Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G...Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).展开更多
This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied an...This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.展开更多
The AZ80 magnesium(Mg)alloy cabin component with high strength and excellent ductility was developed by W-shaped channel extrusion(WCE)at 350℃ and subsequent T6 heat treatment.The effect of WCE process on the microst...The AZ80 magnesium(Mg)alloy cabin component with high strength and excellent ductility was developed by W-shaped channel extrusion(WCE)at 350℃ and subsequent T6 heat treatment.The effect of WCE process on the microstructure and mechanical properties of the alloy was experimentally investigated,and the age-hardening behavior with microstructure evolution during heat treatment was revealed.Due to the introduction of multi-stage asymmetric extrusion and severe shear deformation along the annular channel,the average grain size of the WCE extruded alloy could be effectively refined to 4.7μm.Besides,theβphase particles were dynamically precipitated from the fine grain boundaries during extrusion,which hindered the grain growth,but worsen the material plasticity.After T6 treatment,the properties of component were eventually improved to a yield strength(YS)of 218 MPa and ultimate tensile strength(UTS)of 344 MPa with elongation(EL)of 14.5%.It was revealed that the rod/lath-and needle-shaped continuousβphase(CP)with finer size precipitated after T6 treatment was more effective in hindering the movement of dislocations and strengthened the alloy than lamellar discontinuousβphase(DP).The dispersed phase precipitated in the grains,the annihilation of dislocations,the uniformly distributed grains and the re-dissolution ofβphase particles at initial grain boundaries after T6 treatment greatly contributed to the ductility of alloy.Moreover,the T6 treatment also promoted the basal plane of most grains which were re-arranged to the extrusion direction,which promoted the possibility of non-basal slip activation and further improved the elongation of the alloy.As a result,the UTS and YS of the final component increased by 10%and the EL increased by 7%,respectively.展开更多
The Hirota equation can be used to describe the wave propagation of an ultrashort optical field.In this paper,the multi-component Hirota(alias n-Hirota,i.e.n-component third-order nonlinear Schrodinger)equations with ...The Hirota equation can be used to describe the wave propagation of an ultrashort optical field.In this paper,the multi-component Hirota(alias n-Hirota,i.e.n-component third-order nonlinear Schrodinger)equations with mixed non-zero and zero boundary conditions are explored.We employ the multiple roots of the characteristic polynomial related to the Lax pair and modified Darboux transform to find vector semi-rational rogon-soliton solutions(i.e.nonlinear combinations of rogon and soliton solutions).The semi-rational rogon-soliton features can be modulated by the polynomial degree.For the larger solution parameters,the first m(m<n)components with non-zero backgrounds can be decomposed into rational rogons and grey-like solitons,and the last n-m components with zero backgrounds can approach bright-like solitons.Moreover,we analyze the accelerations and curvatures of the quasi-characteristic curves,as well as the variations of accelerations with the distances to judge the interaction intensities between rogons and grey-like solitons.We also find the semi-rational rogon-soliton solutions with ultrahigh amplitudes.In particular,we can also deduce vector semi-rational solitons of the ncomponent complex mKdV equation.These results will be useful to further study the related nonlinear wave phenomena of multi-component physical models with mixed background,and even design the related physical experiments.展开更多
Investigated in the present paper is a fifth-order nonlinear evolution(FONLE)equation,known as a nonlinear water wave(NLWW)equation,with applications in the applied sciences.More precisely,a traveling wave hypothesis ...Investigated in the present paper is a fifth-order nonlinear evolution(FONLE)equation,known as a nonlinear water wave(NLWW)equation,with applications in the applied sciences.More precisely,a traveling wave hypothesis is firstly applied that reduces the FONLE equation to a 1D domain.The Kudryashov methods(KMs)are then adopted as leading techniques to construct specific wave structures of the governing model which are classified as W-shaped and other solitons.In the end,the effect of changing the coefficients of nonlinear terms on the dynamical features of W-shaped and other solitons is investigated in detail for diverse groups of the involved parameters.展开更多
文摘Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).
