Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedicalfields.Recent advancements in modern powder metallurgy techniques,such as spark plasma technique(SPS),...Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedicalfields.Recent advancements in modern powder metallurgy techniques,such as spark plasma technique(SPS),have enabled achieving near-net-shape products with tailored properties and decreased in-process oxidation.However,improving their mechanical and physical properties require further enhancement.In this study,a novel Mg-0.7Ca alloy was produced using SPS process.The effects of process parameters such as sintering time and additive type on the microstructural evolutions,phase arrangements,and mechanical and physical properties of the consolidated materials were investigated through various characterization techniques.Full-dense samples were produced from 60-minute ball-milled powder mixtures through spark plasma sintering at 420℃ for 7,10,and 13 min under 38 MPa of externally applied pressure.The obtained samples were then characterized using Field Emission Scanning Electron Microscopy(FESEM),Electron Backscatter Diffraction(EBSD),X-ray Energy Dispersive Spectroscopy(EDS),and X-ray Diffraction(XRD)analysis methods,as well as mechanical tests including compression strength and micro-hardness measurements.The results indicated that while improved densification behavior is observed in paraffin-contained samples,relatively better compression properties are achieved in starch-contained alloys.It is also found that the phase arrangement of the starch-contained samples includes higher fractions of the secondary phases such as oxides and residual carbons,which can positively affect the mechanical strength,despite decreased hardness.The microstructural characterizations showed an intensified thermomechanical response of the materials in both groups via increased sintering time.However,the competition between the influencing parameters causes scattered strengthening behavior and texture in the consolidated samples.Detailed discussions about the densification behavior,texture,and obtained characteristics were also included.展开更多
The main purpose of the current study was to investigate the effects of the size of WC grains on the damage evolution of WC-Co junk mills.The finite element method(FEM) simulation results showed that the finegrain(FG)...The main purpose of the current study was to investigate the effects of the size of WC grains on the damage evolution of WC-Co junk mills.The finite element method(FEM) simulation results showed that the finegrain(FG) tool retained its cutting edges radii longer than the coarse-grain(CG) tool.This event leads to the larger wear rate in the CG tool.Moreover,FEM analysis indicated that through increasing the feeding rate,the wear rate and the cutting forces increased as well.The observation of worn tool surface revealed that the formation of micro-pits,micro-cracks,scratching grooves and broken WC grains was among the common signs of the damage for both CG and FG tools.However,it was found that the defects are more intensive in the CG tool.This can be due to the lower boundary strength and less WC connectivity in the CG milling tool.The finer grains also decreased the mean free path in the Co binder and impeded the micro-cracks propagation in the material.展开更多
文摘Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedicalfields.Recent advancements in modern powder metallurgy techniques,such as spark plasma technique(SPS),have enabled achieving near-net-shape products with tailored properties and decreased in-process oxidation.However,improving their mechanical and physical properties require further enhancement.In this study,a novel Mg-0.7Ca alloy was produced using SPS process.The effects of process parameters such as sintering time and additive type on the microstructural evolutions,phase arrangements,and mechanical and physical properties of the consolidated materials were investigated through various characterization techniques.Full-dense samples were produced from 60-minute ball-milled powder mixtures through spark plasma sintering at 420℃ for 7,10,and 13 min under 38 MPa of externally applied pressure.The obtained samples were then characterized using Field Emission Scanning Electron Microscopy(FESEM),Electron Backscatter Diffraction(EBSD),X-ray Energy Dispersive Spectroscopy(EDS),and X-ray Diffraction(XRD)analysis methods,as well as mechanical tests including compression strength and micro-hardness measurements.The results indicated that while improved densification behavior is observed in paraffin-contained samples,relatively better compression properties are achieved in starch-contained alloys.It is also found that the phase arrangement of the starch-contained samples includes higher fractions of the secondary phases such as oxides and residual carbons,which can positively affect the mechanical strength,despite decreased hardness.The microstructural characterizations showed an intensified thermomechanical response of the materials in both groups via increased sintering time.However,the competition between the influencing parameters causes scattered strengthening behavior and texture in the consolidated samples.Detailed discussions about the densification behavior,texture,and obtained characteristics were also included.
文摘The main purpose of the current study was to investigate the effects of the size of WC grains on the damage evolution of WC-Co junk mills.The finite element method(FEM) simulation results showed that the finegrain(FG) tool retained its cutting edges radii longer than the coarse-grain(CG) tool.This event leads to the larger wear rate in the CG tool.Moreover,FEM analysis indicated that through increasing the feeding rate,the wear rate and the cutting forces increased as well.The observation of worn tool surface revealed that the formation of micro-pits,micro-cracks,scratching grooves and broken WC grains was among the common signs of the damage for both CG and FG tools.However,it was found that the defects are more intensive in the CG tool.This can be due to the lower boundary strength and less WC connectivity in the CG milling tool.The finer grains also decreased the mean free path in the Co binder and impeded the micro-cracks propagation in the material.
