Fibrous grains

As the substrate temperature increases, the surface mobUity increases and the stmctural morphology first transforms to that of Zone T, ie, tightly packed fibrous grains having weak grain boundaries, and then to a full density columnar morphology corresponding to Zone 2 (see Fig. 7). 

Fig. 17. Structural diagram (51) for sputtered layers. Zone 1 is a porous structure consisting of tapered crystallites separated by voids. Zone 2 shows columnar grains, and Zone 3 has a recrystallized grain structure. Zone T is a transition structure consisting of densely packed fibrous grains.

Transition structure consisting of densely packed fibrous grains... 

Drawn wires and rolled sheet exhibit elongated fibrous grains, which can alleviate the embrittlement caused by interstitials. However, delamination can occur in heavily woriced materials during bending along the fiber boundaries. The splitting mode can be related to contaminated 100 cleavage planes [1.41,1.43]. 

Fibrous Grain-Aligned Silicon Nitrides (Large Grains) 355... 

Figure 8.6 shows the microstructure of the seeded (2 vol%) and tapesilicon nitride. Flere, the large fibrous grains with a diameter of a few micrometers and a... 

Figure 8.11 Schematic illustration of superplastic forging and superplastic sinter-forging techniques for fabricating fibrous-grain-aligned silicon nitrides.

Figure 8.12 Original and superplastically deformed silicon nitride specimens and their microstructures. In the deformed specimen, manyofthe fibrous grains are aligned alongthe...

When Sun et al. [42] used tn-stfuscanning electron microscopy (SEM) to observe the interaction between the cracks and the microstmctures, the interfacial debonding behavior between the large fibrous grains and the intergranular glass was seen to vary... 

Figure 8.17 In situ observations of crack interacting with the large fibrous grains.

In spite of the similar angles of incidence, the fibrous grain in the sample of 4.0wt% Y2O3-2.8 wt% AI2O3 failed transgranularly,... 

Figure 8.20 Schematic of alignment with tilted fibrous grains. Because ofthe wedge effects, tilted fibrous grains give rise to improved properties both in the strong (parallel to the alignment) and weak (perpendicular to the alignment) directions.

Fibrous Grain-Aligned Porous Silicon Nitrides 371... 

Figure 8.21 Microstructures of porous silicon nitride with large fibrous grain alignment (porosity 14%). Reprinted with permission from Ref [50] 2000, Blackwell Publishing, Inc.

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