Give a detailed explanation;

When sufficient boron $(>0\mathrm{.}75$ at$.\%)$ is added to $N{i}_{3}Al($simple cubic Bravais lattice$)$ the $\{420\}$

$CuK{K}_1$ lines on a Debye$-$Scherrer powder pattern become broadened. Assuming this

broadening is due to a tetragonal distortion $($expansion$)$ of the unit cell, by how much would the

lattice have to become tetragonal $($i$.$e$.,$ the value of c$)$ before separate $(420)$ and $(024)$ lines were

resolved. The lattice parameter for unalloyed $N{i}_{3}Al$ is $3\mathrm{.}56.$ Assume that the camera has a

diameter of $57\mathrm{.}3mm$ and that lines have to be separated by $0\mathrm{.}6mm$ to be resolvable.

Al

$Ni$