GND Map of alpha phase in Ti6Al4V alloy have been generated using EBSD.
Dislocations can be separated into two families, Geometrically Necessary Dislocations (GNDs) and Statistically Stored Dislocations (SSDs). When plastic deformation occurs, some dislocations allow for accommodating the lattice curvature which develops as a result of non-uniform strain at the crystal scale, those are called GNDs. The SSDs are on the contrary dislocations with no cumulative effect on the crystal lattice curvature. Local misorientations are induced by the curvature of the crystal lattice associated with GNDs mainly, and therefore the lattice curvature can be related to the presence of GNDs only. EBSD is an advantageous technique to estimate GND density based on the analysis of intragranular misorientations. SSD dislocation may be obtained by TEM methods. The calculation method of GND is described in the article 'About quantitative EBSD analysis of deformation and recovery substructures in pure Tantalum' doi:10.1088/1757-899X/89/1/012038
dislocation density will change during sample preparation for TEM method so it is not possible to obtain dislocation density by direct method (EBSD, ECCI or TEM)
I think XRD method using modified Williamson-hall is good method for this.
Dear Peyman, almost the same question was thoroughly discussed in my RG page by several interested people.(see in Questions)
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