Development of metallic glasses is hindered by the difficulties in manufacturing bulk parts. We report on the preparation of glassy alloys using the spark plasma sintering of gas atomized powders. The Zr57Cu20Al10Ni8Ti5 alloy processed has a high glass forming ability. Densification is obtained at the glass transition temperature (390 °C) under high pressure (≈500 MPa). Systematic study of the effect of powder particles size and sintering time is performed through structural and thermal analyses. Local and partial devitrification of the amorphous alloy is detected, resulting from local temperature overshoots. From these analyses, an approach of the spark plasma sintering mechanism of metallic glasses is proposed.

Bulk metallic glasses foams are under consideration as highly functional material, such as energy absorbers or ultra-lightweight parts, due to their porous structure combined with desirable strengths at relatively low densities. Also, the characteristics of high surface area of foams synthesized from metallic glasses make them viable candidates as emerging materials such as high-sensitivity sensors, catalysts or hydrogen storage media. In current study, bulk metallic glass foams were fabricated by extruding powder mixtures comprised of metallic glasses blended with various kinds of fugitive phases followed by dissolution of the fugitive phases in an aqueous chemical solution, for example HNO3, to yield the final porous structure. As a result of dissolution process, porous metallic glass having uniformly distributed micro-scale porosity was fabricated using a sequential synthesis technique beginning with composite particles comprised of composites of MG and a fugitive phase followed by consolidation of the composite powders via warm extrusion.

New glassy, crystalline and glass-crystalline materials from the GeSe2-Sb2Te3-CdTe system are synthesized by melt quenching technique. Using the results of the performed syntheses, X-ray diffraction analysis and scanning electron microscopy the glass forming region within this system is outlined. It lies partially on the GeSe2-Sb2Te3 and GeSe2-CdTe sides, as glassy samples are obtained up to 32.5 mol % Sb2Te3 and 27 mol % CdTe, respectively. Some assumptions about the structure of the samples are made on the basis of the results from the XRD investigations.

The glass-forming ability of chalcogenide glasses from the GeSe2-Sb2Te3-PbSb2Te4 system is investigated at different cooling rates. The samples are synthesized by direct synthesis in evacuated quartz ampoules from the initial compounds and quenched in air, water, water+ice+NaCl and liquid nitrogen with cooling rates of 3, 9, 34 and 400 K/s, respectively. The obtained bulks are characterized by visual and X-ray diffraction analyses. The critical cooling rate for obtaining chalcogenide glasses from the investigated system is 34 K/s. Above this rate the border between the glassy and crystalline phases shows a tendency towards narrowing of the glass-forming region.

The maximum value at equilibrium of the relaxed enthalpy of some glasses is viewed as alinear function of the annealing temperature from the Kauzmann temperatureTK up to a vitreous transition temperature T*g which is not time dependent. The frozen enthalpy and entropy at T*gare determined from the specific heat difference between glass andundercooled melt which is constant between TKandT*g. The Gibbs free energy change at T*g is equal to zero. The vitreous transition is a thermodynamic transitionwithout latent heat. A model is used to describe this phenomenon. A volume energy saving εv equivalent to a complementary Laplace pressure has beenadded to the classical Gibbs free energy change for a crystal formation in a melt. Thereis a change of the Vogel–Fulcher–Tammann (VFT) temperature at T*g corresponding to a decrease of the free volume disappearancetemperature. Scaling laws linking the crystal homogeneous nucleation temperatures to T*g are used to predict the two VFT temperatures, the thermodynamic vitreoustransition induced by vitreous (super)-clusters and the frozen enthalpy and entropy at T*g only knowing T*g, the melting temperature Tmand the fusion heat ΔHm of any fragileglass-forming melt.

X-ray absorption spectroscopy has been applied to probe the local structure of FeSc nanostructured amorphous solids around Sc atoms. At the Sc K-edge, the Fe90Sc10 nanoglass is characterized by a very short range order (EXAFS oscillations are only present up to k = 8 Å-1). A drastic difference in the phase and the amplitude of the nanoglass EXAFS signal compared to the amorphous ribbon indicating a different local structure around Sc atoms in both structures is observed. In addition, the changes in the local structure around Sc atoms are more significant than around Fe atoms.

The fragility of materials should be related to a local structure formed in supercooled liquid states. Especially, in the cases of metallic glasses, the icosahedral order formation is considered to play an important role. To clarify the relation between the local structure formation and the relaxation behavior (or fragility) in the supercooled liquid states of metallic glasses, molecular dynamics simulations were performed for a simple model of binary alloys, in which we can change the atomic size ratio. From the simulation results, we found that the icosahedral clusters exist in supercooled liquid states and form a medium-range network structure in strongly supercooled regime near the glass transition as well as in the glassy states. We also found that the number density of the clusters increases as the atomic size difference increases. Consequently, the calculated fragility parameter takes a lower value in a system with larger atomic size difference due to the richness of the icosahedral clusters.