In general, at any temperature the magnitudes of Db and Ds relative to the diffusivity through defect-free lattice D1 are such that_________ (Db and Ds are grain boundary and surface diffusivity)

In general, at any temperature the magnitudes of Db and Ds relative t

1.	In general, at any temperature the magnitudes of Db and Ds relative to the diffusivity through defect-free lattice D1 are such that_________ (Db and Ds are grain boundary and surface diffusivity)
A.	Db>Ds>D1
B.	Db<Ds<D1
C.	Db>D1>Ds
D.	Ds>Db>D1
Answer» E.

Discussion

No Comment Found

Related MCQs

Grain boundary diffusion makes a significant contribution to the total flux when___(Db and D1 are the diffusivities through the grain boundary and defect free lattice and ȣ, d are the effective thickneβ and grain size).
At high temperatures diffusion through the lattice is rapid and g*Dp / D1 is very small so that the dislocation contribution to the total flux of atoms is_______ (Dp, D1 are diffusivity through pipe and defect free lattice and g is the cross-sectional area of ‘pipe’ per unit area of matrix).
Find the frequency factor of the following grain boundary diffusion, if the activation energy is given as 90KJ/mol and the diffusivity at the grain boundary at 1071K is given as 49*10-6m2/sec?
The dislocations effectively act as pipes along which atoms can diffuse with a diffusion coefficient 2.5mm2/sec. Calculate the apparent diffusivity if the cross-sectional area of pipe per unit area of matrix is given as 10-1? (If D1 (diffusivity through defect free lattice) is given as 5mm2/sec)
The rate at which atoms diffuse along different boundaries is_________
In FCC metals it is generally found that ___
The jump frequency for atoms migrating along the defects is higher than that for diffusion in the lattice.
The relative magnitudes of Db*ȣ and D1*d are most sensitive to_______(Where Db and D1 are the diffusivities through the grain boundary and defect free lattice and ȣ, d are the effective thickness and grain size)
The diffusion through the lattice can be ignored under certain circumstances. Which among the following condition should be satisfied for the same if the diffusivity through a defect free lattice is given as 2.5 mm2/sec and the grain size is given as 5mm? (Consider the diffusivity through the grain boundary as 2mm2/sec)
In a diffusion couple made by welding together two metals, A and B.A-atoms diffusing along the boundary will be able to penetrate much deeper than atoms which only diffuse through the lattice.

In general, at any temperature the magnitudes of Db and Ds relative to the diffusivity through defect-free lattice D1 are such that_________ (Db and Ds are grain boundary and surface diffusivity)

Discussion

No Comment Found

Related MCQs

Reply to Comment