The variations of the mechanical properties of the CoCrFeMnNi high entropy alloy (HEA) during groove cold rolling process were investigated with the aim of understanding their correlation relationships with the crystallographic texture. Our study revealed divergences in the variations of the microhardness and yield strength measured from samples deformed by groove cold rolling and conventional cold rolling processes. The crystallographic texture analyzed by electron back scattered diffraction (EBSD) revealed a hybrid texture between those obtained by conventional rolling and drawing processes. Though the groove cold rolling process induced a marked strengthening effect in the CoCrFeMnNi HEA, the mechanical properties were also characterized by an unusual decrease of the Young’s modulus as the applied groove cold rolled deformation increased up to about 0.5 before reaching a stabilized value. This decrease of the Young’s modulus was attributed to the increased density of mobile dislocations induced by work hardening during groove cold rolling processing.

In order to simulate micromachining of Ti-Nb medical devices produced in situ by selective laser melting, it is necessary to use constitutive models that allow one to reproduce accurately the material behavior under extreme loading conditions. The identification of these models is often performed using experimental tension or compression data. In this work, compression tests are conducted to investigate the impact of the loading conditions and the laser-based powder bed fusion (LB-PBF) building directions on the mechanical behavior of $\beta$-Ti42Nb alloy. Compression tests are performed under two strain rates (1 s${}^{-1}$ and 10 s${}^{-1}$) and four temperatures (298 K, 673 K, 873 K and 1073 K). Two LB-PBF building directions are used for manufacturing the compression specimens. Therefore, different metallographic analyses (i.e., optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), electron backscatter diffraction (EBSD) and X-ray diffraction) have been carried out on the deformed specimens to gain insight into the impact of the loading conditions on microstucture alterations. According to the results, whatever the loading conditions are, specimens manufactured with a building direction of 45${}^{\circ }$ exhibit higher flow stress than those produced with a building direction of 90${}^{\circ }$, highlighting the anisotropy of the as-LB-PBFed alloy. Additionally, the deformed alloy exhibits at room temperature a yielding strength of 1180 ± 40 MPa and a micro-hardness of 310 ± 7 HV${}_{0.1}$. Experimental observations demonstrated two strain localization modes: a highly deformed region corresponding to the localization of the plastic deformation in the central region of specimens and perpendicular to the compression direction and an adiabatic shear band oriented with an angle of ±45 with respect to same direction.

Due to their specific elastic properties (high stiffness to mass ratio), regular microstructure materials (architectural materials), are widely used in industry. This work deals with nondestructive evaluation of a 3D bi-material structure made of an architectural ABS polymer embedded in an Epoxy resin. The difficulty of applying ultrasonic techniques to bi-material structures lies in the fact that different phenomena coexist, such as diffraction effects caused by the periodicity and the nonlinear effects caused by the adhesion properties between matrix and fibers. A combination of techniques have, therefore, been applied. For this purpose, a series of measurements in reflection mode were first employed to measure the characteristic Bragg spectrum of a healthy sample and after compressive loadings. The results show that the damage disturbs the periodicity of the structure and consequently alters the Bragg spectrum. Then the nonlinear effects, possibly due to adhesion, are investigated using cross-modulation spectroscopy technique. The transducers used were chosen according to the thickness and the periodicity scale of the sample. Based on the preliminary results, higher harmonics and sidebands increase in amplitude with increasing damage has been realized. Finally, a total difference frequency distortion parameter TDFD was introduced as a damage indicator for quantifying the damage.