Atomic radius, crystal structure, electronegative and the most common valence ar
ID: 484816 • Letter: A
Question
Atomic radius, crystal structure, electronegative and the most common valence are given In tin following table for several elements for those that are nonmetals, only atomic radii are indicated Which of these elements would you expect to form the following with nickel; A substitutional solid solution Having complete solubility A substitutional solid solution of incomplete solubility An interstitial solid solution Cite the relative Burgers vector-dislocation line orientations for edge, screw, and mixed dislocations. For an FCC single crystal, would you expect the surface energy for a (100) plane to be greater or less than that for a (111) plane? Why? For a given material would you expect the surface energy to be greater than, the same as, or less than the grain boundary energy' Why? The grain boundary energy of a small angle grain boundary is less than for a high-angle one Why it this so? Briefly describe a twin and a twin boundary Cite the difference between mechanical and annealing twins. Carbon atom are situated in octahedral sites in FCC iron, and, for BCC iron. In tetrahedral sites. Compute the radius r of an impurity atom that will, just fit into a BCC tetrahedral site in.Explanation / Answer
1(a) a substitutional solid solution having complete solubility with nickel are as follows:
Pt is the only element that meets all of the criteria and thus forms a substitutional solid solution having complete solubility. At elevated temperatures Co and Fe experience allotropic transformations to the FCC crystal structure, and thus display complete solid solubility at these temperatures.
reasons-
: 1) the difference in atomic radii between Ni and the other element (DR%) must be less than ±15%, 2) the crystal structures must be the same, 3) the electronegativities must be similar, and 4) the valences should be the same, or nearly the same. Below are tabulated, for the various elements, these criteria.
Crystal DElectro-
Element DR% Structure negativity Valence
Ni FCC 2+
C –43
H –63
O –52
Ag +16 FCC +0.1 1+
Al +15 FCC -0.3 3+
Co +0.6 HCP 0 2+
Cr +0.2 BCC -0.2 3+
Fe -0.4 BCC 0 2+
Pt +11 FCC +0.4 2+
Zn +7 HCP -0.2 2+
(b) ) Ag, Al, Co, Cr, Fe, and Zn form substitutional solid solutions of incomplete solubility. All these metals have either BCC or HCP crystal structures, and/or the difference between their atomic radii and that for Ni are greater than ±15%, and/or have a valence different than 2+.
(c) C, H, and O form interstitial solid solutions. These elements have atomic radii that are significantly smaller than the atomic radius of Ni.
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