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Shear stress required to bend a dislocation of radius R and burger vector b is P. What will be shear stress needed to turn a dislocation of radius 2R and burger’s vector 2b to bend the dislocation?

Correct Answer: P
Shear stress required to turn a dislocation is: τ=Gb/2R; where G is shear modulus, b is burger’s vector, R is the radius of dislocation. P=Gb/2R So if the radius is increased two times, and burger’s vector is also increased by two times, the net shear stress value will remain unchanged. G(2b)/2(2R)=Gb/2R=P

What is the resolved shear stress, when dislocation density in metal is equal to 1012m-2? Given that shear stress needed in the absence of dislocation is 500MPa. Numerical constant is 0.3 and shear modulus is 80GPa, burger vector is 1 nm.

An elliptical dislocation loop is gliding on plane ABCD of a single crystal of BCC material as shown in the following figure. It is gliding along the burger vector 'b'. Identify the correct statement.
Physics of Metals in Metallurgy mcq question image
P. Plane ABCD belongs to the family of (110).
Q. Burger vector 'b' belong to direction.
R. Dislocation has the edge character at point x and the screw character at point z.
S. Dislocation has the screw character at point x

A dislocation with Burger vector b1 will dissociate into two partial dislocations of burger vector b2 and b3 respectively; b1 -> b2 + b3 b1, b2, b3 are magnitude of burger vectors. So the reaction will occur only if __________

The Burgers vector b is the vector which defines the magnitude and direction of slip. For a pure edge dislocation, the Burgers vector is perpendicular to the dislocation line, while for a pure screw dislocation, the Burgers vector is parallel to the dislocation line.

Tresca or maximum-shear stress criteria assumes that yielding occurs when the maximum shear stress reaches a value of the shear stress in the uniaxial tension test. Assume the principal stress being σ1, σ2, σ3 where σ1 is largest, and σ3 is the smallest principal stresses. Find the value of minimum shear stress to cause yielding, given that yield stress in tension is equal to σo?

Find the shear strain in the material if the burger vector of dislocation is 0.1nm, average distance moved by dislocation is 1 micron, and dislocation density is 108 m-2?

For a dislocation with burger’s vector equal to b, the strain energy per unit length is X. What will be the strain energy with burger’s vector is equal to 3b?

Read the following information and answer the following questions below. In a class of 90 students, 80 students like burger or pizza.
62 like burger and 56 like pizza. How many like both burger and pizza?

Read the following information and answer the following questions below. In a class of 90 students, 80 students like burger or pizza.
62 like burger and 56 like pizza. How many like neither burger nor pizza?

Read the following information and answer the following questions below. In a class of 90 students, 80 students like burger or pizza.
62 like burger and 56 like pizza. How many like don't like burger?