00:00till now we have looked at what are
00:01dislocation interactions
00:04now we will be looking at what are
00:05dislocation intersections and will get
00:07introduced to terms such as jogs and
00:10these chalks and kinks are nothing but
00:13a break in the dislocation line and the
00:16spread in the dislocation line are
00:17nothing but defect in the dislocation
00:19lines now let's look at how these breaks
00:21have been created on this dislocation
00:24so we have slip plane
00:27and let's mark at this location
00:32whose dislocation line is marked here
00:34and a burgers vector is along this plane
00:36and let's create a break on this
00:39so you can create a break on this
00:41dislocation line in this way where
00:43there is a break here on this
00:47and if you see that this break
00:50is not on the original slip plane so
00:53you have a dislocation line segment line
00:55on the slip plane one and
00:58another part of this dislocation line
01:00is on slip plane two and where the brake
01:02is not on the slip plate
01:05that is it is on the plane which is not
01:07a glide plane for this dislocation and
01:15so jogs are dislocation line
01:17segments or a breaks which are out of
01:19the original slip plane so this
01:26this break in the dislocation line is
01:28out of this original slip length and
01:29such breaks are called as strong
01:33there is another way of making a break
01:35and this break is shown over here
01:38so have right in this dislocation line
01:40and you can see that this break in this
01:44stays on the same slip plane
01:47and such kind of breaks on this
01:49dislocation line are called as kings
01:52so these are kings where
01:54dislocation line segment or a break
01:58remains in the same original
02:00plane or a glide plane
02:05are nothing but an extra segment in the
02:07dislocation and thus they increase the
02:10energy of dislocations
02:12these breaks increases the inertia of
02:16we know the energy of dislocation per
02:18unit length has to be alpha gb square
02:22and if you try to evaluate what is
02:25an energy of this job
02:27so you can say that energy of chalk can
02:28be equal to alpha gb square into v1
02:31where p1 is nothing but the length of
02:33the stroke so this length of the job
02:39the energy of a dislocation
02:43also these breaks in this dislocation
02:45line impede motion of the other
02:47dislocations and thus they result in the
02:51now how this breaks forms on this
02:55so this break forms on the dislocation
02:58intersection of dislocations
03:02this jog and king in more detail
03:06so here we have shown jog and kink
03:09and you can see this is a dislocation
03:13there is a break in this dislocation
03:16so you let's mark that you have glide
03:20and you have a glide plane here
03:24this break is on the
03:26other plane which is not a glide pin for
03:28this dislocation and such breaks in the
03:30dislocation line are called as chalks
03:34and kink are a break in dislocation
03:38which stays on the same slip plane let
03:42so you have a glide plane and this break
03:45remains on this same slip
03:47so this kind of breaks on the
03:48dislocation line are called as key
03:52now if you take any standard textbook
03:54and find out what is chalks and kings so
03:57the breaks on the dislocation lines in
03:59most of the text group
04:01are referred as chalks let us write that
04:13are called as chalks
04:17is a special case of a chalk
04:19so what do i mean by that so all the
04:21breaks on the dislocation line are
04:27remain on the same slip plane or a guide
04:30glide plane these are called as kings
04:42and kings are nothing but a subset of
04:52special case of jocks
04:54where breaks on this dislocation line
04:56stays on the same right plane
05:00now how these jogs and kings form
05:03as i mentioned earlier
05:07there is an intersection of dislocations
05:11and there is a rule which says that how
05:14these jobs and things should form so
05:16when two dislocations intersect
05:19each acquires a job equal in direction
05:22and length to the purchase vector of the
05:25let us read this again when true
05:27dislocation intersect
05:34and length to the purchase vector of the
05:37dislocation otherwise location
05:40so now let us understand this using
05:46so let us consider these two planes
05:49and let us consider an age dislocation
05:51with the bridges vector pointing in this
05:53direction and let's consider another
05:55edge dislocation in this slip plane
05:58with a purchase vector
06:00pointing towards down
06:02and if you look at this two cases
06:04carefully you have these edge
06:06dislocations having biggest vector v1
