Submicron-sized microstructure

The ability to scale up the abc deformation approach to form SMC structure in a large-scale Ti-64 billets was demonstrated via prototype production. The billets (150 mm in diameter and 200 mm in length) solution treated at 1010°C for 0.5 hr followed water cooling were subjected to near-isothermal multi-step forging comprising of specific combination of multiple upset/drawing operations [3] at the thermo-mechanical conditions provided formation of submicron-sized microstructure. 

Likewise, 99% dense samples with a submicron-sized microstructure have been obtained by Tokita, by the consolidation of a submicron starting powder without... 

In order to discuss the effect of Al-B-C addition to SiC on p-a phase transformation of SiC and microstructure of porous SiC ceramics, porous SiC ceramics without AI-B-C additives were fabricated at 2150 C, and their microstructure and fractions of SiC polytypes in the porous SiC ceramics were evaluated. Figure 6 exhibits SEM micrographs of the porous SiC ceramics without Al-B-C additives sintered at 2150°C. In the case of submicron-sized p-SiC powder, only a few SiC grains were grown into plate-like shape. As for the porous SiC ceramics using micron-sized and coarse p-SiC powders, plate-like SiC grains were not grown without additives. 

Figure 2.4 Representative microstructures of steel-cutting grades of cemented tungsten carbide (a) 94%WC-6%Co alloy, submicron grain size, (b) 94%WC-6%Co alloy, medium grain size, (c) 86%WC-8% (Ti, Ta, Nb)C-6%Co alloy, medium grain size. The gray angular particles are WC, and the dark gray, rounded particles are solid-solution carbides. The white areas are cobalt binder. (Ref. 14).

The microstructures of the two samples (n=0.4), NO3-I and Cl-Br-2, are compared in Fig. 5. NO3-I was mainly composed of submicron particles, but large a lomerates were also formed. By contrast, Cl-Br-1 was composed of highly dispersed fine particles with uniform size less than 0.1 mm. These are noncrystalline mixtures as evident from Fig.4. The amorphous-like nature of MnOx-Zr02 appears to be originated from the growth process of hydroxides in the coprecipitation process. With an addition of base (OIT) to the aqueous solution of Mn(N03)2, hydroxide [Mn(OH)6] clusters formed would be bound together to grow into Mn(OH)2 crystallites. 

Flow-assisted methods typically utilize steric hindrance mechanisms in which microchannels or microstructures form barriers to move particles out of their streamlines and into a desired equilibrium position. The steric hindrance mechanism allows size separation of micron and submicron... 

Fig. 2 demonstrated the microstructures of Ni -AI2O3 membranes. It can be seen that the microstructure of both membrane surfaces composed of interconnected submicron particle size with less than I micron in size. The interconnected porosity where pores are connected to the surfeces of the membrane still appeared on both cases. However, it was noticed that a denser structure is obtained on the surface of membranes with alumina support sintered at 1200°C. Larger particle sizes along with a greater connection between particles were observed. 

Fig. 7.11 Microstmctures of the porous and fully dense spinel ceramics produced by sintering at 2 GPa and 795 °C. a and c SEM micrographs of the porous submicron structure of spinei ceramic derived from 200-nm-sized spinel powder, b SEM and d TEM Images of the microstructure of the fully dense nanosized spinel ceramics. Reproduced with permission from [49]. Cop5uight 2014, Elsevier...

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