Atomistic Studies of Deformation Mechanism of Nanocrystalline Al-Ti and Al-Fe Alloys from First-Principles

2007 ◽  
Vol 561-565 ◽  
pp. 977-980 ◽  
Author(s):  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Solid Solution ◽  
Yield Strength ◽  
First Principles ◽  
Misfit Strain ◽  
First Principles Calculation ◽  
High Yield ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Analytical Result ◽  
Good Agreement

We investigated the contribution to the high yield strength due to the solid solution strengthening in nanocrystalline Al-Ti alloys produced by a vapor quench method. The misfit strain due to solute Ti atom in aluminum was obtained from the first principles calculation. Then, the theoretical result of the contribution to the yield strength due to the solid solution strengthening was estimated from the misfit strain using the Friedel’s theory. In dilute Al-Ti alloy, the theoretical results of the solid solution strengthening from the misfit strain was in good agreement with the analytical result using the measured grain size and yield stress.

Deformation Mechanism of Nanocrystalline Al-Fe Alloys by Analysis from Ab-Initio Calculations

2006 ◽  
Vol 503-504 ◽  
pp. 209-214 ◽  
Author(s):  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Experimental Data ◽  
Solid Solution ◽  
Yield Strength ◽  
First Principles ◽  
High Strength ◽  
Misfit Strain ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Fe Alloys ◽  
Quench Method

Recently nanocrystalline Al-Fe alloys produced by a vapor quench method have been reported. These alloys are supersaturated solid solution and exhibit high strength with good ductility. It is postulated that the high strength of the Al-Fe alloys could be achieved by both the nano-grained structures and the solid solution strengthening. The contribution to the yield strength due to both the grain size strengthening and the solid solution strengthening were analyzed from the experimental data. Then the contribution to the yield strength due to the solid solution strengthening was estimated from the misfit strain calculated from the first principles in order to compare with analytical results estimated from the experimental data.

Mechanical Strength Modeling of Particle Strengthened Nickel-Aluminum Alloys Strengthened by Intermetallic γ′ (Ni3Al) Precipitates

1999 ◽  
Author(s):  
James M. Fragomeni
Keyword(s):  
Yield Strength ◽  
Misfit Strain ◽  
Nickel Aluminum ◽  
Solid Solution Strengthening ◽  
Peak Aged Condition ◽  
Peak Aged ◽  
Solution Strengthening ◽  
Particle Strengthening ◽  
Strength Modeling ◽  
Good Agreement

Abstract A Nickel-Aluminum alloy strengthened by γ′ (Ni3Al) intermetallic ordered coherent precipitates with a small misfit strain was used a demonstration material to develop a model to predict strengthening behavior during plastic deformation as a consequence of the γ′ particles acting as obstacles to the dislocations and thus impeding their glide motion through the alloy. It was determined that the two most dominate strengthening mechanisms in the Ni-Al system were order hardening when the particles were smaller than the critical looping radius, and Orowan strengthening when the particles were larger than the looping radius. In the overaged condition when the particles are large in size, the dislocations bypass and loop the particles by the Orowan mechanism. In the underaged to peak aged conditions where the particles are usually smaller than the looping radius, the dislocations shear the precipitates during deformation. The total polycrystalline yield strength included contributions from the intrinsic lattice strength, the solid solution strengthening, grain size strengthening, and particle strengthening which included the order hardening and Orowan strengthening contributions. The total mechanical yield strength for a Ni-6.27wt.%A1 alloy was predicted for the peak-aged condition based on the theory for order strengthening and was found to be in good agreement with the experimental peak-strength data for Ni-6.27A1.

Effect of APB Microsegregation on the Strength of Ni3Al with Ternary Additions

1990 ◽  
Vol 213 ◽  
Author(s):  
Y.P. WU ◽  
J.M. Sanchez ◽  
J.K. Tien
Keyword(s):  
Solid Solution ◽  
Theoretical Model ◽  
Yield Strength ◽  
Local Concentration ◽  
Antiphase Boundaries ◽  
Alloying Additions ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Ternary Additions ◽  
Ternary Intermetallic Compounds

ABSTRACTSolid solution strengthening for stoichiometric and non-stoichiometric alloys is studied using a microscopic model that takes into account the micro-segregation of the alloying additions and of the host atoms to antiphase boundaries. Experimental results for four ternary intermetallic compounds, Ni-Al-Si, Ni-Al-Ti, Ni-Al-Hf and Ni-Al-V, are analyzed in the light of the theoretical model. It is found that the athermal increment of yield strength for both stoichiometric and non-stoichiometric alloys can be explained using solid solution strengthening theory provided that the local concentration at the {111} antiphase boundaries between superpartial dislocations is used.

Quantification of High Temperature Strength of Nickel-Based Superalloys

2007 ◽  
Vol 546-549 ◽  
pp. 1319-1326 ◽  
Author(s):  
Zhan Li Guo ◽  
N. Saunders ◽  
Alfred Peter Miodownik ◽  
J.P. Schille
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Tensile Deformation ◽  
Model Development ◽  
High Temperature Strength ◽  
Solid Solution Strengthening ◽  
Wide Range ◽  
Solution Strengthening ◽  
Deformation Modes ◽  
Good Agreement

The strength of nickel-based superalloys usually consists of solid solution strengthening from the gamma matrix and precipitation hardening due to the gamma' and/or gamma" precipitates. In the present work, a model was developed to calculate the high temperature strength of nickel-based superalloys, where the temperature dependence of each strengthening contribution was accounted for separately. The high temperature strength of these alloys is not only a function of microstructural changes in the material, but the result of a competition between two deformation modes, i.e. the normal low to mid temperature tensile deformation and deformation via a creep mode. Extensive validation had been carried out during the model development. Good agreement between calculated and experimental results has been achieved for a wide range of nickel-based superalloys, including solid solution alloys and precipitation-hardened alloys with different type/amount of precipitates. This model has been applied to two newly developed superalloys and is proved to be able to make predictions to within useful accuracy.

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