4.5% to 17.5%. While the minimum facture strength over 1800MPa is only found for x=20 alloy.The glass-forming ability for W₃₅Fe₃₀C₁₇B₁₈,W₃₅Fe₃₀C₁₅B₂₀ and W₃₀Fe₃₀C₁₁B₂₄ alloys were investigated by single roller melt spun method. XRD analysis results show that the single amorphous phase was only obtained for W₃₅Fe₃₀C₁₅B₂₀ alloy, which shows the largest GFA, when C+B=35at% was maintained. The GFA, However, was not improved when adjusted iron and boron elements without changing carbon element for W₃₅Fe₃₀C₁₅B₂₀ alloy. The silicon element was used and W₃₅Fe₃₀Si₁₅B₂₀ and W₃₅Fe₂₅C₁₀B₂₅Si₅ were designed. Full amorphous phase ribbons for those alloys can not observed, which shows that the GFA for W-based alloys is very sensitive to alloy composition.