@article {1501,
	title = {In-plane and out-of-plane deformation at the sub-grain scale in polycrystalline materials assessed by confocal microscopy},
	journal = {Acta Materialia},
	volume = {169},
	year = {2019},
	pages = {260{\textendash}274},
	abstract = {<p>
	High-resolution digital image correlation (HR-DIC) techniques have become essential in material mechanics to assess strain measurements at the scale of the elementary mechanisms responsible of the deformation in polycrystalline materials. The purpose of this study is to demonstrate the use of laser scanning confocal microscopy (LSCM) coupled with DIC techniques to deepen knowledge on the deformation process of a polycrystalline nickel-based superalloy at room temperature. The LSCM technique is capable of detecting both in-plane and out-of-plane strain localization within slip bands at the sub-grain level. The LSCM observations are consistent with previous in-situ scanning electron microscopy (SEM) studies: The onset of crystal plasticity occurs primarily near \&Sigma;3 twin boundaries with macroscopic loading in the elastic domain (macroscopic stress as low as 80\% of the 0.2\% offset yield strength (Y.S. 0.2\% )). This intense irreversible strain localization occurs with either a high Schmid factor (\&mu; \&gt; 0.43) or a significant elastic modulus difference between the pair of twins (\&Delta;\&Epsilon; \&gt; 100 GPa). In the plastic deformation domain, transgranular slip activity following slip systems with the highest Schmid factor is mostly responsible for the deformation at the grain level, thus leading to strain percolation. The simultaneous in-plane and out-of-plane deformation assessment via the HR-LSCM-DIC technique was found to be essential for the identification of active slip systems. Finally, the HR-LSCM-DIC technique enabled the quantification of the glide amplitude involved in the three-dimensional shearing process at the grain level that solely in-plane measurements cannot provide.
</p>
},
	keywords = {High Resolution-Digital Image Correlation (HR-DIC), In-situ tensile testing, Laser scanning confocal microscopy (LSCM), Nickel-based polycrystalline superalloy, Strain localization},
	issn = {13596454},
	doi = {10.1016/j.actamat.2019.03.001},
	url = {https://doi.org/10.1016/j.actamat.2019.03.001},
	author = {Liu, J. H. and Vanderesse, N. and Stinville, J. C. and Pollock, T. M. and Bocher, P. and Texier, D.}
}
@article {1436,
	title = {Measurements of plastic localization by heaviside-digital image correlation},
	journal = {Acta Materialia},
	volume = {157},
	year = {2018},
	pages = {307{\textendash}325},
	abstract = {<p>
	In polycrystalline metallic materials, quantitative and statistical assessment of the plasticity in relation to the microstructure is necessary to understand the deformation processes during mechanical loading. Plastic deformation often localizes into physical slip bands at the sub-grain scale. Detrimental microstructural configurations that result in the formation and evolution of slip bands during loading require advanced strain mapping techniques for the identification of these atomically sharp discontinuities. A new discontinuity-tolerant DIC method, Heaviside-DIC, has been developed to account for discontinuities in the displacement field. Displacement fields have been measured at the scale of the physical slip bands over large areas in nickel-based superalloys by high resolution scanning electron microscopy digital image correlation (SEM DIC). However, conventional DIC methods cannot quantitatively measure plastic localization in the presence of discontinuous kinematic fields such as those produced by slip bands. The Heaviside-DIC technique can autonomously detect discontinuities, providing information about their location, inclination, and identify slip systems (in combination with orientation mapping). Using Heaviside-DIC, discontinuities are physically evaluated as sharp shear-localization events, allowing for the quantitative measure of strain amplitude nearby the discontinuities. Measurements using the new Heaviside-DIC technique are compared to conventional DIC methods for identical materials and imaging conditions.
</p>
},
	keywords = {Discontinuities measurements, High resolution digital image correlation, Ren{\'e} 88DT polycrystalline superalloy, Scanning electron microscopy, Slip band offset, Slip band shearing, Slip system identification, Strain localization},
	issn = {13596454},
	doi = {10.1016/j.actamat.2018.07.013},
	url = {https://doi.org/10.1016/j.actamat.2018.07.013},
	author = {Bourdin, F. and Stinville, J. C. and Echlin, M. P. and Callahan, P. G. and Lenthe, W. C. and Torbet, C. J. and Texier, D. and Bridier, F. and Cormier, J. and Villechaise, P. and Pollock, T. M. and Valle, V.}
}
