Abstract: The design of high-entropy bulk metallic glasses (HE-BMGs) offers a promising strategy to achieve exceptional thermal stability and mechanical robustness of high-temperature structural materials. In this work, novel Fe₃₀Co₂₅Ni₁₅RM₅B_17.5Si_7.5 (RM = Nb, Mo, Ta, W) HE-BMGs with a unique combination of superior thermal stability, high-temperature strength, and wear resistance were developed. Among them, the Ta-bearing alloy (Ta5) exhibits the highest crystallization temperature, the widest supercooled liquid region, and the largest critical diameter for glass formation. The Ta5 HE-BMG demonstrates a sluggish crystallization behavior characterized by delayed nucleation and growth of the complex (Fe, Co, Ni)₂₁Ta₂B₆ primary phase. It also achieves ultrahigh specific strength even at 823 K and superior wear resistance, outperforming most reported HE-BMGs. Annealing at 833 K for 900 s retains its amorphous structure while further enhancing both the strength and wear resistance. Ab initio molecular dynamics simulations reveal that the Ta addition strengthens interatomic interactions, increases local five-fold atomic symmetry, and suppresses atomic diffusion, which rationalizes the experimental observations. With their exceptional combination of thermal and mechanical properties, the developed HE-BMGs, particularly the Ta5 alloy, emerge as promising candidates for high-temperature structural and wear-resistant applications.

Key words: High-entropy bulk metallic glass, Crystallization behavior, High-temperature strength, Wear resistance, Refractory metal alloying, First-principle calculation