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A γ′ phase strengthened NiCoCrFeAlTiMoW alloy was prepared in a vacuum arc melting furnace, and X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile testing machine were used to investigate the coarsening behavior and the evolution law and mechanism of mechanical properties of the γ′ phase after 200 h long-term aging at 750, 850 ℃ and 950 ℃.The results show that γ′ phase remains spherical during the aging process when the aging time is extended, γ′ phase size gradually increases and the solidification phenomenon occurs at 750, 850 ℃ and 950 ℃. The alloy has a high diffusion activation energy with a value of 357 kJ/mol.This is mainly due to the fact that the matrix is a high entropy solid solution with complex composition, and the diffusion of Al and Ti atoms in the matrix becomes difficult due to the hysteresis diffusion effect. The yield strength of the alloy gradually increases after aging at 750 ℃, the yield strength after aging at 850 ℃ first increases and then decreases, and gradually decreases after aging at 950 ℃. The change in the yield strength of the alloy is caused by the increase in the size of the γ′ phase, which leads to a shift in the precipitation strengthening mechanism of the alloy.

Fe40Cr25Ni25Al5Ti5 (atom fraction/%) medium entropy alloys (MEAs) were prepared by a vacuum arc-melting furnace with a water-cooled copper mold, and the microstructure, mechanical properties and strengthening deformation mechanism of the alloy in solid solution and annealed states were studied by scanning electron microscopy (SEM), energy spectrometry(EDS), X-ray diffractometer (XRD), transmission electron microscopy(TEM) and tensile testing machine.The results show that the Fe40Cr25Ni25Al5Ti5 medium entropy alloy has FCC+BCC1+BCC2 triple-phase organization of solid solution state, with yield strength of 520 MPa, fracture strength of 852 MPa and elongation of 13%. After annealing at 600 ℃ for 2 h, the phase composition of the alloy has no change, the size of granular BCC2 phase increases, and the volume fraction of FCC zone and BCC zone has no change significantly. The yield strength is 668 MPa, the fracture strength is 1029 MPa, and the elongation is reduced to 9%. The strength of Fe40Cr25Ni25Al5Ti5 alloy originates from the synergistic effect of coherent strengthening, solid solution strengthening and phase boundary strengthening. Dislocation slips are the main deformation mechanism of alloy.

To date, only 25 cases of cerebral infarction following a bee or wasp sting have been reported. Due to its rarity, undefined pathogenesis, and unique clinical features, we report a case of a 62-year-old man with progressive cerebral infarction following bee stings, possibly related to vasospasm. Furthermore, we review relevant literature on stroke following bee or wasp stings.

The present torsional stiffness calculation and evaluation method only reflect the body stiffness and the torsion curves of the cross beam or threshold,it can hardly be used to evaluate the stiffness matching characteristics and the contribution of local region in body comprehensively. Aiming at this problem,a stiffness evaluation method based on regional contribution was proposed,with the strain energy and strain energy density as analyzed object. Meanwhile,a visualization method was proposed to visualize the regional contribution values. The methods above were applied to a domestic commercial vehicle. The contribution visualization model of body framework was established and the body stiffness matching characteristics were analyzed. The torsional stiffness matching was more reasonable after structure optimization. It indicates that the contribution visualization model can be used to evaluate stiffness matching characteristics of body and the contribution of each region intuitively,which gives guidance to structure stiffness matching design.