Measurement of the local mechanical properties in polycrystalline samples using spherical nanoindentation and orientation imaging microscopy

High Throughput Assays for Additively Manufactured Ti-Ni Alloys Based on Compositional Gradients and Spherical Indentation

“…They should also allow generalization for the elasticplastic indentation and produce meaningful indentation stressstrain curves with an initial elastic regime followed by transition into an elastic-plastic regime. In recent work [6,7,10, Fig. 1 Schematic of the conventional approach (top row), and how this can be augmented with a high throughput (HT) approach (bottom row) to explore materials with different combinations of compositional and/or process conditions.…”

“…If the indentation length scales are well below the typical grain size, relevant microstructure attributes would include the grain orientation and local dislocation density in the indented zone [7,10,36,37]. If the indentation zone cover several grains, the relevant microstructure features might include grain size, shape, and orientation distributions in the indented zones [7].…”

“…In this regard, recent advances in spherical indentation stress-strain protocols [6][7][8][9][10][11][12][13] offer many advantages. The conventional practices in indentation testing rely on sharp indenters and analyze the unloading segments after imposing substantial amounts of indentation loads (or depths) to arrive at estimates of modulus and hardness [14][15][16].…”

Mechanical Characterization of Mesoscale Interfaces Using Indentation Techniques

“…This fraction can then be interpreted as the fractional increase in the local slip resistance at the indentation site in the deformed sample. 75,76 The viability of these new protocols was recently demonstrated by Vachhani et al 22 on a selected set of grain boundaries in a coarse-grained Al sample. Figure 4 summarizes the results of this study.…”

“…In order to separate these contributions, Y ind is first mapped out as a function of the crystal lattice orientation in an annealed sample (with the same chemistry as the sample of interest). 75,76 In prior work, we have demonstrated that this functional dependence can be captured efficiently using generalized spherical harmonics, 77 and subsequently used to predict the value of the indentation yield strength in the annealed condition for any new grain orientation of interest. Having this estimate of the indentation yield strength in the annealed condition then allows one to compute the increase in the indentation yield strength in the deformed sample (after making measurements in the deformed sample) and express this increase as a fraction of the annealed yield strength.…”