[en] The feasibility of preparing amorphous Ni₅₇Zr₂₀Ti₂₀Si₃ composite powders by mechanical alloying of pure Ni, Zr, Ti, Si, and ceramic powder mixture after 5 h milling was investigated. The as-milled powders were examined by X-ray diffraction, scanning electron microscopy, and differential thermal analysis. Amorphous Ni₅₇Zr₂₀Ti₂₀Si₃ composite powders were prepared successfully at the end of milling for all the compositions studied. The thermal stability of the amorphous matrix is not significantly affected by the presence of the ceramic particles. It is suggested a partial dissolution of the atoms constituting the ceramic species in the amorphous phase can result change of matrix composition and lead to the variation of the glass transition and crystallization behaviors

[en] Highlights: •15 at.% boron added to Al₈₇Y₈Ni₅ alloy demonstrates glass transition in contrast to its non-boron opponent. •A large 24.6 K ΔT_x (T_x−T_g) liquid supercooling range indicates (Al₈₇Y₈Ni₅)₈₅B₁₅ a possible ductile Al-based amorphous alloy. •Boron is effective in improving thermal stability of Al₈₇Y₈Ni₅ amorphous alloy by increasing the activation energy for crystallization by 43%. •The hardness in crystallization of the boron-containing alloy could achieve as high as 595 Hv. •Boron could affect the short-range and medium-range symmetry which delays the nucleation and crystallization kinetics. -- Abstract: In this study, 15 at.% of boron is added to increase the thermal stability and amorphous forming ability of Al₈₇Y₈Ni₅ alloy ribbons by single roller melt-spinning process. Thermal properties including crystallization activation energy and the Avrami exponent of crystallization are investigated using non-isothermal and isothermal analyses. Only the (Al₈₇Y₈Ni₅)₈₅B₁₅ amorphous alloy ribbon demonstrates a glass transition temperature (T_g) at 529 K, and its ΔT_x (=T_x − T_g) value is 24.6 K. Crystallization kinetic study show that the 15 at.% of boron increases the activation energy for crystallization from 159 to 228 kJ/mol. The Avrami exponent n value of Al₈₇Y₈Ni₅ amorphous alloy is 1.5 ∼ 2.1 indicating a decreasing nucleation rate with crystallization time, whereas the n value of (Al₈₇Y₈Ni₅)₈₅B₁₅ amorphous alloy ribbon is 2.3 ∼ 3.1 or the nucleation rate increases with time. The addition of boron could affect the crystal symmetry in atomic clusters and thus the phase separation behavior in the amorphous alloy. Boron is shown to delay the nucleation of boron-containing Al nano-crystals in crystallization. The maximum hardness is obtained for both non-boron and boron added alloys after crystallization at 592–596 K region due to formation of nano-crystallites. The highest hardness achieved is 575 and 595 Hv for Al₈₇Y₈Ni₅ and (Al₈₇Y₈Ni₅)₈₅B₁₅ alloys, respectively. Both the Al nano-crystals and solute-rich amorphous phase formed by phase separation contribute to the hardness increase