V.Yu. Zadorozhnyy

Mechanochemical synthesis and hydrogen sorption properties of nanocrystalline TiFe

The equiatomic intermetallic compound TiFe has been prepared by elemental mechanochemical synthesis in a planetary ball mill from Fe and Ti powders. The structural and phase transformations during synthesis were followed using X-ray diffraction. The reaction of the synthesized compound with hydrogen was studied volumetrically. The results demonstrate that the hydrogen capacity of the mechanochemical TiFe is 1.2 wt % at 2.5 MPa. Its absorption isotherm has an extended plateau in the range 1.6–1.7 MPa at room temperature.

Production of intermetallic compound of FeTi by means of mechanical-chemical synthesis and its interaction with hydrogen

A technique for producing the intermetallic compound FeTi by treatment of Ti-50 at % Fe powder mixtures in a high-energy ball planetary mill in argon atmosphere is demonstrated. The forming compound is in the nanocrystalline state with the size of coherent scattering areas (CSA) of 10–20 nm. A method of sample compaction from powder obtained by mechanical and chemical synthesis is proposed. It combines mechanical strength with initial phase composition and material microstructure. It is determined that, after high-temperature activation, the synthesized compound FeTi reversibly absorbs up to 0.6 wt % of hydrogen at room temperature.

Influence of cyclic loading on the onset of failure in a Zr-based bulk metallic glass

Samples of Zr62.5Cu22.5Fe5Al10 bulk metallic glass are subjected to uniaxial compression. Comparison of tests in monotonic loading and cyclic loading (repeated loading to the onset of plasticity, then unloading) shows that the compressive plasticity of the glass is drastically reduced under cyclic loading. It is argued that this effect arises from stress reversal accelerating the concentration of shear on a dominant shear band. The link with compression–compression fatigue results, and the consequences for low-cycle fatigue of metallic glasses are considered.

Ti–Ag–Pd alloy with good mechanical properties and high potential for biological applications

Ti-based alloys containing Ag were produced by tilt-casting method and their properties were studied. Even in its as-cast state, Ti94Ag3Pd3 showed relatively high tensile properties, good electrochemical behavior, and good biocompatibility. The relatively good mechanical properties of the as-cast α-Ti-type Ti94Ag3Pd3 alloy (tensile strength up to 850 MPa and elongation of ~10%) can be explained by its severely deformed, fine crystalline structure. The high biocompatibility of Ti94Ag3Pd3 can be explained by the Ag–Pd interaction, which inhibits the release of Ag ions from the surface. Ag, in combination with Pd has no toxic effects and demonstrates useful antimicrobial properties. The Ti94Ag3Pd3 alloy shows a good potential to be applied as a biomedical implant alloy.

Formation of Intermetallic Ni-Al Coatings by Mechanical Alloying with Different Intensities

Intermetallic Ni-Al coatings on the Ni substrate were prepared by the mechanical alloying (MA) method in mechanical activators of vibratory and planetary type. It was found that coatings that were fabricated in a high-energy (planetary) activator in comparison with those fabricated in a low-energy (vibratory) activator are more homogeneous, have higher density, and experience better adhesion to the substrate. It was shown that different intermetallic phases (NiAl, NiAl3, and Ni2Al3) can form directly during the MA treatment in the planetary activator.

Analysis of the Background Temperature During the Mechanical Alloying of Metal Powders in the Planetary Ball Mill

The background temperature of milling bodies and processed material is analyzed using calorimetric measures and methods of melting of reference substances during mechanical alloying of powders in planetary ball mill. It is shown that estimation of the background temperature using the calorimetric method provides more precise measurements compared to the melting method of reference substances. The dependence of background temperature change on mechanical alloying time, vial filling coefficient, mixture content of processed materials, rotation velocity of carrier, and processing atmosphere is presented.