just try to establish if peak broadening occurs (in comparison with internal standard)

It is possible by full-profile method (Rietveld).

Respected ones

the deformation obtained from the broadness of the peaks , using reitveld analysis is of  nano order while ceramic have in general particle size in micron range, so the obtained results from XRD might be ineffective.

Yes, this is the right note that deformation is of nano order

Here is example of XRD Rietveld refinement results for SiC 6H

Crystallite Size k: 1 LVol-IB (nm) 111

Strain e0 0.0595

Lattice parameters

a (Е) 3.08345

c (Е) 15.12978

After high-energy treatment

Crystallite Size k: 1 LVol-IB (nm) 91.2

Strain e0 0.1

Lattice parameters

a (Е) 3.081460

c (Е) 15.12052

http://books.google.iq/books?id=WRg_AAAAQBAJ&pg=PA316&lpg=PA316&dq=measuring+of+plastic+deformation+in+ceramics&source=bl&ots=7_vjX6gmgR&sig=kruSmzdRf-cDddkC4fOtOZX5uuw&hl=ar&sa=X&ei=s4yFVMfKEoHuUPOmhKAD&ved=0CCEQ6AEwAA#v=onepage&q=measuring%20of%20plastic%20deformation%20in%20ceramics&f=false

On the macro scale you can measure residual stresses in a ceramic material using XRD if your equipment is set up for this (possibility to tilt the sample). You could detect a plastic deformation as a relaxation of the residual stresses. In the level of individual grains you can also measure stresses and relaxation of stresses but then you need to use electron diffraction (EBSD in an SEM). You can easily induce a plastic deformation in a ceramic by a hardness indent. A small indent gives only plastic deformation while a larger indent will also cause cracking (brittle failure).

Theoretically yes because the plastic deformation is going to induce changes in the dimensions of the crystal lattice,  By XRD  you can measure these changes and accordingly you can assess the extent of  strain. Nevertheless, how to chose the testing specimen and how to expose the plastically deformed part and how to scan it is another issue. 

There are standard XRD line broadening analysis to estimate grain size and microsstrain resulted from dislocations. You may try. If the plastic deformation is too small, the measured microstrain would be very low, so it is hard to quantify density fo dislocations produced by the plastic deformation.