文摘This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.
基金supported by the Shanxi Provincial Science and Technology Cooperation and Exchange Project(No.202104041101033)the special fund for Science and Technology Innovation Teams of Shanxi Province+1 种基金the Shanxi Province's Key Core Technology and Common Technology Research and Development Special Project(No.2020XXX015)the Ningbo Natural Science Foundation(Project 2021J231 and 2021J232).
文摘The AZ80 magnesium(Mg)alloy cabin component with high strength and excellent ductility was developed by W-shaped channel extrusion(WCE)at 350℃ and subsequent T6 heat treatment.The effect of WCE process on the microstructure and mechanical properties of the alloy was experimentally investigated,and the age-hardening behavior with microstructure evolution during heat treatment was revealed.Due to the introduction of multi-stage asymmetric extrusion and severe shear deformation along the annular channel,the average grain size of the WCE extruded alloy could be effectively refined to 4.7μm.Besides,theβphase particles were dynamically precipitated from the fine grain boundaries during extrusion,which hindered the grain growth,but worsen the material plasticity.After T6 treatment,the properties of component were eventually improved to a yield strength(YS)of 218 MPa and ultimate tensile strength(UTS)of 344 MPa with elongation(EL)of 14.5%.It was revealed that the rod/lath-and needle-shaped continuousβphase(CP)with finer size precipitated after T6 treatment was more effective in hindering the movement of dislocations and strengthened the alloy than lamellar discontinuousβphase(DP).The dispersed phase precipitated in the grains,the annihilation of dislocations,the uniformly distributed grains and the re-dissolution ofβphase particles at initial grain boundaries after T6 treatment greatly contributed to the ductility of alloy.Moreover,the T6 treatment also promoted the basal plane of most grains which were re-arranged to the extrusion direction,which promoted the possibility of non-basal slip activation and further improved the elongation of the alloy.As a result,the UTS and YS of the final component increased by 10%and the EL increased by 7%,respectively.
基金supported by the National Natural Science Foundation of China(Nos.11925108 and 11731014)
文摘The Hirota equation can be used to describe the wave propagation of an ultrashort optical field.In this paper,the multi-component Hirota(alias n-Hirota,i.e.n-component third-order nonlinear Schrodinger)equations with mixed non-zero and zero boundary conditions are explored.We employ the multiple roots of the characteristic polynomial related to the Lax pair and modified Darboux transform to find vector semi-rational rogon-soliton solutions(i.e.nonlinear combinations of rogon and soliton solutions).The semi-rational rogon-soliton features can be modulated by the polynomial degree.For the larger solution parameters,the first m(m<n)components with non-zero backgrounds can be decomposed into rational rogons and grey-like solitons,and the last n-m components with zero backgrounds can approach bright-like solitons.Moreover,we analyze the accelerations and curvatures of the quasi-characteristic curves,as well as the variations of accelerations with the distances to judge the interaction intensities between rogons and grey-like solitons.We also find the semi-rational rogon-soliton solutions with ultrahigh amplitudes.In particular,we can also deduce vector semi-rational solitons of the ncomponent complex mKdV equation.These results will be useful to further study the related nonlinear wave phenomena of multi-component physical models with mixed background,and even design the related physical experiments.
文摘Investigated in the present paper is a fifth-order nonlinear evolution(FONLE)equation,known as a nonlinear water wave(NLWW)equation,with applications in the applied sciences.More precisely,a traveling wave hypothesis is firstly applied that reduces the FONLE equation to a 1D domain.The Kudryashov methods(KMs)are then adopted as leading techniques to construct specific wave structures of the governing model which are classified as W-shaped and other solitons.In the end,the effect of changing the coefficients of nonlinear terms on the dynamical features of W-shaped and other solitons is investigated in detail for diverse groups of the involved parameters.