Problem 3.4 Part A

1 point possible (graded)

An isotropic alloy contains 5% by volume of a precipitate ofradius 10nm. Assume the primary metal is in a simple cubicarrangement. The alloy has a Young's modulus E=70GPa and aPoisson's ratio ν=0.35. If Γ=0.9J/m2 (the energy needed to cutthrough the precipitate lattice per unit surface area), andb=0.25nm, what is the precipitate spacing L in the alloy?

L (in nm):

  unanswered

Submit

You have used 0 of 20 attemptsSome problems have options such assave, reset, hints, or show answer. These options follow the Submitbutton.

SaveSave Your Answer

Problem 3.4 Part B

1 point possible (graded)

What is the shear stress required to move a dislocation past theprecipitates?

Ï„p (in MPa):

  unanswered

Submit

You have used 0 of 20 attemptsSome problems have options such assave, reset, hints, or show answer. These options follow the Submitbutton.

SaveSave Your Answer

Problem 3.4 Part C

1 point possible (graded)

Instead of introducing a precipitate into the primary metal,alumina, a dispersion compound is introduced.

Consider the dislocation shown below, which bows to a radius ofcurvature R at an angle θ between two particles a distance L apart.Use the expression for line tension in a dislocation, the geometryof the bowing dislocation, and the force resulting from the appliedshear stress to obtain an expression relating the applied shearstress and dislocation radius R. Express your answer in terms ofthe shear modulus G, the Burgers vector b, and the dislocationradius R.

(Hint: Draw the free body diagram for one of the particles. Theforce exerted by the stress on the dislocation is F=Ï„bL)

τ=  unanswered

Submit

You have used 0 of 20 attemptsSome problems have options such assave, reset, hints, or show answer. These options follow the Submitbutton.

SaveSave Your Answer

Problem 3.4 Part D

1 point possible (graded)

Based on your expression in Part C, what is the angle beyondwhich no additional applied stress is needed to move thedislocation past the particles? (In other words, at what angle doesthe maximum applied shear stress occur?

θ (in degrees):

  unanswered