http://zig.onera.fr/~devincre/perso_html/Documents/Queyreau_10.pdf

Orowan strengthening and forest hardening superposition examined by dislocation dynamics simulations

Highly efficient solar cells with sustainable performance under severe mechanical deformations are in great demand for future wearable power supply devices. In this regard, numerous studies have progressed to implement flexible architecture to high-performance devices such as perovskite solar cells. However, the absence of suitable flexible and stretchable materials has been a great obstacle in the replacement of largely utilized transparent conducting oxides that are limited in flexibility. Here, a shape recoverable polymer, Noland Optical Adhesive 63, is utilized as a substrate of perovskite solar cell to enable complete shape recovery of the device upon sub-millimeter bending radii. The employment of stretchable electrodes prevents mechanical damage of the perovskite layer. Before and after bending at a radius of 1 mm, power conversion efficiency (PCE) is measured to be 10.75% and 10.4%, respectively. Additionally, the shape recoverable device demonstrates a PCE of 6.07% after crumpling. The mechanical properties of all the layers are characterized by nanoindentation. Finite element analysis reveals that the outstanding flexibility of the perovskite layer enables small plastic strain distribution on the deformed device. These results clearly demonstrated that this device has great potential to be utilized in stretchable power supply applications.

Mechanically Recoverable and Highly Efficient Perovskite Solar Cells: Investigation of Intrinsic Flexibility of Organic–Inorganic Perovskite

For the purpose of obtaining the appropriate heat input in the simulated weld CGHAZ of the hot-rolled V–N microalloyed high strength S-lean steel, the microstructural evolution, hardness, and toughness subjected to four different heat inputs were investigated. The results indicate that the hardness decreases with increase in the heat input, while the toughness first increases and then decreases. Moderate heat input is optimum, and the microstructure is fine polygonal ferrite, granular bainite, and acicular ferrite with dispersive nano-scale V(C,N) precipitates. The hardness is well-matched with that of the base metal. Moreover, the occurrence of energy dissipating micromechanisms (ductile dimples, tear ridges) contributes to the maximum total impact energy. The detrimental effect of the free N atoms on the toughness can be partly remedied by optimizing the microstructural type, fraction, morphologies, and crystallographic characteristics. The potency of V(C,N) precipitates on intragranular ferrite nucleation without MnS assistance under different heat inputs was discussed.

Effect of welding heat input on microstructures and toughness in simulated CGHAZ of V-N high strength steel

Mechanical and Structural Degradation of LiNixMnyCozO2 Cathode in Li-Ion Batteries: An Experimental Study

Deformation-induced martensite in austenitic stainless steels: A review

Electron backscattering diffraction analysis of secondary cleavage cracks in a reactor pressure vessel steel

On the identification of stress–strain relation by instrumented indentation with spherical indenter

This paper compares the results of two approaches of instrumented indentation for characterization of mechanical properties of HVOF coatings. Three types of HVOF sprayed coatings (Cr3C2-NiCr, WC-Co, (Ti, Mo)(C,N)-NiCo) were investigated by the means of isolated nanoindentation and grid indentation methods. The results of the isolated indentation revealed hardness and elastic modulus of the individual phases in very good agreement with the corresponding bulk material. The grid indentation method, based on statistical evaluation of a large number of indentations, was influenced by the carbide-matrix interface, which gave rise to a third peak apart from the two peaks corresponding to the carbides and metallic matrix. As a consequence, the bimodal Gaussian fit was insufficient and a trimodal fit had to be used. The results extracted from low load grid nanoindentations were quite close to the results of isolated indentations whereas higher load grid nanoindentation revealed overall properties of the coating.

Comparison of Isolated Indentation and Grid Indentation Methods for HVOF Sprayed Cermets

Deformation-induced martensite in metastable austenitic steel was characterised by the grid nanoindentation method. Distribution of nanohardness was found out in specimens with different martensite volume fractions. Bimodal distribution of hardness was only slightly affected by the values obtained on or near γ-α’ phase boundary. This approach was verified by independent phase identification using electron back scattered diffraction.

Characterisation of strain‐induced martensite in a metastable austenitic stainless steel by nanoindentation

This paper provides a useful guide how to characterize material anisotropy by nanoindentation. Hardness and indentation modulus of austenitic stainless steel (grade A304) were characterized by instrumented indentation at the grain scale (at low indentation load and depth of penetration). We applied the grid indentation method on an area containing several grains with different crystallographic orientation which was simultaneously characterized by electron back-scatter diffraction. Hardness and indentation modulus dependencies on crystallographic orientation were then evaluated and compared with single crystal Young’s modulus and finite element simulations.

Jiří Nohava

Papers

Electron backscattering diffraction analysis of secondary cleavage cracks in a reactor pressure vessel steel

On the identification of stress–strain relation by instrumented indentation with spherical indenter

Comparison of Isolated Indentation and Grid Indentation Methods for HVOF Sprayed Cermets

Characterisation of strain‐induced martensite in a metastable austenitic stainless steel by nanoindentation

Characterization of Anisotropy in Hardness and Indentation Modulus by Nanoindentation