In this study, we examined the effect of charging current density on the hydrogen embrittlement (HE) of MEA and the associated HE mechanisms using electron backscattered diffraction (EBSD). Results show that MEA is susceptible to HE, but is stronger than as-rolled and 3D-printed Cantor alloy and stainless steel. The HE susceptibility of MEA decreases with increasing current density. Ductile fracture with transgranular dimples switches to intergranular brittle fracture with clear slip bands in the interior of grains. EBSD results uncovered that hydrogen facilitates localized slips and deformation twins. Hydrogen-enhanced localized plasticity and hydrogen decohesion are the possible HE mechanisms.

We systematically studied the characteristics and influence of free layer thickness in magnetic tunnel junction (MTJ) with a perpendicular synthetic antiferromagnetic (p-SAF) reference layer on 8-inch wafer. The results show clearly that there is an optimal thickness of free layer to achieve the highest tunneling magnetoresistance (TMR) ratio of as high as 80.5% and 53.7% with perpendicular and in-plane magnetic field, respectively, while the resistance-area product (RA) reaches also highest value of 21.1 Ω*μm². The thickness range of CoFeB to obtain perpendicular magnetic anisotropy (PMA) is determined. The variation of the magnetic moment of free layer indicates that the three-dimensional (3D) sensors can be designed by varying the thickness of the free layer and be controlled by the perpendicular and in-plane components through annealing under the in-plane magnetic field.

The welded joints of high/medium entropy alloys (H/MEAs) have shown sound mechanical properties, indicating high promise for the industrial application of this new type of metal alloy. However, these joints possess either relatively low strength or low ductility. In this paper, we used ultrasonic-assisted laser welding to weld CrCoNi MEA with the nitrogen as shielding gas. The results showed that the tensile strength of the joint at room and cryogenic temperature is 686 MPa and 1071 MPa, respectively. The elongation at room and cryogenic temperature is 26.8% and 27.7%, respectively. The combination of the strength and ductility in our joints exceeds that of other welded H/MEA joints. We attributed this excellent combination to the refined dendrite, the solution of nitrogen into the matrix, and the low stacking fault energy of the CrCoNi MEA. The findings in this paper not only provide a novel way to weld H/MEAs with high strength and ductility, also are useful for additively manufacturing the high-performance component of H/MEAs.