Effect of similar element substitution on Fe-B-Si-Mo bulk metallic glasses studied by experiment and ab initio molecular dynamics simulation

Fe₇₂(B, Si, Mo)₂₈ bulk metallic glasses (BMGs) were successfully fabricated by conventional copper mold casting. The glass-forming ability of the Fe₇₂B₁₇Si₅Mo₆ BMG was enhanced by partial similar element substitution of Nb for Mo and Co for Fe, which was explained from the thermodynamic and atomic structural perspective. The thermal, magnetic and mechanical properties of Fe₇₂B₁₇Si₅Mo₆, Fe₇₂B₁₇Si₅(Mo_0.5Nb_0.5)₆ and (Fe_0.5Co_0.5)₇₂B₁₇Si₅(Mo_0.5Nb_0.5)₆ BMGs were investigated by experiment and ab initio molecular dynamics simulation. The Fe₇₂B₁₇Si₅Mo₆ BMG shows a high saturation magnetization (M_s) of 1.08 T, a low coercivity of 3.0 A m⁻¹, a high compressive yield strength of 4330 MPa and an outstanding plastic strain (ε_p) of 2.6%. Through similar element substitution, the M_s of (Fe_0.5Co_0.5)₇₂B₁₇Si₅(Mo_0.5Nb_0.5)₆ BMG decreases to 1.01 T owing to smaller magnetic moment of Nb and Co than Mo and Fe, and the ε_p increases to 3.5% because of less 15xx pair with five-fold symmetry.