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Abstract: A combination of two criteria, which have been recently reported in the literature to predict compositions with high glass-forming ability, has been applied in the present work for the Ni–Ti system. The first criterion is an extension of the topological instability ‘λ criterion’, used here to indicate (and avoid) the composition fields associated with the crystallization of the first phase (solid solution or intermetallic compound) to appear during crystallization. The second, the thermodynamic criterion, is based on the calculation of a parameter (γ∗) that relates the enthalpies of all the competing phases including the amorphous one. A combination of these two criteria for the binary Ni–Ti system indicated the existence of only a narrow composition interval for glass formation. Alloy compositions in this interval were prepared by melt-spinning and the glass-forming ability (GFA) of the as-cast ribbons was evaluated by X-ray diffraction and differential scanning calorimetry. The results indicated that the two criteria are complementary, since compositions with high GFA are expected to have a high γ∗ parameter and also correspond to intervals where the λ parameter is greater than 0.1. [Copyright &y& Elsevier]

In the present work the fluxing technique was applied to the Sn–51 wt.% Se hypoeutectic alloy. The aim was to study the influence of the undercooling on the microstructure of this alloy, particularly concerning the formation of oriented microstructure and even some metastability occurrence. High undercooling (63 °C) was achieved for the primary SnSe phase leading to an oriented microstructure in the firstly solidified region. Although the undercooling for the eutectic was not so high (19 °C) morphological changes were observed. The rapid movement of the interface interfered with cooperative eutectic growth producing an irregular eutectic in the first region to solidify followed by a fine lamellar and directional eutectic. In order to detect some supersaturated solid solution in the SnSe phase a precise lattice parameter measurement was done from the accurate performed X-ray diffraction (XRD) on the firstly solidified region of the sample. [Copyright &y& Elsevier]

Using the intrinsic materials properties of bulk metallic glasses (BMGs), namely electrical resistivities two orders of magnitude higher than good conductors and a Newtonian viscous-flow regime of deformability, a new electromechanical process has been developed for shaping, joining and engraving of BMGs. Viscous flow in the supercooled liquid region between the glass transition temperature Tg and the crystallisation temperature Tx of the bulk metallic glass allows rapid electromechanical shaping, joining and engraving at low applied stresses. The process parameters are adaptable for the full maintenance of the glassy state. Miniaturisation of the process is expected to allow sub-millimetre range manipulation and submicron-engraving. [Copyright &y& Elsevier]

A new type of amorphous and nanocrystalline alloys has recently been produced and called HITPERM. These alloys are FeCo-based and their soft magnetic properties persist to α–γ phase transformation at 980 °C. Their soft magnetic properties are attributed to α′-FeCo phase formation during the crystallization process. The FeCo-based alloys present superior magnetic flux density and permeability when compared to FeSi-based and FeZr-based alloys. Because these alloys are potentially applicable in components working at high temperatures, their oxidation behavior and magnetic properties require careful analysis. This work presents a magnetic property and oxidation resistance comparison of two different FeCo-based alloys: Fe38.5Co38.5Nb7Cu1B15 and Fe38.5Co38.5Zr7Cu1B15. The results showed that the Nb addition instead of Zr addition improve the corrosion and oxidation resistance of FeCoZrCuB alloys. The decrease of saturation magnetization due to the corrosion processes was higher to the Fe38.5Co38.5Zr7Cu1B15 alloy than to the Fe38.5Co38.5Zr7Cu1B15 alloy. [Copyright &y& Elsevier]

A new type of amorphous and nanocrystalline alloys has recently been produced and called HITPERM. These alloys are FeCo-based and their soft magnetic properties persist to α–γ phase transformation at 980 °C. Their soft magnetic properties are attributed to α′-FeCo phase formation during the crystallization process. The FeCo-based alloys (HITPERM) present superior magnetic flux density and permeability when compared to Fe-based alloys (FINEMET and NANOPERM). Because these alloys are potentially applicable in components working at high temperatures, their oxidation behavior and magnetic properties require careful analysis. This work present a magnetic property and oxidation resistance comparison of one traditional FeCo-based alloy and one traditional Fe-based alloy: Fe38.5Co38.5Nb7Cu1B15 (HITPERM) and Fe73Nb3Si13.5B9.5Cu1 (FINEMET); other with Si addition: Fe36Co36Nb6Cu1Si10B11; other with Cu suppression: Fe36Co36Nb7Si10B11 and a new one composition with highly magnetic and oxidation resistance: Fe33.5Co33.5Nb7Si15B11. [Copyright &y& Elsevier]

Abstract: A combination of an extension of the topological instability “λ criterion” and a thermodynamic criterion were applied to the Al–La system, indicating the best range of compositions for glass formation. Alloy compositions in this range were prepared by melt-spinning and casting in an arc-melting furnace with a wedge-section copper mold. The GFA of these samples was evaluated by X-ray diffraction, differential scanning calorimetry and scanning electron microscopy. The results indicated that the γ * parameter of compositions with high GFA is higher, corresponding to a range in which the λ parameter is greater than 0.1, which are compositions far from Al solid solution. A new alloy was identified with the best GFA reported so far for this system, showing a maximum thickness of 286μm in a wedge-section copper mold. [Copyright &y& Elsevier]