Recrystallization of Ni_3 Al Base Single Crystal Alloy IC6SX with Different Surface Mechanical Processes

The recrystallization behavior of Ni 3 Al base single crystal alloy IC6SX with different mechanical processes has been studied.The specimens of the alloy were treated by surface cleaning and cold working during the blades manufacture,and then heat treated in the temperature range of 800-1260℃ for 1 h to 4 h.The microstrcture of the specimens were examined by optical and scaning electron microscopy,and the room temperature tensile property,stress rupture property under the test condition of 1100℃/130 MPa,and the thermal cycle fatigue resistance under 1100-20℃ of the specimens with and without recrystallization were carried out.The experimental results showed that the initial recrystallization nucleation temperatures of the alloy by dry grit blasting,wet grit blasting,indentation,shot blasting and burnishing were 900-950℃/1 h,1000-1100℃/1 h,1200-1220℃/4 h,1220-1240℃/1 h and 1220-1240 C/1 h,respectively and the primal recrystallization completing temperatures of the alloy by those mechanical processes mentioned above were 1200-1210℃/1 h,1100-1200℃/1 h,1220-1240℃/4 h,1240-1260℃/1 h and 1240-1260℃/1 h,respectively.The results also indicated that the deformation amount of the specimens by burnishing and dry grit blasting was bigger than that by wet grit blasting and shot blasting according to their recrystallization temperature and the microhardness profile below the surface of specimens.It has been found that the recrystallization had no evident effect on mechanical properties of the alloy.

Microstructural Stability of a Single Crystal Superalloy DD8 during Thermal Exposure

Microstructural stability of a nickel base single crystal alloy DD8 has been investigated.Standard heat treated specimen showed good microstructural stability at 950℃.While under the as-cast condition,a kind of rod-like phase precipitated in the interdendritic region of as-cast specimen during thermal exposure.The phase,which has bcc structure,was enriched with Cr.Thermo-calc also predicted precipitation of a bcc phase at around 950℃.The Cr-rich bcc phase was considered asα-Cr and formed due to the segregation of Cr under the as-cast condition.

Preparation and tensile properties of DD5 single crystal castings

The preparation procedure of DD5 single crystal castings was optimized. The microstructure characteristics of DD5 single crystal superalloy were investigated by microstructure observation and segregation behavior examination. The results show that the grain orientation is optimized by constraining the spiral crystallizer in [001] orientation and spatial scale. Also, the γ＇ phase of inter-dendrites is larger and more irregular than that in dendrite arms. High temperature tensile tests of DD5 single crystal castings exhibit that the peak stress increases with increasing temperature, while the area reduction shows an opposite trend, when the temperature is below 800℃; meanwhile, when the temperature is between 800℃ and 1000℃, the fracture stress of the alloy is the same as the peak stress. The fracture mode changes from shear to ductile with increasing temperature from 600℃ and 1000℃.

Modeling and Identification of Anisotropic Damping Property of Ni-Based Alloys by FEM-Simulation

The modeling and identification of anisotropic damping property of Ni based single crystal alloys are presented. The anisotropic material damping property is modeled by 3 D rheological equations and identified by using specimen modal damping ratios and FEM simulation. The measured damping ratios which exhibit strong anisotropy are predicted better by the method presented than by other methods.

Formation and capturing of nanoparticles in Cu-1wt.%Fe alloy melt during directional solidification process

A single crystal Cu-1wt.%Fe alloy with finely dispersed iron-rich nanoparticles which keep coherent interface with the copper matrix was prepared under directional solidification.Formation of nanoparticles in the alloy melt was investigated by performing differential scanning calorimeter tests and designed water quenching experiment at a certain temperature.Results show that iron-rich nanoparticles are formed in the Cu-1wt.%Fe alloy melt before primaryα-Cu forms,which is not consistent with equilibrium phase diagram.Mechanism that iron-rich nanoparticles are uniformly captured in the matrix was described,which is that numerous nanoparticles follow Brownian motions and are engulfed in the solidified matrix which makes it possible to form uniformly distributed nanoparticles reinforced single crystal Cu-1wt.%Fe alloy.