I don't know how to calculate V, in the class's slides they said V is not depend on the shape of the hole. Can you guys explain more about it for me please. Sorry for my shitty English ^^

Mg can dissolve in Al to form a substitutional solid solution. Mg atoms are, however, bigger than Al atoms and each Mg atomo therefore distorts the surrounding Al lattice, i.e a coherency strain field effectively exists around each Mg atom. Using below equation estimate the misfit strain energy. Express the answer in kJ mol-1 and eV atom-1. What assumptions are implicit in this calculation ? AG = 4u82v = 1 The shear modulus of Al =25 GPa , the radius of Al atom = 1.43 x 10-10 m, the radius of amg atom =1.60 x 10-10m