06:08and v2 so these purchase vector p1 and
06:09v2 are perpendicular to each other
06:14dislocations intersect how they will
06:17see that this term moves along this
06:20this dislocation moves down
06:23and when it intersects
06:29this dislocation when they intersect
06:31each will leave a step
06:33or a break on the dislocation line
06:36along the direction of the purges vector
06:39and the magnitude also will be the
06:42magnitude of the burgers vector of the
06:45so let's see this and
06:47if you apply this rule on this
06:52so you can see that there is a skip
06:55created on this dislocation b2
06:58along b1 direction so this step is along
07:00b1 direction let us mark here
07:04so this is along b1 direction
07:07and what will be the
07:08magnitude of this step
07:11so the magnitude of this step also will
07:13be equal to the burgess vector of this
07:16dislocation that is b1
07:18so this magnitude of this step will be
07:22b1 and this kind of steps which are
07:24moving out of the glide plane are called
07:26as job so you have a job
07:31on dislocation b2 because
07:42break on the dislocation
07:48so here there will not be any break
07:52on this dislocation b1 why because
07:55the purchase vector b2 is parallel to
07:58the tangent vector of this b1 let's look
08:04so let's mark the tangent vector for
08:08v1 so this will be tangent vector t1 and
08:14parallel to b2 and thus there will be no
08:22this this dislocation
08:24so there will be no steps created on
08:27now let us look at what is the nature of
08:31so for to find out the nature of chalk
08:33we need to find out what is a tangent
08:35vector and a burgers vector for this
08:38or a job let's find out the tangent
08:44so the tangent vector for this
08:46dislocation i am marking here
08:48so you have tangent vector
08:56as we know that this purchase vector for
08:58this dislocation will remain invariant
09:01this purchase vector will be always
09:03along this direction
09:06let us mark that so it will have a
09:08purchase vector b2 in this direction
09:11so this t1 t2 is perpendicular to b2 and
09:17jog has an age character
09:19so we have a job created because of the
09:22intersection of two dislocations
09:25or you can say that the job created on
09:27b2 because of because it intersected
09:29with this location b1
09:33and that has an edge character so let's
09:38understand this again so we have
09:41this dislocation p2 which is get
09:45intersected by this dislocation p1 and
09:47the jog will form along or the break
09:50will form on this dislocation line along
09:52b1 so we have break on this dislocation
09:55along v1 and what is the magnitude of
09:57that break that magnitude of that break
10:00magnitude of this purchase vector b1
10:03and this breaks are called as jaw
10:06now to find out the character of this
10:08shock what we have done we found out
10:10what is a tangent vector of this
10:14and the purges vector remains invariant
10:16for this dislocation so it
10:20this t2 is perpendicular to p2 and thus
10:24it has an edge character
10:28now let us look at another condition
10:34skew dislocations this is a this
10:36location nine which is marked by this
10:39red line and blue line and the purchase
10:42vectors are parallel to these
10:43dislocation lines this these are screw
10:47and if you look at this case carefully
10:52a skew dislocations having burgers
10:53vector perpendicular to each other now
10:55let's see that this dislocation b2 moves
10:58in this direction and b1 moves down
11:03when they intersect each other what kind
11:07so on b2 there will be a break because
11:15break will be along b1 direction
11:17so this will be along b1 direction
11:20and magnitude will be equal to
11:23that of b1 so we have a break on b2
11:26along b1 direction with a magnitude
11:29of b1 and this kind of bricks are called
11:36not on this same slip plane or a grid
11:39plane so such kind of breaks are called
11:43and now let's consider what will be the
11:45break on this dislocation b1
11:49so it will have a break
11:53on this dislocation p1
11:55because it intersect
11:58dislocation p2 so it will have a break
12:00along v2 direction so it will have a
12:03break along v2 direction
12:05with the magnitude of that break will be
12:08and this is nothing but a jog
12:13glide plane for this brake
12:17so this is a job because the brake is
12:20moving out of this grid planes
12:23and thus you have a jog's formation
12:25when two screw dislocations having
12:27burgess vector perpendicular to each
12:31now let's find out what is the nature of
12:34to do that what we have to find out what
12:37is a tangent vector and a purchase
