Yield stress during uniaxial deformation strongly depends upon crystallographic texture in Mg, because it depends on easily operating basal slips. So varying the texture changes the average Schmid factor of basal slips impacting the yield stress. Similarly, is there any effect of texture on Micro-Vickers hardness as the hardness test creates a complex state of stress enabling multiple slips locally?
With regard to the general question of the crystallographic orientation dependence of the hardness and the mechanical hardening (be it in the case of mechanical indentation or also other forming- or material testing methods), it must first be noted that the Schmid factor alone has only a relatively low significance as soon as the mechanical load case is tensorially more complex than in the case of uniaxial tensile or compressive loading (as described in textbooks for uniaxial conditions).
The reason for this is that in more complex load cases, the mechanical boundary conditions of the often somewhat more complicated applied imposed deformation state (such as indents) can never be achieved with a single glide or twin system alone, so that multiple slips occur immediately. In such cases, the Tailor-Bishop-Hill factor is more helpful for estimating the orientation dependence of such test methods and, above all, the orientation-specific strain hardening must be taken into account.
As a result, the differences in indentation between the different texture components ( crystallographic orientations) are usually somewhat smaller than would be expected from the single crystal tensile test and the use of Schmid factors alone.
A little more information on this can be found here:
(a) indent mechanics and orientation dependence:
https://www.dierk-raabe.com/reprints/nanoindentation/
(b) crystal kinematics pertainign to these questions:
https://damask.mpie.de/
and
https://www.dierk-raabe.com/nanoindentation-and-pillar-compression/
https://www.dierk-raabe.com/indentation-pile-up/
(c) class notes on the mechanics:
https://www.dierk-raabe.com/teaching/
Good luck!
Dierk Raabe Thank you sir for giving your valuable time to discuss my query. I am going through the article you suggested for an in-depth understanding of deformation behavior during micro and nano-indentation.
As mentioned by Prof. Dierk Raabe plastic strain field in nanoindentation is very complex thus multiple slip systems are active simultaneously. Due to the above, there are no big differences in hardness for different orientations. Interesting work on this topic was done by Vlassak and Nix in 1994, investigating the influence of single-crystals orientation on their elastic properties and hardness. They observed that even for zinc (c/a ratio = 1.856), the difference in hardness between the different orientations was only 20%. For most metals, these differences are much smaller. You can find the work of Vlassak and Nix here: Article Measuring the Elastic Properties of Anisotropic Materials by...
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