Microstructure Evolution in Undercooled Ni-Si Melt

2013 ◽  
Vol 749 ◽  
pp. 349-355
Author(s):  
Kai Fan ◽  
Feng Liu ◽  
Bao Quan Fu ◽  
Wen Zhong Luo ◽  
Yao He Zhou
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Solid Solubility ◽  
Molten Glass ◽  
Dendrite Fragmentation ◽  
Equilibrium Solidification ◽  
Good Agreement ◽  
Non Equilibrium

Upon non-equilibrium solidification, the intrinsic parameters, such as moving velocity, temperature, solute partition coefficient, and liquid and solid concentrations at the interface, deviate from their equilibrium characteristics, and the morphology of the as-solidified structure and the grain size are influenced by the non-equilibrium liqulid/solid transformation, which further influences the subquent solidstate transformation. Adopting molten glass purification technology combined with cycle superheating method, the microstructure evolution of Ni-11at.%Si alloy in different undercooling was investigated. It was found that, with the increase of the initial undercooling, grain refinement occurred in microstructures of undercooled Ni-11at.%Si alloy. Meanwhile, the NL model was used to discuss the two different dendrite morphologies. According to Karmas model for dendrite fragmentation, the grain refinement of undercooled Ni-11at.%Si alloy was in good agreement with the experimental data, and the grain size was reduced with the increasing ΔT. The energy-dispersive spectroscopy (EDS) measurement was applied to analyze the solid solubility of Si atom in α-Ni matrix. It was found that the solid solubility of Si atom in α-Ni matrix increased with undercooling. At the undercooling of T>220K , a complete solute trapping occurred.

Study on Microstructure Evolution in GH4169 Alloy Blade during Finish Forging

2012 ◽  
Vol 217-219 ◽  
pp. 1671-1675 ◽  
Author(s):  
Guang Xia Qi ◽  
Rui Bin Mei ◽  
Na Cao
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Grain Size ◽  
Dynamic Recrystallization ◽  
Microstructure Evolution ◽  
Prediction Error ◽  
Compression Tests ◽  
Deform 3D ◽  
Gh4169 Alloy ◽  
Good Agreement

Constitutive equations and dynamic recrystallization (DRX) model of GH4169 alloy were investigated using compression tests with temperature 940(°C)-1060(°C) and strain rate 0.001(s-1)-0.1(s-1). A coupled numerical simulation between thermal-mechanical and microstructure evolution was realized through embedding the developed user subroutines into the FEM software DEFORM-3D system. The simulated results show that higher speed of upper die is useful to the DRX but much higher and lower speed of upper die go against improving the finer and uniform of grain size in the blade. Furthermore, the grains are finer and uniform in the blade body compared with those of blade rabbet and damper platform. The experimental results of microstructure under the same forging condition were studied and the average grain degrees in the blade are over 9. The calculated results of microstructure have a good agreement with the measured value from experimental data and the prediction error is less than 7.0%. Therefore, the DRX model and developed program is reliable to optimize and improve the parameters in the blade finish forging.

Thermodynamic Modeling of the Mg-Ni-La-Cu System

2011 ◽  
Vol 314-316 ◽  
pp. 1262-1267 ◽  
Author(s):  
Xue Hui An ◽  
Qian Li ◽  
Jie Yu Zhang
Keyword(s):  
Experimental Data ◽  
Isothermal Section ◽  
Ternary System ◽  
Hydrogen Storage ◽  
Vertical Section ◽  
Solidification Path ◽  
Hydrogen Storage Alloys ◽  
Equilibrium Solidification ◽  
Good Agreement ◽  
Phase Relationships

The isothermal section at 573 K of the Ni-Cu-La system was experimentally validated as well as the Mg-La-Cu system was thermodynamically evaluated. Four sample alloys in the Ni-Cu-La system were prepared and analyzed by ICP, XRD and BSE/EDS. All the experimental results were compared favorably with the calculated phase relationships. For the Mg-La-Cu ternary system, the isothermal section at 673 K was assessed on the basis of the available results in literatures, which showed a good agreement with the experimental data. Based on the thermodynamic models and parameters of the six binaries and four ternaries, the Mg-Ni-La-Cu system was finally modeled. The non-equilibrium solidification path La0.7Mg0.3Ni2.8-xCux (x=0-0.4) and the vertical section of LaNi5-Mg2Cu were calculated and analyzed from the viewpoint of hydrogen storage alloys design.

Grain Flow for Rough Surfaces Considering Grain/Grain Collision Elasticity

2005 ◽  
Vol 127 (4) ◽  
pp. 837-844 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Hung-Jung Tsai
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Energy Loss ◽  
Collision Energy ◽  
Surface Characteristics ◽  
Roughness Effects ◽  
Lubrication Equation ◽  
Grain Flow ◽  
Mathematical Formulas ◽  
Good Agreement

Previous work by this group on an average lubrication equation for grain flow with roughness effects is extended to include grain-grain collision elasticity ranging from perfectly elastic to perfectly inelastic. The average lubrication equation is based on Haff’s grain flow theory, with flow factors from Patir and Cheng and Tripp’s use of perturbation. The derived flow factors are obtained as functions of rough surface characteristics, grain size, and collision pattern. As collision energy loss approaches zero, the inelastic results approach those for perfectly elastic grain collision. The mathematical formulas for flow factors, grain/grain collision elasticity, grain size, and roughness are presented and discussed. Predicitons for the elastic and inelastic cases are graphically demonstrated and compared. The derived average lubrication equation for grain flow shows good agreement with the theoretical and experimental data of Yu, Craig, and Tichy [J. Rheol., 38(4), 921 (1994)].

