Search

Herein, the effect of shortening the intercritical annealing (IA) time in a two‐step process "intercritical annealing and tempering (IAT)" on the microstructure and the mechanical properties of medium‐manganese steel (MMnS) made of Fe–0.05C–7Mn–1.5Cu–1.5Ni–1.5Al–1.5Si–0.5Mo (wt%) and containing copper‐rich (CRP) and Ni(Al/Mn) precipitates is investigated. The atom probe tomography (APT), electron backscattering diffraction (EBSD), and the synchrotron X‐ray diffraction (SYXRD) are used to study precipitation, phase microstructure evolution, the austenite stability, and deformation mechanisms. Shortening the IA step, which is carried out at 700 °C, from 2 min (IAT‐2) to 1 min (IAT‐1), results in a yield strength (YS) increment of around 218 MPa with less than 1% loss of ductility. While the enhanced yield strength in IAT‐1 is attributed to the four times higher precipitates' number density (n), the insignificant loss of ductility is attributed to the enhanced austenite stability factor from 4.5 to 9.2 in IAT‐2 and IAT‐1, respectively. The simultaneous increase in YS without ductility loss reflects that controlling the IA time is a promising strategy to overcome the yield strength and ductility trade‐off without the need for higher additions of costly alloying elements such as Ni, Al, Mn, and Cu. [ABSTRACT FROM AUTHOR]

Epidermal electronics have been attracting considerable attention due to their various potential applications in human‐computer interaction and health monitoring. However, because of the lack of a self‐adhesive and stable interconnect method between epidermal electronic sensors and rigid circuit boards, there remain difficulties in detecting body signals accurately by epidermal electronic sensors in daily life. Here, a 3D helical on‐skin interconnect is first introduced for epidermal electronics sensors. Inspired by the structure of the accordion lantern, the interconnect is composed of two electrospinning polyurethane (PU) fiber films and a helical metal fiber. The helical metal fiber acts as a stable conductor with stretchability, and the PU fiber film with polydimethylsiloxane provides a self‐adhesive substrate. Mechanical simulations and tests prove that the proposed interconnect can laminate conformally and unobtrusively onto human skin with excellent electrical stability (less than 0.5% electrical resistance change upon 100% elongation). Furthermore, based on the proposed interconnect, an all‐in‐one sensor‐interconnect design is presented, which endows the epidermal electronic systems with anti‐motion interference capability. A gesture identification wristband system realized by a single all‐in‐one strain sensor is demonstrated. Besides, a wireless on‐skin system that accurately monitors dynamic 12‐lead electrocardiographic is successfully built using all‐in‐one electrodes. [ABSTRACT FROM AUTHOR]