Narrow Results

We have produced bulk amorphous materials by quenching arc melted melts in water cooled copper die. Alloys of the composition Zr₅₇Cu₂₀Al₁₀Ni₈Ti₅ and Zr₅₅Cu₁₉Al₈Ni₈Ti₅Si₅ were produced in the form of small cylinders with a diameter of 3 mm and a length of 25 mm. The alloys were investigated by X-ray diffraction and thermal analysis to determine the structure and thermal properties. Complete amorphous X-ray patterns were observed for both alloys. The glass transition temperature is 362°C for the Zr₅₇Cu₂₀Al₁₀Ni₈Ti₅ alloy and 363°C for the Zr₅₅Cu₁₉Al₈Ni₈Ti₅Si₅ alloy. The crystallization temperature of the Zr₅₇Cu₂₀Al₁₀Ni₈Ti₅ alloy was measured to be 414.6°C. The Zr₅₅Cu₁₉Al₈Ni₈Ti₅Si₅ alloy has a higher crystallization temperature of 425.5°C.

The amorphous alloys of Co₅₀Fe₂₀Cu₂V₈B₂₀ are successfully obtained by using the mechanical alloying technique. The sample is analyzed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The DSC result of the powder sample milled for 120 h shows a complete amorphous phase and a wide supercooled liquid region (T_x - T_g ≃ 80 K).

Mechanical alloying by high energy ball milling is a promising method for the production of bulk metallic glasses, amorphous alloys and nanostructured materials. Amorphous alloys reinforced by nanocrystals represent a big step in the optimization of new ultra high strength materials. Nano-scale W-Y solid solutions were synthesized by high energy ball milling. Only 1 at. % oxygen can stabilize the bulk metallic glassy state of Zr₅₄Cu₁₉Ni₈Al₈Si₅Ti₅O₁ to higher T_x and to large supercooled liquid range ΔT_xg.

Fe-based amorphous alloys are important materials with a high potential for commercialization by evaluating their corrosion performances. In this work, amorphous Fe${}_{73.5}$Cu₁Nb₃Si${}_{13.5}$B₉ alloy was chosen as a target material to investigate the effects of the addition of C on the corrosion properties by an electrochemical method. Alloy ingots Fe${}_{73.5}$Cu₁Nb₃Si${}_{13.5}$C${}_x$B${}_{9-x}$ (x = 0, 1, 2, 3 at.%) were prepared using an arc melting system, under argon atmosphere. Planar flow melt spinning of the alloys was carried out to obtain amorphous ribbons of the width $\sim$5 mm and the thickness about 30 $\mu$m. Effects of the addition of C into Fe${}_{73.5}$Cu₁Nb₃Si${}_{13.5}$B₉ amorphous soft magnetic alloys were investigated in acidic solutions. Studies of potentiodynamic polarization and electrochemical impedance revealed the passivation ability and corrosion resistance of the amorphous ribbons with C in the 0.1M H₂SO₄ media at room-temperature. The amorphous ribbons showed excellent corrosion resistance with formation of a stable passive film. It can be obviously observed that the addition of C significantly improves the corrosion resistance.

Metallic glasses (amorphous alloys) consist of atomic clusters, interconnecting zones and free volume. The atomic clusters are connected together, resulting in the formation of a rigid skeleton through the interconnecting zones. Some metallic glasses even contain crystalline structures at the nanoscale. Even though there is supposed to be no structural change at temperatures below the glass transition temperature, metallic glasses exhibit different mechanical behaviors at cryogenic temperatures. Contrary to crystalline materials, the strength and ductility of some metallic glasses and their composites both show a significant increase with decreasing temperature in the cryogenic temperature range. This paper briefly reviews these phenomena.

In this paper we investigated the structure of amorphous and nanocrystalline alloys of CoNiW obtained by electrolytic deposition. Studies were performed by transmission electron microscopy in HAADF mode and atomic force microscopy. In the course of the work was to obtain new data on the structure of materials. It has been found that tungsten is more homogeneous distributed in the alloy than nickel or cobalt. This is due to higher mobility of the atoms of nickel and cobalt in the electrolyte.