In this study,the effect of severe plastic deformation on the Mg grain refinement and recovery mechanism was investigated.Technical pure magnesium was deformed at room temperature by cycling extrusion-compression(CEC)...In this study,the effect of severe plastic deformation on the Mg grain refinement and recovery mechanism was investigated.Technical pure magnesium was deformed at room temperature by cycling extrusion-compression(CEC)process up to large deformation.Several steps of deformation have been used by applying 1,2 and 4 passes of CEC giving a total effective plastic strain ofε=3.1.Mechanical and structural properties of Mg in initial state and the states after successive steps of deformation were investigated.The mechanical properties were determined by microhardness and compression tests at room temperature.The structural investigations involved light microscope observations,electron back scattered diffraction and texture measurements by X-ray diffraction.It was found that the CEC process refines the grain size down to 6.4μm and reduces strong rolling texture components.However,only the first two passes had a strong effect on mechanical properties while a larger number of CEC cycles(above 4)led to failure of the samples with a small effect on hardness.This observation correlates with texture evolution indicating a more random orientation distribution that slows down the typical for hep metals rapid work hardening.It was found that the CEC process activated twin dynamic recrystallization in deformed Mg.This process led to the formation of new randomly oriented grains inside the twinned areas and as a consequence it reduced the strong rolling texture components.展开更多
In this work,the microstructure of titania coating fabricated on the surface of hydrostatically extruded titanium grade 4 with the use of the micro-arc oxidation method was studied.The surface topography and microstru...In this work,the microstructure of titania coating fabricated on the surface of hydrostatically extruded titanium grade 4 with the use of the micro-arc oxidation method was studied.The surface topography and microstructure investigations performed with atomic force microscopy and scanning and transmission electron microscopy revealed that,by using an Na_(2)HPO_(4)electrolyte,a well-adherent porous coating is produced on the top surface and side walls of the extruded rod.The distribution of chemical elements was analyzed by using energy dispersive X-ray spectroscopy.The chemical elements dissolved in the electrolyte(Na,P and O)incorporated into the coating.Sodium locates preferentially in the outer part of the coating,while phosphorus and oxygen are distributed throughout the whole coating.The most relevant finding shows that a grain refinement caused by a hydrostatic extrusion provoked an increase in density of high-angle grain boundaries(HAGB),which in turn secured the formation of a continuous amorphous layer close to the substrate.The presence of this layer compensates for the effect of anisotropic substrate,producing a comparable and homogenous microstructure with a large number of micropores.展开更多
基金The project was performed within the activity(11.11.180.653)of the Department of Materials Science and Non-Ferrous Metals Engineering at AGH-UST Krakow,Poland.
文摘In this study,the effect of severe plastic deformation on the Mg grain refinement and recovery mechanism was investigated.Technical pure magnesium was deformed at room temperature by cycling extrusion-compression(CEC)process up to large deformation.Several steps of deformation have been used by applying 1,2 and 4 passes of CEC giving a total effective plastic strain ofε=3.1.Mechanical and structural properties of Mg in initial state and the states after successive steps of deformation were investigated.The mechanical properties were determined by microhardness and compression tests at room temperature.The structural investigations involved light microscope observations,electron back scattered diffraction and texture measurements by X-ray diffraction.It was found that the CEC process refines the grain size down to 6.4μm and reduces strong rolling texture components.However,only the first two passes had a strong effect on mechanical properties while a larger number of CEC cycles(above 4)led to failure of the samples with a small effect on hardness.This observation correlates with texture evolution indicating a more random orientation distribution that slows down the typical for hep metals rapid work hardening.It was found that the CEC process activated twin dynamic recrystallization in deformed Mg.This process led to the formation of new randomly oriented grains inside the twinned areas and as a consequence it reduced the strong rolling texture components.
基金financially supported by the Institute of Metallurgy and Materials Science of the Polish Academy of Sciences within the statutory work Z-4/2021partly supported by the EU Project POWR.03.02.00–00-I004/16。
文摘In this work,the microstructure of titania coating fabricated on the surface of hydrostatically extruded titanium grade 4 with the use of the micro-arc oxidation method was studied.The surface topography and microstructure investigations performed with atomic force microscopy and scanning and transmission electron microscopy revealed that,by using an Na_(2)HPO_(4)electrolyte,a well-adherent porous coating is produced on the top surface and side walls of the extruded rod.The distribution of chemical elements was analyzed by using energy dispersive X-ray spectroscopy.The chemical elements dissolved in the electrolyte(Na,P and O)incorporated into the coating.Sodium locates preferentially in the outer part of the coating,while phosphorus and oxygen are distributed throughout the whole coating.The most relevant finding shows that a grain refinement caused by a hydrostatic extrusion provoked an increase in density of high-angle grain boundaries(HAGB),which in turn secured the formation of a continuous amorphous layer close to the substrate.The presence of this layer compensates for the effect of anisotropic substrate,producing a comparable and homogenous microstructure with a large number of micropores.
