$4\mathrm{.}14($a$)$ Consider that two infinitely long parallel positive

edge dislocations are viewed on a simple two$-$dimensional

x$,$y diagram such as Fig. $4\mathrm{.}36.$ One dislocation is located at

x$=0,$y$=0.$ Since this is a positive edge, its slip plane is

orizontal and contains the x axis. The other dislocation

also lies in a horizontal slip plane but this plane is sepa$-$

rated from that of the first dislocation by a vertical dis$-$

ance $($y$)$ of $10$b$,$ where b is the Burgers vector for both

dislocations. Now assume the first dislocation is fixed in

place and the second can move parallel to the x axis. With

he aid of a computer, plot F$\_($x$^(\text{'}))$ the x component of the

orce $($per unit length$)$ between the dislocations, as a func$-$

tion of x from x$=-240$nm to x$=+240$nm$.$ Let $\backslash$mu $=$

$86$GPa,b$=0\mathrm{.}248$nm$,$ and v$=0\mathrm{.}3.$

$($b$)$ Discuss the significance of the variation of F$\_($x$)$ with dis$-$

ance as the mobile dislocation is moved from x$=-\backslash$infty

$0=+\backslash$infty $.$