Amorphous rapid solidification

Using rapid solidification technology molten metal is quench cast at a cooling rate up to 10 °C/s as a continuous ribbon. This ribbon is subsequently pulverized to an amorphous powder. RST powders include aluminum alloys, nickel-based superalloys, and nanoscale powders. RST conditions can also exist in powder atomization. 

The equilibrium, room temperature structure of pure cobalt is hep. The fee structure is stable at high temperatures (422 °C to 1495 °C) and has been retained at room temperature by rapid solidification techniques [101], X-ray diffraction analysis was used to probe the microstructure of bulk Co-Al alloy deposits containing up to 25 a/o Al and prepared from solutions of Co(II) in the 60.0 m/o AlCfi-EtMelmCl melt. Pure Co deposits had the hep structure no fee Co was observed in any of the deposits. The addition of aluminum to the deposit caused a decrease in the deposit grain size and an increase in the hep lattice volume. A further increase in the aluminum content resulted in amorphization of the deposit [44], Because the equilibrium... 

While interest in amorphous alloys was becoming vane over the time, the paradigm shift in materials science brought about by the discovery of amorphous metals and rapid solidification cannot be underestimated. The interest of physicists, chemists, materials scientists, and engineers became refocused from well-ordered crystalline materials to disordered and nanocrystalline phases. Shortly, substantial R D programs were initiated in the USA, Japan, and worldwide both at universities and national government laboratories. Foundations have been established for the advance of the science of nanomaterials. 

Rapid solidification and devitrification of amorphous metals and metallic glasses Combustion-flame chemical vapor condensation processes (Kear) Induction-heating chemical vapor condensation processes DC and RF magnetron sputtering, inclusive of the method of thermalization Laser ablation methods Supercritical fluid processing... 

The alloys are first produced by rapid solidification and are amorphous in nature. They are either directly fabricated as powders, by a process such as high-pressure gas atomisation (HPGA), or by melt-spinning of ribbons, which are subsequently pulverised to form a powder (<150 /im). The powders are then consolidated by hot extrusion between 950-1050°C where the initial amorphous structure breaks down and forms a fine dispersion of stable borides in a ductile Fe-based matrix. 

Although rapid solidification may not produce a truly amorphous (noncrystalline) material for some alloy compositions, crystallite sizes of rapidly solidified crystalline... 

Rapid solidification and devitrification of amorphous metals and metallic glasses... 

Amorphous alloys Rapid solidification (amorphization) Exchange interaction Composition... 

Apart from its technical performance the material is based on the inexpensive raw materials iron and silicon. The amorphous precursor material for the Fe-Si-B-Nb-Cu alloys, furthermore, is easily accessible by rapid solidification from the melt - a well established technique for large scale production of amorphous metals. 

Rapid solidification 10 -10 Pulsed laser melting of a solid surface Amorphous and nanocrystaUine thin films... 

Rapid solidification processing (RSP), for example, by melt spinning onto a cooled copper drum, which is capable of retaining many alloys in a glassy (amorphous) state or in nanocrystalline form ... 

Amorphous films of PVF2/PMMA blends were prepared by initial precipitation from a solvent and rapid solidification at 15 °C from the molten state (Martfnez-Salazar et al., 1991). Moreover, these two constituents were considered as miscible (Noland et al., 1971). The PVF2/PMMA compositions studied were 25/75,45/55, 50/50, 55/45, 60/40 and 75/25 by weight. The presence of a single X-ray halo as well as a single Tg value for all the blends, in the above compositions range, favours the view that these materials are composed of homogeneous mixtures at molecular level. The parallel decrease of the microhardness, which obeys a simple expression ... 

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