Void porosity

Fig. 13. Schematic representation of oxygen dissolving froin the oxide into the titanium metal at high temperatures. The interface is weakened with the formation of voids, porosity, and microcracks and with the embrittlement of the interfacial metal region [52).

A frequently used test has x-rays or gamma rays passing through a structure that absorbs distinctive flaws or inconsistencies in the material so that cracks, voids, porosity, dimensional changes, and inclusions can be viewed on the resulting radiograph. 

Sample Entry Initial Labile Block Density, Composition, vol.% g/cm Volume Fraction of Voids (Porosity) %... 

These are depicted schematically in Figure 18.4 in the case of metal A deposited on metal B. Bulk diffusion, as noted above, is the transfer of B into A or A into B through the crystal lattice. This is characterized by the coefficient D in the figure. Defect path diffusion is the migration along lattice defects such as grain boundaries, characterized by the coefficient D in the figure. Ordered A B, possible phases are indicated between the metals. Finally, Kirkendall void porosity is indicated and will be expected to be present if the interdiffusion rates from one metal to the other are not equal in both directions. 

Case Face angles Volume of unit-cell Volume of void Porosity (percent) Remarks... 

The analysis has shown that the SRP s with beryllium reflector flooded with lead-bismuth alloy are the most dangerous from the point of view of nuclear safety. The main reasons that can cause Kgfr variation due to a positive reactivity are air voids (porosity) being present in the SRP s cores and the possibility for these voids to be filled with water, as water reactivity worth in the SRP s core is -0.7 Peff / L. Thus it means that about 30 Liters of water have to be accumulated for K ff to be - 1 in the core. 

Discontinuities in products result from inherent material characteristics and from the manufacturing method. For example, casting, as a generic process, is more likely to produce material containing voids (porosity) compared with hot worked product such as plate where the voids are closed up by the mechanical work used to shape the product. 

Sample entry Initial labile block Density composition, vol% (gcnr3 Volume fraction of voids (porosity ) %... 

Radiography Voids, porosity, inclusions, and cracks Castings, forgings, weldments, and structural assemblies Detects internal flaws useful on a wide variety of geometric shapes portable provides a permanent record High cost insensitive to thin laminar flaws, such as tight fatigue cracks and delaminations potential health hazard... 

Magnetic particles Cracks, laps, voids, porosity and inclusions Castings. forgingSi and extrusions Simple inexpensive detects shallow subsurface flaws as well as surface flaws Useful for ferromagnetic materials only surface preparation required, irrelevant indications often occur operator-dependent... 

Ultrasonic testing Cracks, voids, porosity, inclusions and delaminations and lack of bonding between dissimilar materials Composites, forgings, castings, and weldments and pipes Excellent depth penetration good sensitivity and resolution can provide permanent record Requires acoustic coupling to component slow interpretation is often difficult... 

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