scholarly journals Microstructure Development in Additive Friction Stir-Deposited Cu

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1538
Author(s):  
Jonathan L. Priedeman ◽  
Brandon J. Phillips ◽  
Jessica J. Lopez ◽  
Brett E. Tucker Roper ◽  
B. Chad Hornbuckle ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Vickers Hardness ◽  
Work Hardening ◽  
Surface Oxide ◽  
Microstructure Development ◽  
Friction Stir ◽  
Grain Sizes

This work details the additive friction stir-deposition (AFS-D) of copper and evaluation of its microstructure evolution and hardness. During deposition, a surface oxide is formed on the deposit exterior. A very fine porosity is formed at the substrate–deposit interface. The deposit (four layers of 1 mm nominal height) is otherwise fully dense. The grains appear to have recrystallized throughout the deposit with varying levels of refinement. The prevalence of twinning was found to be dependent upon the grain size, with larger local grain sizes having a higher number of twins. Vickers hardness measurements reveal that the deposit is softer than the starting feedstock. This result indicates that grain refinement and/or higher twin densities do not replace work hardening contributions to strengthen Cu processed by additive friction stir-deposition.

Grain Refinement in Constrained Groove Pressing of 7050 Aluminum Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 2823-2826 ◽  
Author(s):  
Xiao Lei Dong ◽  
Bing Yun ◽  
Zhi Hao Ma
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Regression Analysis ◽  
Aluminum Alloy ◽  
Grain Refinement ◽  
7050 Aluminum Alloy ◽  
Simulation Results ◽  
Refinement Effect

Constrained groove pressing is a simple and effective method of grain refinement. Using the experimental data obtained by regression analysis, this paper analyzes the simulation of the four pass constrained groove pressing deformation of 7050 aluminum alloy. The simulation results show that the grain size of the billet is refined significantly after four pass constrained groove pressing deformation and decreases from the original 90 μm to a minimum of 14.0 μm. With the increase of the number of deformation passes, refinement effect becomes weakened gradually, the grain size tends to stabilize and the organization is more uniform.

Effect of Grain Refinement on the Mechanical Behaviour of Ferritic Steels: Evolution of Isotropic Hardening and Kinematic Hardening

2008 ◽  
Vol 584-586 ◽  
pp. 605-609 ◽  
Author(s):  
Olivier Bouaziz ◽  
A. Aouafi ◽  
Sebastien Allain
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Grain Refinement ◽  
Mechanical Behaviour ◽  
Kinematic Hardening ◽  
Metallic Alloys ◽  
Isotropic Hardening ◽  
Ferritic Steels ◽  
Size Refinement ◽  
Fine Grain

New experimental data related to the grain size and the Bauschinger effects have been obtained for ferritic steels with grain size in the range of 3.5-22m. As the data show an increasing contribution of the kinematic hardening with grain size refinement, a new physical based model describing the isotropic hardening and the kinematic hardening is presented and validated with regard to the grain size. The consequences are discussed for fine grain metallic alloys.

Microstructure Evolution in Magnesium Alloy ZK60 during Cyclic Extrusion and Compression

2014 ◽  
Vol 1035 ◽  
pp. 259-262
Author(s):  
Fei Han ◽  
Hong Wei Liu ◽  
Gang Chen
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Microstructural Evolution ◽  
Microstructure Evolution ◽  
Extrusion Ratio ◽  
Technical Parameters ◽  
Average Grain Size ◽  
Zk60 Magnesium Alloy ◽  
Refinement Effect

The microstructural evolution of of as-cast ZK60 magnesium alloy processed by cyclic extrusion and compression (CEC) were studied, and the effects of technical parameters on microstructural evolution were investigated. The results show that the grains of as-cast ZK60 magnesium alloy were obviously refined and uniformed by CEC, the average grain size was decreased from original 50 ~ 60 μm to about 2 μm when the extrusion ratio was 8 with 8-passes at 350°C, and the refinement effect was increased with the rising of extrusion ratio and passes. The effect of increasing passes on grain refinement was not obvious when it exceeds 8. Nevertheless, it is beneficial for the grain homogenization.

Modeling of grain refinement: Part II. Effect of nucleant particles—TiB2 additions for aluminum

2008 ◽  
Vol 23 (5) ◽  
pp. 1292-1300 ◽  
Author(s):  
X. Yao ◽  
S.D. McDonald ◽  
A.K. Dahle ◽  
C.J. Davidson ◽  
D.H. StJohn
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Grain Refinement ◽  
Master Alloy ◽  
Commercial Purity ◽  
Grain Formation ◽  
Microstructure Morphology ◽  
The Relationship

Following the discussion of modeling grain refinement in Part I, [X. Yao, et al., J. Mater. Res.23(5), 1282, the effect of Al–Ti–B master alloy additions on grain formation in commercial-purity (CP) aluminum was investigated. The characteristics of the addition particles as applicable to the model are presented. The effect of adding TiB2 particles, the introduction of extra particles by reactions in the melt, and the effect of adding extra solute Ti are all modeled. The distribution of the potential particles and its effect on grain formation was also modeled to establish the relationship between the grain size and microstructure morphology and the additive characteristics. The calculated results are comparable with experimental data. Accordingly, possible mechanisms of grain refinement with Al–Ti–B refiners were proposed.

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