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The hot deformation behavior of TiAl alloy is analyzed by combining the true stress–strain curve and microstructure analysis. The results show that the flow stress of TiAl alloy presents the characteristics of work hardening-dynamic softening, it increases with the increase of strain rate and decreases with the increase of temperature. Based on the true stress–strain curves, the flow stress of TiAl alloy under different deformation conditions is predicted by hyperbolic sinusoidal formula. In addition, the effects of deformation temperature and strain rate on the microstructure evolution of TiAl alloy are revealed. In the process of hot compression deformation, dynamic recrystallization and γ → α , β → α phase transformation occurs. During tensile deformation, TiAl alloy exhibits super-plasticity, which is mainly due to grain rotation and coordinated deformation of β phase.

The flow behavior of a novel Cr-Si alloyed hot stamping steel (Cr-Si steel) at elevated temperature was investigated via isothermal compression tests on a Gleeble-3500 thermomechanical simulator with a temperature range of 600 ∼ 900 °C and a strain rate range of 0.1 ∼ 10 s ^−1 . Subsequently, the Arrhenius-type constitutive model, comprising strain compensation, was established in accordance with the friction and adiabatic heating corrected stress-strain curves. Furthermore, the predictability and prediction accuracy of the constitutive model were verified. The results reveal that at a constant strain rate, the flow stress of the Cr-Si steel initially increases as the strain increases before tending to stabilize, owning to the combined effects of work hardening and dynamic recovery. The peak flow stresses decrease as the temperatures increase and the strain rates decrease. The constitutive model can accurately predict the elevated temperature constitutive relationship of the Cr-Si steel during the hot stamping process.

Recently, topological chains have attracted extensive attention because of their simple structure, rich physics and important applications. In this work, we theoretically and experimentally uncover that the abundant topological phases of periodic trimer chain composed of one kind of meta-atom, namely split-ring resonators (SRRs), can be flexibly controlled by tunning the rotation angle of SRRs. On the one hand, we study the rotation controlled phase transition between two topological distinguished trimer chains with inversion symmetry. The generation of symmetric edge states can be easily controlled in this phase transition. On the other hand, the topological phases of the trimer chain broken inversion symmetry is demonstrated. Especially, the rotation controlled asymmetric edge states are observed in this process. So, rotation provides a new degree of freedom to manipulate edge states in the trimer chain composed of SRRs. The results in this work not only provide a flexible way to observe controlled edge states, but also provide a good research platform for designing other topological models with complex coupling distributions.

Since the quantum concept of parity-time (PT) symmetry has been introduced into the conventional inductor–capacitor resonance, strategies based on exceptional points (EP) based strategies redefine our understanding of sensitivity limitation. This considerable enhancement of sensitivity originated in exploration of the non-Hermitian physics in photonics, acoustics and electronics, which exhibits a substantial application to the miniaturization of implanted electronic sensors in medicine field. By continuously accessing the EP, the spectral response of reader ∆ ω follows a dependency of Δ ω ∼ κ ^2/3 to a weakly coupling rate (| κ | ≈ 0), which may approach the theoretical limit of sensitivity in a second-order EP system. In this paper, we experimentally demonstrate a high-order (higher than second-order) PT symmetric system for weak coupling detection, in which a third-order EP can be employed to fulfill the sensitivity of Δ ω ∼ κ ^1/2 . Particularly, we introduce the incoming wave as an effective gain to balance the loss and obtain a pair of purely real eigenfrequencies. There are absence of imaginary parts despite corresponding real parts shifts dramatically by using a neutral resonator, without a broadening of the reflection spectrum so that maintaining a high resolution on the sensitivity. This work may reveal the physical mechanics of a small perturbation at a high-order EP and promote applications in implanted medicine devices.

In order to investigate the law and mechanism of selective oxidation of Quenching and Partitioning (Q&P) steel under different annealing parameters, the sensitivity of alloy elements added in Q&P steel to the annealing parameters was explored. Galvanizing experiments of QP steel were carried out at different annealing temperatures(770 °C and 730 °C) and different holding times(180 s and 300 s). The concentration change of selective oxidation element and the alloying element distribution in the coating were analyzed by Glow Discharge Optical Emission Spectrometer (GDOES), the morphology of surface oxides and inhibition layer were observed by Scanning Electron Microscope (SEM). The results showed that higher annealing temperature(770 °C) and longer annealing time(300 s) could both increase the concentration of Mn and Si on the surface of Q&P steel, improve the oxidation degree of steel surface, thin the inhibition layer, and lead to more leakage plating and deterioration of surface coating quality. The Mn depth profiles showing a parabolic trend and reaching its maximum value at about 20 nm below the surface, while the concentration of Si gradually decreases from the surface to the interior. The selective oxidation of Si and Mn are more sensitive to the annealing temperature than the annealing time.