The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions （SRORs） in the met...The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions （SRORs） in the metallic glass though it is identified to be amorphous by X-ray diffraction method. Furthermore, the amorphous degree shows a close correlation with the microstructure of corresponding mother ingot. The crystallization kinetics was investigated by differential scanning calorimetry under isochronal and isothermal conditions. The results show that the crystallization is triggered by the growth of the pre-existing SRORs and the growth is three-dimension diffusion-controlled. The amorphous degree of Zr60Al15Ni25 bulk metallic glass considerably influences its crystallization kinetics, namely, the more homogeneous distribution of atoms results in a more sluggish nucleation behavior.展开更多
The microstructures and corrosion behaviors of as-cast,T4-treated,and T6-treated Mg-6Gd-3Y-0.5Zr alloys were systematically investigated by SEM,TEM,immersion test,and electrochemical corrosion test.The results show th...The microstructures and corrosion behaviors of as-cast,T4-treated,and T6-treated Mg-6Gd-3Y-0.5Zr alloys were systematically investigated by SEM,TEM,immersion test,and electrochemical corrosion test.The results show that the microstructure of the as-cast alloy is composed ofα-Mg and Mg_(24)(Gd,Y)_(5) eutectic phase,and in T4-treated alloy,Mg_(24)(Gd,Y)_(5) phase dissolves into theα-Mg matrix,leading to an increase in the(Y,Gd)H_(2) phase.After T6 treatment,nanoscale Mg_(24)(Gd,Y)_(5) phase dispersedly precipitates from theα-Mg matrix,and exhibits a specific orientation relationship with the α-Mg:(332)Mg_((24)(Gd,Y)_(5))//(1011)_(α-Mg),[136]Mg_((24)(Gd,Y)_(5))//[1210]_(α-Mg).The corrosion resistance of the Mg-6Gd-3Y-0.5Zr alloys can be ranked in the following order:T6-treated alloy exhibits the highest corrosion resistance,followed by the T4-treated alloy,and finally,the as-cast alloy.The corrosion products of the alloys are all composed of MgO,Mg(OH)_(2),Gd_(2)O_(3),Y_(2)O_(3),and MgCl_(2).The corrosion behavior of Mg-6Gd-3Y-0.5Zr alloy is closely related to the precipitated phase.By establishing the relationship between corrosion rate,hydrogen evolution rate,and corrosion potential,it is further demonstrated that during the micro galvanic corrosion process,the coarse Mg_(24)(Gd,Y)_(5)phase in the as-cast alloy undergoes extensive dissolution,and(Y,Gd)H_(2) phase promotes the dissolution of theα-Mg matrix in the T4-treated alloy,intensifying the hydrogen evolution reaction.The T6-treated alloy,with dispersive precipitation of nanoscale Mg_(24)(Gd,Y)_(5) phase,exhibits better corrosion resistance performance.展开更多
The [Zr6(μ2-Cl)12Cl6H4]3- ion with C4v Symmetry in the title compounds has been calculated by DV-Xα program. The calculated results show that ther is almost no available covalence bonding between zirconium ato...The [Zr6(μ2-Cl)12Cl6H4]3- ion with C4v Symmetry in the title compounds has been calculated by DV-Xα program. The calculated results show that ther is almost no available covalence bonding between zirconium atoms and significant Zr 4d AO compositions in the MOs. but there are much stronger Zr-Cl(bridging) bonding. All analysis results suggest that these compounds would be the cluster with Zr6Cl12 cage linked by Zr-Cl bridging bonding plus six Cl teminal ligands rather than the hexazirconium cluster in view of the chemical bonding.展开更多
The mechanical properties, microstructure and tensile fracture of Ti-6.5AI-IMo-IV-2Zr large section bars produced by three diffrent forging processes were investigated. The results show that when billet forging and fi...The mechanical properties, microstructure and tensile fracture of Ti-6.5AI-IMo-IV-2Zr large section bars produced by three diffrent forging processes were investigated. The results show that when billet forging and finish forging were conducted by means of fullering at high and low temperature of r-region, respectively; the microstructure of forged bar is coarse Widmanstaten structure; the mechanical properties, especially the reduction of cross-sectional area, are poor, and the room temperature tensile fracture presents a brittle feature. While billet forging was carried out by upset-fullering at high temperature of the r-region, and finish forging was proceeded through fullering at （a＋fl）-region, the microstructure of forged bar was a duplex structure, the bar has better comprehensive mechanical properties, and the room temperature tensile fracture reveals a ductile feature. In order to obtain qualified Ti-6.SAI-IMo-IV-2Zr alloy bar, it is the key that as-cast microstructure should be completely broken during billet forging, and the forging temperature and deformation are also well controlled upon finishing forging.展开更多
基金Project (50804032) supported by the National Natural Science Foundation of ChinaProject (2008011046) supported by the Natural Science Foundation of Shanxi Province, ChinaProject (20080321036) supported by the Key Technologies R & D Program of Shanxi Province, China
文摘The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions （SRORs） in the metallic glass though it is identified to be amorphous by X-ray diffraction method. Furthermore, the amorphous degree shows a close correlation with the microstructure of corresponding mother ingot. The crystallization kinetics was investigated by differential scanning calorimetry under isochronal and isothermal conditions. The results show that the crystallization is triggered by the growth of the pre-existing SRORs and the growth is three-dimension diffusion-controlled. The amorphous degree of Zr60Al15Ni25 bulk metallic glass considerably influences its crystallization kinetics, namely, the more homogeneous distribution of atoms results in a more sluggish nucleation behavior.
