Which of the following systems ie pair of metals would you e

Which of the following systems (i.e., pair of metals) would you expect to exhibit complete solid solubility? Justify your answers. Cr-V Mg-Zn Al-Zr Ag-Au Pb-Pt

Solution

In order for two metals to have complete solid solubility, the four rules of Hume - Rothery must be satisfied. They are

1) The difference between the elements must less than ± 15%

2) Both metals must have the same crystal structure

3) Both metals must have similar electronegativities

4) Both metals must have the same valences

For Chromium and Vanadium, the difference in their atomic radii is approximately 6%( Atomic radius of chromium is 0.125 mm and that of vanadium is 0.132 mm). They have the same crystal structure that is BCC. Valence of chromium is +3 and for vanadium it is +5 but it can exist as +3 also. Electronegativities of chromium and vanadium are 1.6 and 1.5 respectively. Thus they are completely soluble in each other. Answer is option (a) Cr - V