12:39vector so let's look that also
12:43so i'm marking a tangent vector for b 2
12:46and it is in this direction
12:50and verges vector will be
12:52verges vector will be
12:54invariant for this dislocation and it
12:56will be in this direction
12:58so you can see that the tangent vector
13:01is perpendicular to b2
13:05so this is nothing but an age character
13:10you have an edge character or
13:13you have an edge character of this job
13:15which is formed on this screw
13:18now let's look at what is the nature of
13:22jog which is formed on this location v1
13:26and to do that we have to find out a
13:27tangent vector and a burgers vector
13:35find out a tangent vector so you have a
13:37tangent vector along a dislocation line
13:43and what will be the purchase vector the
13:47element same so it is b1 here
13:50now you can see that the tangent vector
13:54t1 is perpendicular to p1 and thus it
14:00so these jocks which are formed on this
14:04has an edge character both chokes so we
14:07have screw dislocation but the jocks
14:10on them has an edge character so this
14:13edge character cannot move on any slip
14:17plane and thus it stops the movement
14:23dislocations and thus it results in the
14:25strain hardening of the material
14:28now let's look at some other cases
14:35these age dislocations
14:38having burgess vector b1 and p2 and in
14:41this case you can see the purchase of
14:43the p1 is parallel to p2
14:46now let's see when they intersect
14:48what kind of breaks they form
14:51so let's see that this dislocation is
14:53moving along this direction and
14:56this dislocation is moving along this
15:03the break will be on
15:08b2 direction so it will be along b2
15:10direction with a magnitude of this
15:12purchase vector so let's mark it here so
15:15you form a break along
15:21with a magnitude so magnitude of this
15:30and now let's look at
15:34what's the step on this
15:38dislocation so you have a step which is
15:41created on b2 which will be along b1
15:44direction so this step which is created
15:46along b1 direction with a magnitude
15:54let's find out what is the nature of
16:02on the same slip plane for both b1 and
16:04b2 and thus these are nothing but kings
16:14are formed that is these kings are born
16:16by because b1 and b2 intersected each
16:21and let's find out what is the nature of
16:23these kicks let's find out the nature of
16:25king formed on this b1 dislocation
16:29find it out so to do that we
16:34tangent vector so we have tangent vector
16:42what's the purchase vector so purchase
16:44vector will remain invariant for this so
16:46it will be along this
16:48direction only so you have tan generator
16:50t1 which is parallel to purchase vector
16:55it has a screw nature
16:59kink has a screw nature
17:02so this is an edge dislocation
17:04and the kink formed on it has a screw
17:08similarly let's find out what is the
17:11nature or nature of this kink on the
17:15to do that find out what is a tangent
17:20so we are finding out a tangent vector
17:21here so tangent vector is in this
17:23direction and b 2 will be along the same
17:26direction so we have t 2
17:31v2 and thus this is also a screw nature
17:35so this kink which has formed on this p1
17:42now let's look at another condition
17:51and a screw dislocation v1
17:54b1 perpendicular to p2 its q and h
17:59of these dislocations
18:01v1 is perpendicular to b2 and let's see
18:03that this moves in this directions
18:06and let's find out when they intersect
18:08what they form what kind of breaks they
18:14the brick will form along b2 along the
18:17direction of b2 so it has formed along
18:18the direction of b2 with a magnitude
18:23with a magnitude equal to b2 and thus
18:26this is nothing but a kick because this
18:28break is on the same slip plane
18:35for b2 so you have a break which will
18:38form along b1 direction so you have a
18:40break which has formed along d1
18:42direction with a magnitude equal to b1
18:49this break is out of the slip plane and
18:53so we have a job formed on this age
18:56dislocation and you have king form on
19:01now let's find out what is the nature of
19:04jogs and king let us find out for a job
19:07first let us find out for job
19:11so let's find out what is a tangent
19:16so you have tangent vector t one
19:18and you have a purchase vector
19:23we have birches vector b2 which is
19:26perpendicular to this tangent vector
19:33similarly let's find out what is
19:36the nature of this break or kink
19:39which has formed on this dislocation b1
19:48going in this way for this dislocation
19:51and you have a purchase vector which is
19:56so you have tangent vector d1 parallel
19:59to purchase vector p1