基金supported by the Key Project of Equipment Pre-research Field Fund under Grant No.61409230407.
文摘The microstructures and corrosion behaviors of as-cast,T4-treated,and T6-treated Mg-6Gd-3Y-0.5Zr alloys were systematically investigated by SEM,TEM,immersion test,and electrochemical corrosion test.The results show that the microstructure of the as-cast alloy is composed ofα-Mg and Mg_(24)(Gd,Y)_(5) eutectic phase,and in T4-treated alloy,Mg_(24)(Gd,Y)_(5) phase dissolves into theα-Mg matrix,leading to an increase in the(Y,Gd)H_(2) phase.After T6 treatment,nanoscale Mg_(24)(Gd,Y)_(5) phase dispersedly precipitates from theα-Mg matrix,and exhibits a specific orientation relationship with the α-Mg:(332)Mg_((24)(Gd,Y)_(5))//(1011)_(α-Mg),[136]Mg_((24)(Gd,Y)_(5))//[1210]_(α-Mg).The corrosion resistance of the Mg-6Gd-3Y-0.5Zr alloys can be ranked in the following order:T6-treated alloy exhibits the highest corrosion resistance,followed by the T4-treated alloy,and finally,the as-cast alloy.The corrosion products of the alloys are all composed of MgO,Mg(OH)_(2),Gd_(2)O_(3),Y_(2)O_(3),and MgCl_(2).The corrosion behavior of Mg-6Gd-3Y-0.5Zr alloy is closely related to the precipitated phase.By establishing the relationship between corrosion rate,hydrogen evolution rate,and corrosion potential,it is further demonstrated that during the micro galvanic corrosion process,the coarse Mg_(24)(Gd,Y)_(5)phase in the as-cast alloy undergoes extensive dissolution,and(Y,Gd)H_(2) phase promotes the dissolution of theα-Mg matrix in the T4-treated alloy,intensifying the hydrogen evolution reaction.The T6-treated alloy,with dispersive precipitation of nanoscale Mg_(24)(Gd,Y)_(5) phase,exhibits better corrosion resistance performance.
文摘The [Zr6(μ2-Cl)12Cl6H4]3- ion with C4v Symmetry in the title compounds has been calculated by DV-Xα program. The calculated results show that ther is almost no available covalence bonding between zirconium atoms and significant Zr 4d AO compositions in the MOs. but there are much stronger Zr-Cl(bridging) bonding. All analysis results suggest that these compounds would be the cluster with Zr6Cl12 cage linked by Zr-Cl bridging bonding plus six Cl teminal ligands rather than the hexazirconium cluster in view of the chemical bonding.
文摘The mechanical properties, microstructure and tensile fracture of Ti-6.5AI-IMo-IV-2Zr large section bars produced by three diffrent forging processes were investigated. The results show that when billet forging and finish forging were conducted by means of fullering at high and low temperature of r-region, respectively; the microstructure of forged bar is coarse Widmanstaten structure; the mechanical properties, especially the reduction of cross-sectional area, are poor, and the room temperature tensile fracture presents a brittle feature. While billet forging was carried out by upset-fullering at high temperature of the r-region, and finish forging was proceeded through fullering at （a＋fl）-region, the microstructure of forged bar was a duplex structure, the bar has better comprehensive mechanical properties, and the room temperature tensile fracture reveals a ductile feature. In order to obtain qualified Ti-6.SAI-IMo-IV-2Zr alloy bar, it is the key that as-cast microstructure should be completely broken during billet forging, and the forging temperature and deformation are also well controlled upon finishing forging.
