KULIK , T.

Bulk nanocrystalline Al88Mm5Ni5Fe2 alloys have been produced by consolidation of pulverised melt-spun ribbons at high pressure. Different production procedures were explored to improve the quality of compaction of the resulting bulk samples. Quality of compaction of samples pressed at room temperature is clearly improved by increasing applied...

The effect of substitution of Ce or Y by mischmetal (Mm) on the glass transition and the kinetics of crystallization of quaternary Al-Ni-Co-(Ce, Y, Mm) alloys was studied using isothermal and non-isothermal calorimetry and X-ray experiments. The alloy containing Mm shows more similarity to Ce containing alloy in all the studied properties than...

A direct extension of the Avrami equation considering the temperature dependence of the frequency factor is applied to describe the crystallization of a series of Al-Mm-Ni-Co amorphous alloys (Mm is a mischmetal). For high Al content, a nanocrystalline microstructure (fcc α-Al embedded in an amorphous matrix) is formed during the first...

X-ray diffraction patterns of mechanically alloyed Fe85Nb5B10 powder were fitted using whole powder pattern decomposition procedure to resemble the presence of α-Fe type crystals with different Nb content. To do so, a distribution of lattice parameters was proposed based on the asymmetry of the diffraction maxima and the broadening of the...

Specific heat at constant pressure, CP, was measured on amorphous and nanocrystalline Al88Y5Ni5Co2 alloys from differential scanning calorimetry experiments. Linear behavior of CP versus temperature from 323 to 423 K is explained by conduction electrons contribution and dilatation correction factor. Results indicate that the Fermi energy...

Hysteresis loops of nanocrystalline samples of Fe39Co39Nb6B16 - yCuy (y = 0, 1) HITPERM-type alloys were measured from room temperature up to 773K. The alloy with Cu shows a nearly constant value of coercivity (∼ 135A/m) in all the studied temperature range, whereas for the Cu-free alloy, the coercivity increases from 125A/m at 300K up to...

In this work, the relaxation of the amorphous structure of mechanically alloyed Fe70Zr30 powders has been analyzed through interrupted heating ramps below the devitrification temperature. As a result of such thermal treatment, Curie temperature and temperature at maximum magnetic entropy change curves shift to higher temperatures as the...

Temperature evolution of the coercivity of nanocrystalline samples of Fe60Co18Nb6B15Cu1 alloy with different crystalline fractions was measured from room temperature up to 690 K. Although room temperature coercivity increases as the nanocrystallization progresses, the thermal stability of the magnetic properties of the system is clearly...

Mechanical alloying process of Fe75Ge20Nb5 composition has been studied at different milling frequencies from initial pure powder mixture to the development of a single bcc phase (supersaturated solid solution). As an intermediate state, an intermetallic phase is formed, which disappears after further milling or after thermal treatment...

An almost single phase 14 M modulated martensite is obtained in melt spun ribbon of Ni55Fe17Ga26Co2 Heusler alloy. The effect of thermal treatments on the stability of the reverse martensitic transformation from 14 M modulated martensite to austenite phase in this system has been investigated by both non-isothermal and isothermal treatments....

Dynamics of a single ball into a planetary ball mill is analyzed leading to a cubic dependence of the power transferred during milling with the rotational speed, Ω. This leads to the definition of an equivalent time to describe the state of ball milled powders independently of Ω. Mechanical alloying of Fe75Ge20Nb5 composition is studied by a...

The influence of the fabrication method on the magnetostructural properties of a Ni55Fe19Ga26 Heusler alloy, obtained both as a ribbon, by melt-spinning, and as a pellet, by arc-melting, has been analyzed. It has been found that, while the arc-melting technique leads to the precipitation of the gamma phase and to a non-modulated...

Intermetallic phases in the Fe-Nb system have been obtained as products of the devitrification of a homogeneous amorphous Fe70Nb30 alloy prepared by mechanical alloying. Besides Fe2Nb Laves and Fe7Nb6 intermetallic phases, α-Fe phase has been detected by X-ray diffraction (XRD). Hyperfine parameters for both Fe2Nb and Fe7Nb6 intermetallics have...

Ribbons of a Ni55Fe19Ga26 Heusler alloy were prepared by melt spinning technique. The effect of pressure on magnetostructural transitions was studied comparing as-spun ribbons to ribbons previously submitted to an axial pressure and to powder obtained from manually grinded as-spun ribbons. The martensitic transformation present in the as-spun...