Circle the element that would you expect to form a substitut
     Circle the element that would you expect to form a substitutional solid solution (having complete solubility) with Nickel?  Label each type of defect as Point, Linear or Planar. Circle the defect with the greatest interfacial energy.  External surface  Self-interstitial  Edge dislocation  Interstitial solid solution  Vacancy  Domain Wall  Determine the magnification of the micrograph if the scale bar length is measured to be 10 mm.  Optical micrograph of Hiparco 50 Hs alloy subjected to an annual of 1200 degree C for 1 hr. Average grain size of about 161 mu m. 
  
  Solution
For complete substitutional solid solutions
Two conditions ( known as Hume--Rothery rule ) are
1. Two metals must have same similar crystal structures.
which in case of your problem all three have FCC structure.
2. The differece in there atmoic radii should be less than 15%
for silver(Ag) =
=(.1445-.1246)/.1246=15.97%
for pt platinum
=(.1387-.1246)/.1246=11.31%
so only platinum will make complete substitutional solid solutions.
2)
External Surface-Planer
Self Intersitial - Point
Edge dislocation-Line
Intersitial solid solution-Point
Vacancy-Point
Domain wall-point

