Sir thing that often confused me as i have started with fixed composition C0 in principle the solidified material must contain same fixed composition e.g each grain and solidified region in microstructure must have same composition C0 as i started at beginning of solidification but solidified material possessed different compositions to C0.how does it seem logical mean i have added 40 atoms of A element and 60 atoms of B element after solidification i should have same atom ration in each region and grain but rather than i have 30 atoms of A and 70 atoms of B e.g similar different A/B atoms ratios in different regions and grains .normally this could be happened in non- homogeneous mixing of A and B atoms in melts .is this could be the reason in isomorphous alloy system as you explained? or some other reasons please explain
can the tie line be drawn at liquidous or solidus lines? even if we are drawing ...for example at liquidus line , Fa=0% so there is no meaning for Cs(dash) at 5:13. As Cs(dash) indicates the % of components in alpha phase and there is no alpha phase at that point. I mean , we can define alloy composition Co but not phase composition. what i interpreted is correct Sir?
This is a good question. Yes, there is a contradiction that if the fraction of the phase is zero how it can have a composition. However, this can be resolved if you think in terms of limits. So as you lower the temperature towards the solidus temperature the phase fraction of liquid tends to zero and the composition of the liquid phase tends to the limiting value CL indicated by the liquids line.
Sir on that point where you are saying that it will be 100% solid phase, according to tie line liquid fraction will also be present....but you didnot show it...why???
What is meant by the composition of liquid is something x% of Ni and composition of solid is something y% of Ni .. And how it's going to be change with the change in temperature
Respected sir, @15.13, the polycrystalline structure will compltely form at solidus line or at the point below the solidus line??? At solidus line when we draw the isotherm then some part of liquid phase is also present. Please clarify my doubt.
If you draw the isotherm (tie-line) at the solidus line then the lever arm opposite to the liquid is zero where the lever arm opposite to the solid is the entire lever arm itself. This indicates that solidification should complete at the solidus temperature.
Sir, I'm having a doubt about the concentration of solid. As you said the first formed solid will be having a composition of 80 wt% of nickel When temperature is reducing, the solid formed at each temperature will have a composition less than 80 wt % of nickel and the last solid formed will have the composition of 60 wt% of nickel . Everything is fine, but as the temperature reduces what will happen to the first formed solid's composition? Will it be same as 80 wt% of nickel?
No, in equilibrium the solid composition has to be uniform. This is achieved by diffusion in solid. This requires time. That is why we say that for equilibrium the cooling rate has to be very slow.
On Decreasing Temperature From liquid to solid When solidification completed fL=0 and f@=1 then On Increasing Temperature From solid to liquid When liquification completes fL=1 and f@=0 Or Something Else Happens? N what happens if we Start from two phase (L+@)
Both your statements are correct, but they happen at different temperatures. On cooling, solidification completes at the solidus temperature TS. On heating, liquifaction completes at the liquids temperature TL. If you start from 2 phase system (L+S) the temperature T will be between TL and TS, i.e., TL>T>TS. Depending upon whether you cool or heat from this temperature you will reach TS or TL. If you cool and reach TS you get fS=1 and fL=0. If you heat and reach TL you get fL=1 and fS=0.
CCP is the crystal structure of Cu and Ni. FCC is their lattice. CCP crystal structure = FCC lattice + 1 atom motif (at 000). Thus for crystal structure it is better to use CCP. However, one loosely uses FCC for crystal structure as well. I think I have fallen in the same trap.
Sir, In the first lecture - phase diagram introduction ,you said that Cu and Ni has ccp structure. Now in this lecture you mentioned it as fcc Sir, please clarify which one is correct
Sorry for creating confusion. The idea is to distinguish between crystal structure and lattice. FCC (Face-centred cubic) is a lattice. CCP (cubic close-packed) is a crystal structure. The relation between them is CCP crystal = FCC lattice + 1 atom motif. Because of this the centres of all atoms can be considered as lattice points. Thus often, in books and videos this distinction is not made and CCP crystal is also called as FCC crystal. So in one place I have an attempt to distinguish between these closely related concepts but here have fallen into the same trap of calling CCP as FCC!
At 4:35 I say and write 1500 for what is actually 1350.
thanks sir
Yes sir
Hi prof thanks for your lectures I'm student in USA and following your videos really good lectures,
Your videos are fantastic. Thank you so much
sir, you made it look so easy, thank you so much
thank you very much for taking your time to explain it so well!!
i have never watched such a great explanation
1350, rather than 1500, (according to Sir's diagram)
Amazing explaination.
thank you so much sir for this wonderful lecture
Thank you so much for these videoes, saved my grades :)
Sir thing that often confused me as i have started with fixed composition C0 in principle the solidified material must contain same fixed composition e.g each grain and solidified region in microstructure must have same composition C0 as i started at beginning of solidification but solidified material possessed different compositions to C0.how does it seem logical mean i have added 40 atoms of A element and 60 atoms of B element after solidification i should have same atom ration in each region and grain but rather than i have 30 atoms of A and 70 atoms of B e.g similar different A/B atoms ratios in different regions and grains .normally this could be happened in non- homogeneous mixing of A and B atoms in melts .is this could be the reason in isomorphous alloy system as you explained? or some other reasons please explain
Thank you Sir.
