Rapidly solidified

The diethyl ester which is precipitated rapidly solidifies on stirring. Filter it at the pump, wash with water (2 portions each of about 20 ml.), and recrystallise from methylated spirit or from 95% ethanol. Yield of pale yellow crystals, 8-9 g. m.p. 135-I37 ... 

My ehosen examples inelude rapid solidifieation, where the extremity is in eooling rate nanostruetured materials, where the extremity is in respeet of extremely small grains surface seienee, where the extremity needed for the field to develop was ultrahigh vaeuum, and the development of vacuum quality is traced thin films of various kinds, where the extremity is in one minute dimension and quasierystals, where the extremity is in the form of symmetry. Various further examples could readily have been ehosen, but this chapter is to remain relatively short. 

The industrial technique now known as Rapid Solidifieation Proeessing (RSP) is unusual in that it owes its existenee largely to a researeh programme executed in one laboratory for purely scientifie reasons. The manifold industrial developments that followed were an unforeseen and weleome by-produet. 

Figure 10.7. Difi racUon paUern, prepared in an electron microscope, from a rapidly solidified foil of an A1 Mn alloy containing 14 at.% of manganese. Photograph made in 1984 (courtesy A.L. Greer...

In perhaps the most important technological observation, it was found that the reacted Ni3Al products have hardness values equivalent to cold-rolled or rapidly solidified NijAl containing boron additives. The hardness is notable in that the material contains a low density of dislocations. It is observed that crystallites are less than 10 nm in dimension. 

Schwartz, R. W. Payne, D. A. 1988. Crystallization behavior of chemically prepared and rapidly solidified PbTi03. In Better Ceramics Through Chemistry III, edited by Brinker, C. J. Clark, D. E. Ulrich, D. R. Mat. Res. Soc. Symp. Proc. 121 199-206. 

Gas Atomization 50-300 Standard deviation 1.9-2.5 <10-50 at high gas pressures with close-coupled atomizer Solder materials. Precious metals, Cu, Fe, Al, Mg, Co, Ti, Zn, Al-6Cr-3Fe-2Zr alloy. Low-alloy steels. High speed steels. Stainless steels, Specialty alloys, Ni-base superalloys, Alumina, Intermetallics io3-.o5 1-70 Spherical smooth particles. Cleanliness, Rapidly-solidified structures, Acceptable production rates High cost, Low 1 volume, Low energy efficiency (EE), Gas-filled porosity in particles H... 

This process, originally designated as RSR (rapid solidification rate), was developed by Pratt and Whitney Aircraft Group and first operated in the late 1975 for the production of rapidly solidified nickel-base superalloy powders.[185][186] The major objective of the process is to achieve extremely high cooling rates in the atomized droplets via convective cooling in helium gas jets (dynamic helium quenching effects). Over the past decade, this technique has also been applied to the production of specialty aluminum alloy, steel, copper alloy, beryllium alloy, molybdenum, titanium alloy and sili-cide powders. The reactive metals (molybdenum and titanium) and... 

Rapidly Solidified In-Situ Metal Matrix Composites 372... 

Rapidly solidified in-situ metal matrix composites. A design project for alloys based on the Fe-Cr-Mo-Ni-B system, and produced by rapid solidification, was undertaken by Pan (1992). During processing a mixture of borides is formed inside a ductile Fe-based matrix which makes the alloys extremely hard with high moduli. These alloys provide a good example of how phase-diagram calculations were able to provide predictions which firstly helped to identify unexpected boride formation (Saunders et al. 1992) and were ultimately used in the optimisation of the modulus of a shaft material for gas turbines (Pan 1992). 

In most Al-containing alloys, the shape of the particles was tear-drop like due to the tight surface oxide film. The typical shape was shown in Fig.l. The effect of rapid solidification on microstructures is shown in Fig. 5 for AI2CU (precursor for Raney Cu) with a small amount of Pd (11). In the case of slowly solidified (conventional) precursor, most of the added Pd was solidified as a secondary Pd rich phase shown by white dendritic structure in Fig.5 (a). On the other hand, no such secondary phase was observed in a rapidly solidified precursor as shown in Fig.5 (b). 

Figure 5. SEM views of slowly and rapidly solidified precursors of AI2CU+ 1.5%Pd...

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

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