Intergranular diffusion

Turner, M. E.., Further Studies on the Influence of Water Composition on the Dezincihcation of Duplex Brass Fittings , Proc. Soc. Water Treat. Exam., 14, 81 (1965) C.A., 63, 15984e Frade, G. and Lacombe, P., Influence of Intergranular Diffusion in the Kinetics of Dezincihcation of 70/30 Brasses Without Additions at 450-900 C , Compt. Rend., 260, 5022 (1965) C.A., 63, 5323c... 

Additional complexities arise whenever the permeating excess argon diffuses from intergranular boundaries to lattice sites or whenever the solid phase under-... 

Fig. 2. These diagrams represent (a) Dyson equation for diffusion propagator, (b) interaction vertex dressed by impurity and intergranular scattering, (c) Screened Coulomb interaction.

Molybdenum oxidises slowly in air at 350 C and readily at temperatures above 500 C, so that it cannot be used unprotected at such temperatures in air or other oxidising environments such as water vapour or carbon dioxide. The rate of oxidation depends on the temperature and the availability of the oxygen. It is rapid enough to cause ignition of very fine powder but not of the bulk metal. There is no intergranular penetration or diffusion of oxygen into the metal, and the surface film of oxide produced may be acceptable in some cases for components which are only required to operate for short periods at high temperatures. 

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