The dynamic tensile properties and microstructural evolution of an extruded EW75 magnesium alloy deformed at ambient temperature and different high strain rates(from 1000 to 3000 s^(-1))along extrusion direction(ED)we...The dynamic tensile properties and microstructural evolution of an extruded EW75 magnesium alloy deformed at ambient temperature and different high strain rates(from 1000 to 3000 s^(-1))along extrusion direction(ED)were investigated by Split Hopkinson Tension Bar(SHTB).The corresponding deformation mechanisms,texture evolution and microstructure changes were analyzed by optical microscope(OM),electron backscatter diffraction(EBSD)and transmission electron microscope(TEM).The results show that the extruded EW75 magnesium alloy along ED exhibits a conventional positive strain rate sensitivity that the dynamic flow stresses increase with in creasing strain rate.Texture measurements show that after dynamic tension,the initial weak texture of extruded EW75 magnesium alloy tansforms to a relatively strong<10-10>//ED texture with increasing strain rates.The microstructural analysis demonstrates that dislocation motion are main deformatin mode to accommodate dynamic tensile deformation at high strain rates.In addition,the interactions of dislocation-dislocation and dislocation-second phase lead to the in crease of flow stress and strain hardening with increasing strain rate.展开更多
The corrosion behaviors of Mg–7Gd–5Y–1Nd–0.5Zr alloys after T5 treatment under(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray condition were investigated by weight loss rates,residual mechanical properties,scann...The corrosion behaviors of Mg–7Gd–5Y–1Nd–0.5Zr alloys after T5 treatment under(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray condition were investigated by weight loss rates,residual mechanical properties,scanning electron microscope(SEM),X-ray Diffraction(XRD)and potentiodynamic polarization tests.The corrosion degree of Mg–7Gd–5Y–1Nd–0.5Zr alloys in Ca(NO_(3))_(2)salt spray was very shallow by corrosion morphology and the corrosion route was extended along the surface in texture-like shape,while the alloy in NaCl and(NH4)_(2)SO_(4)salt spray were major local corrosion and there were serious corrosion pits on the surface.The weight loss rates in(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray was respectively 0.4147,0.1618 and 0.0725 mg/(cm2 d−1).The results of residual mechanical properties indicated that the corrosion order in salts spray of Mg–7Gd–5Y–1Nd–0.5Zr alloys is NH4SO4>NaCl>Ca(NO_(3))_(2),which was consistent with the results of potentiodynamic polarization tests.The type of the salts will play a vital role in the initiation of the corrosion of EW75 alloy when they are used in the atmosphere environments.Inorganic salts with the smaller PH value after dissolution will have a stronger impact on the corrosion of EW75 magnesium alloys.展开更多
基金The authors would like to thank Professor Kui Zhang,Beijing General Research Institute for Nonferrous Metal,for providing EW75 magnesium alloy for this work and acknowledge the funding from the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.17KJD430006)Scientific and Technological Innovation Team Foundation of Wuxi Institute of Technology(No.30593118001)Scientific Research Project of Wuxi Institute of Technology(No.ZK201901).The help of EBSD experiment provided by Yukyung Shin from Helmholtz-Zentrum Geesthacht is gratefully acknowledged.
文摘The dynamic tensile properties and microstructural evolution of an extruded EW75 magnesium alloy deformed at ambient temperature and different high strain rates(from 1000 to 3000 s^(-1))along extrusion direction(ED)were investigated by Split Hopkinson Tension Bar(SHTB).The corresponding deformation mechanisms,texture evolution and microstructure changes were analyzed by optical microscope(OM),electron backscatter diffraction(EBSD)and transmission electron microscope(TEM).The results show that the extruded EW75 magnesium alloy along ED exhibits a conventional positive strain rate sensitivity that the dynamic flow stresses increase with in creasing strain rate.Texture measurements show that after dynamic tension,the initial weak texture of extruded EW75 magnesium alloy tansforms to a relatively strong<10-10>//ED texture with increasing strain rates.The microstructural analysis demonstrates that dislocation motion are main deformatin mode to accommodate dynamic tensile deformation at high strain rates.In addition,the interactions of dislocation-dislocation and dislocation-second phase lead to the in crease of flow stress and strain hardening with increasing strain rate.
基金Foundation item:National Natural Science Foundation of China(No.51204020)National Basic Research Program of China(No.2013CB632202,No.2013CB632205).
文摘The corrosion behaviors of Mg–7Gd–5Y–1Nd–0.5Zr alloys after T5 treatment under(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray condition were investigated by weight loss rates,residual mechanical properties,scanning electron microscope(SEM),X-ray Diffraction(XRD)and potentiodynamic polarization tests.The corrosion degree of Mg–7Gd–5Y–1Nd–0.5Zr alloys in Ca(NO_(3))_(2)salt spray was very shallow by corrosion morphology and the corrosion route was extended along the surface in texture-like shape,while the alloy in NaCl and(NH4)_(2)SO_(4)salt spray were major local corrosion and there were serious corrosion pits on the surface.The weight loss rates in(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray was respectively 0.4147,0.1618 and 0.0725 mg/(cm2 d−1).The results of residual mechanical properties indicated that the corrosion order in salts spray of Mg–7Gd–5Y–1Nd–0.5Zr alloys is NH4SO4>NaCl>Ca(NO_(3))_(2),which was consistent with the results of potentiodynamic polarization tests.The type of the salts will play a vital role in the initiation of the corrosion of EW75 alloy when they are used in the atmosphere environments.Inorganic salts with the smaller PH value after dissolution will have a stronger impact on the corrosion of EW75 magnesium alloys.
