Tensile deformation behaviour of Zr-based glassy alloys

This paper presents a study of the deformation behaviour of a glassy phase in two Zr-based alloys, Zr₆₅Ni₁₀Cu₅Al_7.5Pd_12.5 and Zr₆₅Al_7.5Ni₁₀Pd_17.5, performed in situ in a transmission electron microscope. In contrast to the case of shear localisation and formation of 10–20 nm thick shear bands in deformed bulk glassy samples studied earlier, it is found that in thin (electron-transparent) samples the glassy phase in front of a crack deforms more homogeneously and no nanocrystallisation takes place. The reasons for such behaviour are discussed. According to the observed results, one can conclude that the studied metallic glasses can be intrinsically ductile in submicrometre-sized volumes.     

Glass formation in the Pd–Si-based alloys

Taking into account the importance of undercooling on glass formation, we propose a new criterion which allowed us to predict the best glass-forming composition, namely Pd₇₈Ag_5.5Si_16.5, among selected Pd–Si-based alloys ranging from binary to quaternary systems. The composition agrees well with that found experimentally. Using conventional copper mould casting, the Pd₇₈Ag_5.5Si_16.5 alloy is capable of forming fully amorphous rods with a diameter of 3 mm. The effects of Au and Ag additions on the glass-forming ability of the selected Pd–Si-based alloys have been investigated.     

Microwave-induced heating of a single glassy phase and a two-phase material consisting of a metallic glass and Fe powder

Metallic glasses exhibit low viscosity in a temperature range between the glass transition and the crystallization temperature, a feature that allows successful sintering of glassy powders. Microwave heating, being volumetric, has significant advantages over conventional heating in materials processing, such as substantial energy savings, high heating rates and process cleanliness. In the present study, we investigate the stability of Cu₅₀Zr₄₅Al₅ glassy powders and the formation of a bulk two-component metallic glassy-crystal sample by microwave heating in a single-mode cavity (915 MHz) in an alternating magnetic field.     

A structural model for surface-enhanced stabilization in some metallic glass formers

A structural model for surface-enhanced stabilization in some metallic glass formers is proposed. In this model, the alloy surface structure is represented by five-layer Kagomé-net-based lateral ordering. Such surface structure has intrinsic abilities to stabilize icosahedral-like short-range order in the bulk, acting as ‘a cloak of liquidity’. In particular, recent experimental observations of surface-induced lateral ordering and a very high glass forming ability of the liquid alloy Au₄₉Ag_5.5Pd_2.3Cu_26.9Si_16.3 can be united using this structural model. This model may be useful for the interpretation of surface structure of other liquid alloys with a high glass forming ability. In addition, it suggests the possibility of guiding the design of the surface coating of solid containers for the stabilization of undercooled liquids.