TiC based steel bonded carbides with the addition of nano TiN were prepared by vacuum sintering techniques.The microstructure was investigated using scanning electron microscopy（SEM） and transmission electron micros...TiC based steel bonded carbides with the addition of nano TiN were prepared by vacuum sintering techniques.The microstructure was investigated using scanning electron microscopy（SEM） and transmission electron microscopy（TEM）,and the mechanical properties,such as bending strength,impact toughness,hardness,and density,were measured.The results indicate that the grain size becomes small and there is uniformity in the steel bonded carbide with nano addition;several smaller carbide particles are also found to be inlaid in the rim of the larger carbide grains and prevent the coalescence of TiC grains.The smaller and larger carbide grains joint firmly,and then the reduction of the average size of the grains leads to the increase in the mechanical properties of the steel bonded carbides with nano addition.But the mechanical properties do not increase monotonously with an increase in nano addition.When the nano TiN addition accounts for 6-8 wt.% of the amount of steel bonded carbides,the mechanical properties reach the maximum values and then decrease with further increase in nano TiN addition.展开更多
TiC/Crl8Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of ...TiC/Crl8Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope （SEM）, X-ray diffraction （XRD） and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm. With the increase of sintering temperature, the porosity of TiC/Crl8Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC particles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0. 9 are higher than those with C/Ti atomic ratio 1.0. The TiC particles with C/Ti atomic ratio 0. 9 are much finer and more homogeneous.展开更多
The majority of Ti is found to be preferentially precipitated in the form of TiC from medium manganese steel melt.The TiC may contribute to the heterogeneous nuclei of fine austenite crystallization,to the retardation...The majority of Ti is found to be preferentially precipitated in the form of TiC from medium manganese steel melt.The TiC may contribute to the heterogeneous nuclei of fine austenite crystallization,to the retardation of dislocation movement as well as to pile-up and proliferate the dislocations,thus,the matrix of the as-cast steel will be effectively strength- ened.It was also found that the TiC can be acted as the heterogeneous nuclei of the nodular eutectic carbide formation and caused the dispersion o fan abundance of the carbide in the interstices between austenite dendrite arms.展开更多
文摘TiC based steel bonded carbides with the addition of nano TiN were prepared by vacuum sintering techniques.The microstructure was investigated using scanning electron microscopy（SEM） and transmission electron microscopy（TEM）,and the mechanical properties,such as bending strength,impact toughness,hardness,and density,were measured.The results indicate that the grain size becomes small and there is uniformity in the steel bonded carbide with nano addition;several smaller carbide particles are also found to be inlaid in the rim of the larger carbide grains and prevent the coalescence of TiC grains.The smaller and larger carbide grains joint firmly,and then the reduction of the average size of the grains leads to the increase in the mechanical properties of the steel bonded carbides with nano addition.But the mechanical properties do not increase monotonously with an increase in nano addition.When the nano TiN addition accounts for 6-8 wt.% of the amount of steel bonded carbides,the mechanical properties reach the maximum values and then decrease with further increase in nano TiN addition.
文摘TiC/Crl8Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope （SEM）, X-ray diffraction （XRD） and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm. With the increase of sintering temperature, the porosity of TiC/Crl8Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC particles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0. 9 are higher than those with C/Ti atomic ratio 1.0. The TiC particles with C/Ti atomic ratio 0. 9 are much finer and more homogeneous.
文摘The majority of Ti is found to be preferentially precipitated in the form of TiC from medium manganese steel melt.The TiC may contribute to the heterogeneous nuclei of fine austenite crystallization,to the retardation of dislocation movement as well as to pile-up and proliferate the dislocations,thus,the matrix of the as-cast steel will be effectively strength- ened.It was also found that the TiC can be acted as the heterogeneous nuclei of the nodular eutectic carbide formation and caused the dispersion o fan abundance of the carbide in the interstices between austenite dendrite arms.
