Solidification behaviors of Pt-containing 718Plus superalloys were studied by scanning electron microscopy(SEM),energy dispersive spectrum(EDS),differential scanning calorimetry(DSC)and simulation calculations.It is f...Solidification behaviors of Pt-containing 718Plus superalloys were studied by scanning electron microscopy(SEM),energy dispersive spectrum(EDS),differential scanning calorimetry(DSC)and simulation calculations.It is found that Pt increases solidification range and decreases solidus temperature of the alloy and precipitation temperature of Laves+ γ eutectic phase since Pt enlarges the region of γ phase by increasing Nb solubility.In addition,Pt segregates to the interdendritic region and increases the segregation of Nb and Ti in the interdendritic region due to the strong attractive interactions between Pt and Nb/Ti.As a result,Pt promotes the precipitation of the Laves+ γ eutectic phase andηphase around eutectic phase.The increase of solidification range and segregation degrees of Nb and Al caused by Pt also promotes the precipitation and growth of γ'+γ" phase around eutectic phase.These results provide experimental bases for understanding the mechanism of Pt in solidification behavior of superalloys.展开更多
The microstructures and textures of the non-oriented electrical steel sheets under various annealing conditions were investigated.The orientation gradient in the interior of grains appeared on the surface of steel she...The microstructures and textures of the non-oriented electrical steel sheets under various annealing conditions were investigated.The orientation gradient in the interior of grains appeared on the surface of steel sheets after α→γ→α transformation in various atmospheres.The orientation gradient that appeared on the surface was inherited into the center of the steel sheet in H2 atmosphere,while that appeared only in the grains of the surface layer during γ→α transformation with N2 atmosphere.The thin oxide scale was generated in various atmospheres containing traces of O2 and H2O.The formation mechanism of orientation gradient is related to the thermal stress caused by the difference of thermal expansion coefficients between the oxide scale and the thin ferrite on the surface.The combined effect of phase transformation stress and thermal stress caused the plastic deformation of the thin ferrite grains on the surface in the initial stage of γ→α transformation,and then the orientations of the thin ferrite grains gradually rotated and caused the orientation gradient in the interior of grains.展开更多
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.51771018,51871022)the Fundamental Research Funds for the Central Universities(Nos.FRF-GF-19-004B,FRF-GF-20-01A)。
文摘Solidification behaviors of Pt-containing 718Plus superalloys were studied by scanning electron microscopy(SEM),energy dispersive spectrum(EDS),differential scanning calorimetry(DSC)and simulation calculations.It is found that Pt increases solidification range and decreases solidus temperature of the alloy and precipitation temperature of Laves+ γ eutectic phase since Pt enlarges the region of γ phase by increasing Nb solubility.In addition,Pt segregates to the interdendritic region and increases the segregation of Nb and Ti in the interdendritic region due to the strong attractive interactions between Pt and Nb/Ti.As a result,Pt promotes the precipitation of the Laves+ γ eutectic phase andηphase around eutectic phase.The increase of solidification range and segregation degrees of Nb and Al caused by Pt also promotes the precipitation and growth of γ'+γ" phase around eutectic phase.These results provide experimental bases for understanding the mechanism of Pt in solidification behavior of superalloys.
基金This work is supported by the National Natural Science Foundation of China(No.51771024).
文摘The microstructures and textures of the non-oriented electrical steel sheets under various annealing conditions were investigated.The orientation gradient in the interior of grains appeared on the surface of steel sheets after α→γ→α transformation in various atmospheres.The orientation gradient that appeared on the surface was inherited into the center of the steel sheet in H2 atmosphere,while that appeared only in the grains of the surface layer during γ→α transformation with N2 atmosphere.The thin oxide scale was generated in various atmospheres containing traces of O2 and H2O.The formation mechanism of orientation gradient is related to the thermal stress caused by the difference of thermal expansion coefficients between the oxide scale and the thin ferrite on the surface.The combined effect of phase transformation stress and thermal stress caused the plastic deformation of the thin ferrite grains on the surface in the initial stage of γ→α transformation,and then the orientations of the thin ferrite grains gradually rotated and caused the orientation gradient in the interior of grains.
