Checkpoint questions

Cite the primary differences between elastic, anelastic, and plastic deformation behaviors.

-Elastic deformation is time-independent and nonpermanent -anelastic deformation is time-dependent and nonpermanent -plastic deformation is permanent

Would you expect the surface energy to be greater than, the same, or less than the grain boundary energy?

-Greater -For grain boundaries, some atoms on one side of a boundary will bond to atoms on the other side; such is not the case for surface atoms. -fewer unsatisfied bonds along a grain boundary.

Rank the magnitudes of the diffusion coefficients from greatest to least for the following systems: N in Fe at 700˚C Cr in Fe at 700˚C N in Fe at 900˚C Cr in Fe at 900˚C

1) N in Fe at 900 2) N in Fe at 700 3) Cr in Fe at 900 4) Cr in Fe at 700

Of those metals listed in Table 6.3, which is the hardest? Why?

Material D bc it has the highest tensile strength

Explain why complete solid solubility may occur for substitutional solid solutions but not for interstitial solid solutions.

One requirement for the formation of a solid solution is that solute atoms fit into the crystal lattice without introducing significant lattice distortions -substitutional atoms completely replace -interstitial cause lattice distortions

Is it possible for three or more elements to form a solid solution?

Yes, it is possible for three or more elements to form a solid solution. For three or more elements, the same criteria apply as for two elements, as stipulated by the Hume-Rothery rules.

does the grain size number G increase or decrease with the decrease in the grain size?

increases

The surface energy of a single crystal depends on crystallographic orientation. Does this surface energy increase or decrease with an increase in planar density? Why?

surface energy decreases with an increase in planar density (more satisfied bonds, more atoms)