Which book you recommend which covers all of “introduction to Material sciences “ chapters in a same easy approach??
Nice explanation
Thanks Sir for easy explaines
Thanks from Egypt
thank you very much sir
can the tie line be drawn at liquidous or solidus lines? even if we are drawing ...for example at liquidus line , Fa=0% so there is no meaning for Cs(dash) at 5:13. As Cs(dash) indicates the % of components in alpha phase and there is no alpha phase at that point.
I mean , we can define alloy composition Co but not phase composition.
what i interpreted is correct Sir?
This is a good question. Yes, there is a contradiction that if the fraction of the phase is zero how it can have a composition. However, this can be resolved if you think in terms of limits. So as you lower the temperature towards the solidus temperature the phase fraction of liquid tends to zero and the composition of the liquid phase tends to the limiting value CL indicated by the liquids line.
@@introductiontomaterialsscience thank You Sir..for replying to our questions in right time as this helps us to understand further lectures.
Sir on that point where you are saying that it will be 100% solid phase, according to tie line liquid fraction will also be present....but you didnot show it...why???
SIR IS THERE AN EMAIL ID WHERE I CAN REACH OUT TO YOU IN CASE I HAVE DOUBTS??
What is meant by the composition of liquid is something x% of Ni and composition of solid is something y% of Ni ..
And how it's going to be change with the change in temperature
Respected sir,
@15.13, the polycrystalline structure will compltely form at solidus line or at the point below the solidus line??? At solidus line when we draw the isotherm then some part of liquid phase is also present. Please clarify my doubt.
If you draw the isotherm (tie-line) at the solidus line then the lever arm opposite to the liquid is zero where the lever arm opposite to the solid is the entire lever arm itself. This indicates that solidification should complete at the solidus temperature.
Thanku ❤
Sir, I'm having a doubt about the concentration of solid.
As you said the first formed solid will be having a composition of 80 wt% of nickel
When temperature is reducing, the solid formed at each temperature will have a composition less than 80 wt % of nickel and the last solid formed will have the composition of 60 wt% of nickel .
Everything is fine, but as the temperature reduces what will happen to the first formed solid's composition?
Will it be same as 80 wt% of nickel?
No, in equilibrium the solid composition has to be uniform. This is achieved by diffusion in solid. This requires time. That is why we say that for equilibrium the cooling rate has to be very slow.
@4:58...if my starting point has 1400°© ,then how would the liquidus temperature be greater than 1400°©...it should be less or not??
See that the whole analysis is taken at a particular alloy of 60% Ni
Thanks for pointing out the mistake.The liquidus temperature is 1350 and not 1500. I have made a mistake in writing it.
@@introductiontomaterialssciencemagnanimous and generous thanks sir
Good eyesight..
Thanks Sir ❤✌
What is the text book that you recommend to students to study from?
You can follow Materials Science and Engineering by V. Raghavan.
👍👍👍
Thankyou sir
On Decreasing Temperature
From liquid to solid
When solidification completed
fL=0 and f@=1
then
On Increasing Temperature
From solid to liquid
When liquification completes
fL=1 and f@=0
Or
Something Else Happens?
N what happens if we
Start from two phase (L+@)
Both your statements are correct, but they happen at different temperatures. On cooling, solidification completes at the solidus temperature TS. On heating, liquifaction completes at the liquids temperature TL. If you start from 2 phase system (L+S) the temperature T will be between TL and TS, i.e., TL>T>TS. Depending upon whether you cool or heat from this temperature you will reach TS or TL. If you cool and reach TS you get fS=1 and fL=0. If you heat and reach TL you get fL=1 and fS=0.
At 7:06 did you mean the 'lever rule' instead of 'tie line rule'?
You are right. I made a slip there. Thanks
love you
Sir, what is the difference between Crystallite size and Grain Size ?
I would like to consider them as synonyms.
Thanks sir
1000th like
tq sir
In the 1st lecture of phase diagram you told us sir that Cu and Ni are (CCP). But in this lecture you are telling us it's "FCC".??
CCP is the crystal structure of Cu and Ni. FCC is their lattice. CCP crystal structure = FCC lattice + 1 atom motif (at 000).
Thus for crystal structure it is better to use CCP. However, one loosely uses FCC for crystal structure as well. I think I have fallen in the same trap.
@@rajeshprasad101 Thanks for your reply sir.
@@rajeshprasad101 you are an excellent Teacher Sir 🙏
Did you mean TL is at 1350?
Yes, there is a mistake. It is 1350.
temperature is wrong at 4:33
Sir,
In the first lecture - phase diagram introduction ,you said that Cu and Ni has ccp structure. Now in this lecture you mentioned it as fcc
Sir, please clarify which one is correct
Sorry for creating confusion.
The idea is to distinguish between crystal structure and lattice. FCC (Face-centred cubic) is a lattice. CCP (cubic close-packed) is a crystal structure. The relation between them is CCP crystal = FCC lattice + 1 atom motif. Because of this the centres of all atoms can be considered as lattice points. Thus often, in books and videos this distinction is not made and CCP crystal is also called as FCC crystal.
So in one place I have an attempt to distinguish between these closely related concepts but here have fallen into the same trap of calling CCP as FCC!
Sir apko gussa Matt aanee Deena but apko sikhaa nahi ataa