e.g. the transformation of c-AlN into h-AlN considered to be as plastic deformation.
The main reason is the geometry of crystals (hcp vs bcc/fcc). By the way, it is a long thing to write here but I especially recommend to read:
Hull&Bacon
''Introduction to Dislocations'' 5th Ed. CHAPTER 6 and pp 109-118.
This source will make your mind clear and you will absouletely find the whole and perfect answer of your question.
With Best,
Emre...
@Vladimir yes agreed with you.
But the problem is the TiAlN material system which is a standard coating in hard coatings in machine tool industry, why plastically deform upon transformation into h-AlN. While it remain harder until it transform from c-AlN into h-AlN. Despite the fact that AlN in its intermediate state is FCC crystal. For FCC crystal there are 12 slip systems. The equilibrium state of AlN is hexagonal while for HCP crystal there are 3 slip systems. If you compare both crystals i.e., FCC and HCP, Dislocations movement, which is the primary cause of plastic deformation, will have more slip systems in FCC than HCP. But TiAlN remains harder when it has c-AlN domains or phases.
The main reason is the geometry of crystals (hcp vs bcc/fcc). By the way, it is a long thing to write here but I especially recommend to read:
Hull&Bacon
''Introduction to Dislocations'' 5th Ed. CHAPTER 6 and pp 109-118.
This source will make your mind clear and you will absouletely find the whole and perfect answer of your question.
With Best,
Emre...
Hi Hassan,
The likely explanation is the difference in Elastic modulus caused by the difference in electron bond density . Indentation induced deformation of these films include about 60% elastic deformation, hence the dependency of E on measured H values. IF the CRSS can be measured, w-AlN will show up higher values
Hi Kumar
Yes you correct. I will add to your reply that the difference also comes from the size difference between two phases. w-AlN has more space (bigger size) which might comes from the bonding concentration among the constituents elements, which is lesser compared to c-AlN.
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