This paper presents a versatile method for synthesizing electron-rich polynuclear transition metal clusters with chalcogen bridges and phosphine ligands.The reactions of transition metal complexes(R3P)2MX2(M=Co,Ni;R=P...This paper presents a versatile method for synthesizing electron-rich polynuclear transition metal clusters with chalcogen bridges and phosphine ligands.The reactions of transition metal complexes(R3P)2MX2(M=Co,Ni;R=Ph,Bu,Et;X=Cl,Br) with bridging reagents Na2Ex (E=S,Se;x=1.2) are described.The geometric and electronic structures of a series of polynuclear transition metal clusters with trianglar M3 units are also discussed.展开更多
The formation of borides M_3B_2 M_2B_2 and M_(23)B_6 may be carried out from the melt-quenched Fe_(70)Cr_(18)Mo_2SiB_9 during 700—1150℃ annealing.As the temperature raising,the M_2B,the majority being Fe_2B.may be g...The formation of borides M_3B_2 M_2B_2 and M_(23)B_6 may be carried out from the melt-quenched Fe_(70)Cr_(18)Mo_2SiB_9 during 700—1150℃ annealing.As the temperature raising,the M_2B,the majority being Fe_2B.may be gradually replaced by Cr_2B via the co-existence between Fe_2B and Cr_2B.The Cr_2B may be formed by trans formation of Fe_2B through the atomic substitu- tion and structural adjustment.The thin slice of remaining Fe_2B is sandwiched between(100) faces of(Cr,Fe)_2B as stacking fault.The M_2B_2 is virtually composed of the Mo_(1+x)(Fe,Cr)_(2-x)B_2 where x(0≤x≤1)increases with the increase of temperature.展开更多
Thermo-Calc software package (TCP+DICTRA) was used to simulate the carbide transformation process in die steel for plastic. Combined with TEM analysis, the calculated result confirms that the carbide in equilibrium st...Thermo-Calc software package (TCP+DICTRA) was used to simulate the carbide transformation process in die steel for plastic. Combined with TEM analysis, the calculated result confirms that the carbide in equilibrium state is M_7C_3 carbide. The dissolution of M_7C_3 carbide in steel is predicted by DICTRA program. It was shown that the temperature remarkably affects the dissolution process of M_7C_3 carbide, but the influence of alloy elements such as manganese and molybdenum can be neglected in this steel.展开更多
The micro structure of 10Cr15MoVCo electroslag remelting(ESR)ingot was observed using an optical microscope and a scanning electron microscope.There are differences in the number,size,and distribution of primary carbi...The micro structure of 10Cr15MoVCo electroslag remelting(ESR)ingot was observed using an optical microscope and a scanning electron microscope.There are differences in the number,size,and distribution of primary carbides in different positions of ESR ingot.The results show that the two-dimensional morphology of primary carbides is blocky,fibrous,and spherulitic.The three-dimensional morphology of primary carbides is blocky,spherulitic,fibrous,and short rods.X-ray diffraction results show that primary carbides are M_(7)C_(3) carbides.Electron backscattered diffraction results indicate that large-sized primary carbides consist of blocky,fibrous,and spherulitic carbides with different orientations.High-tem-perature diffusion annealing experiments show that as the temperature increases,the continuity between primary carbides decreases,and the precipitated secondary carbides disappear.The area fraction of primary carbides is reduced,but the morphology of primary carbide is unchanged.The effect of high-temperature diffusion annealing on the dissolution of M_(7)C_(3) primary carbon compounds in ESR ingot was limited.展开更多
文摘This paper presents a versatile method for synthesizing electron-rich polynuclear transition metal clusters with chalcogen bridges and phosphine ligands.The reactions of transition metal complexes(R3P)2MX2(M=Co,Ni;R=Ph,Bu,Et;X=Cl,Br) with bridging reagents Na2Ex (E=S,Se;x=1.2) are described.The geometric and electronic structures of a series of polynuclear transition metal clusters with trianglar M3 units are also discussed.
文摘The formation of borides M_3B_2 M_2B_2 and M_(23)B_6 may be carried out from the melt-quenched Fe_(70)Cr_(18)Mo_2SiB_9 during 700—1150℃ annealing.As the temperature raising,the M_2B,the majority being Fe_2B.may be gradually replaced by Cr_2B via the co-existence between Fe_2B and Cr_2B.The Cr_2B may be formed by trans formation of Fe_2B through the atomic substitu- tion and structural adjustment.The thin slice of remaining Fe_2B is sandwiched between(100) faces of(Cr,Fe)_2B as stacking fault.The M_2B_2 is virtually composed of the Mo_(1+x)(Fe,Cr)_(2-x)B_2 where x(0≤x≤1)increases with the increase of temperature.
文摘Thermo-Calc software package (TCP+DICTRA) was used to simulate the carbide transformation process in die steel for plastic. Combined with TEM analysis, the calculated result confirms that the carbide in equilibrium state is M_7C_3 carbide. The dissolution of M_7C_3 carbide in steel is predicted by DICTRA program. It was shown that the temperature remarkably affects the dissolution process of M_7C_3 carbide, but the influence of alloy elements such as manganese and molybdenum can be neglected in this steel.
基金This work was supported by the Guangdong YangFan Innovative&Entrepreneurial Research Team Program(No.2016YT03C071)the Guangdong Science and Technology Special Fund Project(No.SDZX202005)the National Natural Science Foundation of China(Nos.51874030 and 51904022).
文摘The micro structure of 10Cr15MoVCo electroslag remelting(ESR)ingot was observed using an optical microscope and a scanning electron microscope.There are differences in the number,size,and distribution of primary carbides in different positions of ESR ingot.The results show that the two-dimensional morphology of primary carbides is blocky,fibrous,and spherulitic.The three-dimensional morphology of primary carbides is blocky,spherulitic,fibrous,and short rods.X-ray diffraction results show that primary carbides are M_(7)C_(3) carbides.Electron backscattered diffraction results indicate that large-sized primary carbides consist of blocky,fibrous,and spherulitic carbides with different orientations.High-tem-perature diffusion annealing experiments show that as the temperature increases,the continuity between primary carbides decreases,and the precipitated secondary carbides disappear.The area fraction of primary carbides is reduced,but the morphology of primary carbide is unchanged.The effect of high-temperature diffusion annealing on the dissolution of M_(7)C_(3) primary carbon compounds in ESR ingot was limited.
