Three-dimensional simulation of inhomogeneous tertiary creep in single-crystal superalloy testpieces

2000 ◽  
Vol 43 (8) ◽  
pp. 719-725 ◽  
Author(s):  
M.A Rist ◽  
A.S Oddy ◽  
R.C Reed
2011 ◽  
Vol 284-286 ◽  
pp. 1584-1587
Author(s):  
Zhen Xue Shi ◽  
Jia Rong Li ◽  
Shi Zhong Liu ◽  
Jin Qian Zhao

The specimens of low angle boundaries were machined from the second generation single crystal superalloy DD6 blades. The microstructures of low angle boundaries (LAB) were investigated from three scales of dendrite, γ′ phase and atom with optical microscopy (OM), scanning electron microscope (SEM), transition electron microscope (TEM) and high resolution transmission electrion microscopy (HREM). The results showed that on the dendrite scale LAB is interdendrite district formed by three dimensional curved face between the adjacent dendrites. On the γ′ phase scale LAB is composed by a thin layer γ phase and its bilateral imperfect cube γ′ phase. On the atom scale LAB is made up of dislocations within several atom thickness.


2008 ◽  
Vol 12 (4) ◽  
pp. 275-289 ◽  
Author(s):  
Alexander Staroselsky ◽  
Brice Cassenti

2007 ◽  
Vol 359-360 ◽  
pp. 6-10 ◽  
Author(s):  
Jia Xuan Chen ◽  
Ying Chun Liang ◽  
Qing Shun Bai ◽  
Yu Lan Tang ◽  
Ming Jun Chen

Molecular dynamics (MD) simulations of nanometric scratching with diamond tip are conducted on single crystal copper crystal plane (010), and MD simulations are carried out to investigate the mechanism of material removal and the generation of defects on the surface, subsurface and inner of material. During the process of diamond tip scratching the surface of single crystal copper on conditions of different scratching speeds, depths and widths. We achieved the forming details of the chip. While the generation and moving process of defects, such as dislocation, are recorded. The different times of atomic displacement and interaction force are also shown through MD simulation. The evolvement of the lattice pattern in the abrasive processes are analysed by radial distribution function (RDF) and computing the changes of workpiece’s atomic displaces and forces. At the same time, the lattice reconfiguration and the onset and the evolvement process of defects and are analysed by RDF and atomic perspective method, respectively. The simulation results show that scratching speed play role in the course of the form of removing chips, and that different scratching widths and depths of tool have effect on onset and evolvement of lattice defects of workpiece in abrasive processes. This study can give more fundamental understanding of nanosconstruction from atomistic motions and contribute to the design, manufacture and manipulation of nano-devices


2014 ◽  
Vol 783-786 ◽  
pp. 2148-2153
Author(s):  
Hai Peng Jin ◽  
Jia Rong Li

Competitive growth and grain selection were simulated and analyzed during the directional solidification with the conditions for single crystal superalloy DD6 castings using Commercial software, ProCAST. A three dimensional cellular automaton (CA) model coupled with finite-element (FE) heat flow calculation was applied. Measurements at the grain scale were made using the EBSD method at the cross sections in the starter block and grain selector at an interval of 4 mm from the chill surface. The grain characteristics and the rules of competition growth were obtained. The validity of the simulation results were compared with those of the experiment. It concluded that the model-predicted tendency shows satisfactory agreement with the experiment. Increasing the distance from the chill decreases the number of grains, increases the radius of grains and drives the crystallization orientation of grains to principal stress orientation.


2012 ◽  
Vol 535-537 ◽  
pp. 888-893
Author(s):  
Jian Yu ◽  
Jia Rong Li ◽  
Zhen Xue Shi ◽  
Jin Qian Zhao ◽  
Shi Zhong Liu ◽  
...  

The creep and microstructures of DD6 single crystal superalloy with [001] orientation at 760°C and 785MPa were investigated. The results show that large a/2 dislocations are spread and concentrated in matrix channels during incubation period, and few of stacking faults are observed at later stage of incubation period. The stage of primary creep is characterized by the stacking faults shearing γ' phases, and the density of a/2 dislocations in the matrix continues to increase. The density of the stacking faults increases during the stages of secondary and tertiary creep.


2010 ◽  
Vol 654-656 ◽  
pp. 1482-1485
Author(s):  
Dong Pan ◽  
Qing Yan Xu ◽  
Bai Cheng Liu

Ni3Al based superalloy has recently been used for the single crystal gas turbine blade. The grain selection behavior in grain selector directly determines the casting’s final microstructure and properties. A mathematical model based on the modified CA-FD method was developed for the three-dimensional simulation of directional solidification process of Ni3Al based single crystal superalloy castings. The microstructure evolution was simulated with the modified Cellular Automaton method. The grain selection process in the grain selector and final microstructure of casting were simulated. The results indicate that the stray grain is easy to nucleate at the middle part of the pigtail because of the discontinuous mushy zones formation. This agrees with previous published experimental results. Based on simulated results, a newly designed grain selector with optimized geometry was proposed to avoid stray grains.


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