Investigation of the texture and microstructure evolution around a nanoindent close to an individual grain boundary.

We present a study about the dependence of the evolution of orientation patterns around nanoindents on the presence of a grain boundary. In prior work, the plasticity of single crystalline Ti-5Al-2.5Sn (wt%) near α-alloy has been quantified by a combination of crystal lattice orientation mapping, instrumented sphero-conical nanoindentation, and measurement of the resulting surface topography. By iteratively improving the match of corresponding crystal plasticity finite element simulation of the indentation the adjustable parameters of the constitutive description are identified [1]. This methodology is extended by carrying out indentations close to individual grain boundaries whose inclinations were measured by focused ion beam milling. Texture measurements are performed using a high resolution electron back-scatter diffraction (EBSD) technique for the acquisition of texture mappings around the indents [2] [3]. Finally, the experimentally observed nanoindentation pile-up patterns and textures are compared to corresponding predictions obtained by a tridimensional crystal plasticity finite element simulation of a bicrystal indentation using the previously calibrated single crystal constitutive law.
[1] Zambaldi C. et al. (2012). J. Mater. Res. 27, 356-367.

[2] Wang et al., (2004) Acta Materialia, 52, 2229-2238.

[3] Zaafarani, N. et al., (2008) Acta Materialia, 56(1), 31-42.




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