Near dense Mg 0.5 wt.% Zr（0,1,2.5 and 4） wt.% La alloys were successfully synthesized by disintegrated melt deposition technique followed by hot extrusion and were characterized for their microstructural, ignition, ...Near dense Mg 0.5 wt.% Zr（0,1,2.5 and 4） wt.% La alloys were successfully synthesized by disintegrated melt deposition technique followed by hot extrusion and were characterized for their microstructural, ignition, hardness, tensile and compression properties. Combined effects of Zr and La assisted in significant grain refinement of Mg and Mg 0.5 wt.% Zr 4 wt.% La exhibited an average grain size as low as ~2.75 μm. High ignition temperature of ~645 oC was realized with Mg 0.5 wt.% Zr（1,2.5 and 4） wt.% La alloys. Microhardness value as high as ~103 Hv was observed with Mg 0.5 wt.% Zr 4 wt.% La alloy. Under room temperature tensile and compression loading, significant improvements in the strength properties of pure Mg with the addition of 0.5 wt.% Zr（0, 1, 2.5 and 4） wt.% La was observed. Mg 0.5 wt.% Zr 4 wt.% La exhibited the maximum 0.2% tensile and compression yield strengths of ~283 MPa and ~264 MPa, respectively. The tensile and compression fracture strain values of synthesized pure Mg were found to be unaffected with the addition of 0.5 wt.% Zr. But the tensile fracture strain reduced with the addition of La while the compressive fracture strain was unaffected. Minimal tensile-compression asymmetry（~1） was exhibited by Mg 0.5 wt.% Zr（1 and 2.5） wt.% La alloys.展开更多
TheLa0.5Pr0.2Zr0.1Mg0.2Ni2.75Co0.45Fe0.1Al0.2（M0 and Zr0.65Ti0.35（Mn0.2V0.2Cr0.15Ni0.45）l.76 （M2） hydrogen storage alloys were prepared by inductive melting. In addition, the M1＋30 wt.%M2 composites were success...TheLa0.5Pr0.2Zr0.1Mg0.2Ni2.75Co0.45Fe0.1Al0.2（M0 and Zr0.65Ti0.35（Mn0.2V0.2Cr0.15Ni0.45）l.76 （M2） hydrogen storage alloys were prepared by inductive melting. In addition, the M1＋30 wt.%M2 composites were successively prepared by using high-energy ball milling technology. From the X-ray diffraction （XRD） analysis, it was found that M1 and M2 alloys still retained their respective main phases in the MI＋30 wt.%M2 composites. The scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） indicated that the decrease in discharge capacity of MI and M2 alloy electrodes was ascribed to the oxidation-dissolution of La, Pr, Mg and Ti, Mn, V, Cr active elements, respectively. The electrochemical studies showed that the M1＋30 wt.%M2 composite electrode ball milling for 5 rain exhibited excellence cyclic stability （92.3%） after 80 charge/discharge cycles, which was higher than 77.7 % and 85.6% of MI and M2 alloy electrodes, respectively. Moreover, at the discharge current density of 1200 mA/g, the high rate dis- charge ability （HRD） of the M1＋30 wt.%M2 composite electrode increased from 61.5% （5 rain） to 70.3% （10 rain）. According to the linear polarization, Tafel polarization and cyclic voltammograms （CV）, the electrochemical kinetics of hydrogen reaction on the sur- face of the electrode and hydrogen diffusion rate in the bulk of alloy were also improved in the ML＋30 wt.%M2composite with in- creasing ball milling time.展开更多
基金Project supported by Singapore Ministry of Education Academic Research Fund Tier 2(R265000498112)
文摘Near dense Mg 0.5 wt.% Zr（0,1,2.5 and 4） wt.% La alloys were successfully synthesized by disintegrated melt deposition technique followed by hot extrusion and were characterized for their microstructural, ignition, hardness, tensile and compression properties. Combined effects of Zr and La assisted in significant grain refinement of Mg and Mg 0.5 wt.% Zr 4 wt.% La exhibited an average grain size as low as ~2.75 μm. High ignition temperature of ~645 oC was realized with Mg 0.5 wt.% Zr（1,2.5 and 4） wt.% La alloys. Microhardness value as high as ~103 Hv was observed with Mg 0.5 wt.% Zr 4 wt.% La alloy. Under room temperature tensile and compression loading, significant improvements in the strength properties of pure Mg with the addition of 0.5 wt.% Zr（0, 1, 2.5 and 4） wt.% La was observed. Mg 0.5 wt.% Zr 4 wt.% La exhibited the maximum 0.2% tensile and compression yield strengths of ~283 MPa and ~264 MPa, respectively. The tensile and compression fracture strain values of synthesized pure Mg were found to be unaffected with the addition of 0.5 wt.% Zr. But the tensile fracture strain reduced with the addition of La while the compressive fracture strain was unaffected. Minimal tensile-compression asymmetry（~1） was exhibited by Mg 0.5 wt.% Zr（1 and 2.5） wt.% La alloys.
基金supported by the Natural Science Foundation of Guangxi (2011GXNSFA018034)the Program for Characteristic Professionalism and Integrated Curriculum Construction in Colleges of Guangxi (GXTSZY024)
文摘TheLa0.5Pr0.2Zr0.1Mg0.2Ni2.75Co0.45Fe0.1Al0.2（M0 and Zr0.65Ti0.35（Mn0.2V0.2Cr0.15Ni0.45）l.76 （M2） hydrogen storage alloys were prepared by inductive melting. In addition, the M1＋30 wt.%M2 composites were successively prepared by using high-energy ball milling technology. From the X-ray diffraction （XRD） analysis, it was found that M1 and M2 alloys still retained their respective main phases in the MI＋30 wt.%M2 composites. The scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） indicated that the decrease in discharge capacity of MI and M2 alloy electrodes was ascribed to the oxidation-dissolution of La, Pr, Mg and Ti, Mn, V, Cr active elements, respectively. The electrochemical studies showed that the M1＋30 wt.%M2 composite electrode ball milling for 5 rain exhibited excellence cyclic stability （92.3%） after 80 charge/discharge cycles, which was higher than 77.7 % and 85.6% of MI and M2 alloy electrodes, respectively. Moreover, at the discharge current density of 1200 mA/g, the high rate dis- charge ability （HRD） of the M1＋30 wt.%M2 composite electrode increased from 61.5% （5 rain） to 70.3% （10 rain）. According to the linear polarization, Tafel polarization and cyclic voltammograms （CV）, the electrochemical kinetics of hydrogen reaction on the sur- face of the electrode and hydrogen diffusion rate in the bulk of alloy were also improved in the ML＋30 wt.%M2composite with in- creasing ball milling time.