20:05the king which has formed on this
20:07b1 has a screw nature
20:09so these were the some of the cases
20:11which we have seen when this location
20:13intersect how the kings and jogs form
20:16and what are their natures whether they
20:18are obscure nature or an age nature now
20:22see how this movement of jocks takes
20:24place so we have seen that the breaks on
20:27the dislocation line are called as
20:29and now let's see how these jocks move
20:33so we have seen this case where you have
20:35a screw dislocation here let's consider
20:40this is a screw nature this is also has
20:44a screen nature but the break on this
20:46that is pp dash has an edge
20:51so let's find it out how
20:53we are finding out the nature of this
20:56break so we have tangent vector which is
20:58going in this way and you can see this
21:00is a screw nature where we have biggest
21:02vector in this direction
21:07this is a screw dislocation and it has
21:09formed a break on this so you have
21:11purchase vector along this direction
21:14so you have a purchase vector along this
21:16direction and the tangent vector is
21:17perpendicular so the pp dash
21:19has an age nature let us write that down
21:27now when this dislocation screw
21:29dislocation want to move or glide on
21:33as you know that this pp dash cannot
21:38on any plane because it has an edge
21:40nature so this pp dash can
21:43glide on this plane that is
21:48but it cannot collide on this
21:51p e p dash q dash and q
21:54so this dislocation has to move along
21:57this direction what it has to do
22:00break which has an age nature has to
22:05because this cannot glide because this
22:07is not a glide plane for this
22:09pp dash which is a break which is
22:11nothing but a job on this
22:13screw dislocation why it cannot glide
22:17on this plane that is p p q dash and q
22:22the purchase vector and the tangent
22:26on this plane so for
22:29an edge dislocation to glide on any
22:31plane what is the condition that the
22:33tangent vector and vertices vector
22:41job can glide only on p p dash r dash
22:44and r plane but it cannot glide on p e q
22:49thus if i want to move this dislocation
22:51along this way what it has to do
22:53we have seen that when
22:59on some other plane which is parallel to
23:02it can do by climbing
23:05so there must be a client here
23:08occurring so we have to
23:10climb this edge dislocation along this
23:12direction to move this screw dislocation
23:19if if it would have been just a screw
23:21dislocation it can glide on any slip
23:23plate but now there is a break which has
23:26been created that is a chalk on this
23:27screw dislocation which has an edge
23:30it cannot move so freely so thus
23:33the movement of the screw dislocation is
23:36impeded because of the formation of such
23:39jogs on this previous location and if it
23:42has to move it has to
23:44move by a process of climb and the climb
23:46involves formation of
23:50the movement of this kind of screw
23:52dislocation become difficult
23:54now let us look at how this
23:58so this movement can occur like let us
24:00say this is a jog which has an edge
24:02character and has to move forward in
24:05what it does is it forms vacancies
24:09so these jogs on this crew dislocation
24:12has which has an age nature
24:15if they want to move forward
24:17there will be formation of vacancies
24:20and these jobs act as a source or sinks
24:23for vacancies when they move
24:25under the influence of stress or
24:28now let's look at this condition we have
24:35so you have we have seen a dislocation
24:39now on this dislocation line there will
24:43and this dislocation line is now bend
24:49so this dislocation line
24:58vacancy formation or vacancy
25:00accumulation at this region and this
25:04this part is called as job in this
25:06dislocation line let me mark that also
25:25a vacancy accumulation over here and you
25:30get accumulated at here you can see that
25:36so this location gets climbs up and we
25:39have seen this scenario when the vacancy
25:41joins an extra half plane the
25:43dislocation can climb up
25:45and when this vacancies joins this extra
25:48half plane there is a formation of jokes
25:51so as i mentioned you the jogs can
25:56by climb process and this climb process
26:01or annihilation of practices so
26:03formation or annihilation of vacancies
26:04takes place during the climb process of
26:09involves a stress and thermal activation
26:13the climb process involves the stress
26:15and thermal activation to move these
26:19so this is an important thing
26:21which we have seen for chalks and kicks
26:24and with this i will stop here
