Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tsuru, Tomohito; Liang, Q.*; Daryl, C.*; Yamaguchi, Masatake; Itakura, Mitsuhiro
no journal, ,
Solution strengthening is a well-known approach to tailoring the mechanical properties of structural alloys. Ultimately, the properties of the dislocation/solute interaction are rooted in the electronic structure of the alloy. We investigate the effects of solute atoms on dislocation core structure and motion in hexagonal close-packed metals, especially, Mg and Ti. Using density functional theory calculations, we compute the interaction between solute and dislocation core based on the electronic structure. The analysis suggests that Y and some alkaline-earth atoms and transition metal with a few d electrons produce attractive interaction with a screw dislocation in Mg. The calculations also show that an interstitial O atom provides short-range repulsive interaction with the dislocation core in Ti.
Tsuru, Tomohito; Somekawa, Hidetoshi*; Yamaguchi, Masatake; Itakura, Mitsuhiro; Daryl, C.*
no journal, ,
We investigated the dislocation core structure of some typical HCP metals and the effects of solute atoms on dislocation core structure and motion in Mg especially. An initial atomic configuration is constructed by solving for the displacement field of the dislocation dipole within a periodic continuum linear elasticity theory. DFT calculations were carried out to explore the stable dislocation core structure. Introduction of a substitutional/interstitial solute atom changes the electronic structure near the solute. If these changes occur in the same energy range associated with the changes in the electronic structure of the dislocation during motion, strong chemical hybridization can occur between the solute atom states and those states associated with dislocation motion. DFT calculations also give some information about the tendency of twin boundary cohesion/decohesion due to the solutes.
Tsuru, Tomohito; Itakura, Mitsuhiro; Daryl, C.*
no journal, ,
First-principles calculations were carried out to evaluate direct interaction between oxygen interstitial and a screw dislocation.
Tsuru, Tomohito; Suzudo, Tomoaki; Wakeda, Masato*; Ogata, Shigenobu*; Daryl, C.*
no journal, ,
Tungsten (W) is a potential candidate for plasma-facing materials in fusion reactors due to its high melting point and high thermal conductivity. Neutron irradiation transmutes W into other 5d metals such as rhenium (Re) and osmium (Os). We have so far carried out first-principles and kinetic Monte Carlo calculations to investigate the formation of radiation defects such as voids and radiation-induced precipitates in W alloys. In the present study, we investigate in detail the effects of Re and other 5d solutes on the interaction energy with a screw dislocation and the energy barrier for the dislocation motion through DFT calculations. Finally, solution hardening/softening behavior is reproduced by combining the DFT results with a theoretical model.
Tsuru, Tomohito; Suzudo, Tomoaki; Wakeda, Masato*; Ogata, Shigenobu*; Daryl, C.*
no journal, ,
Tungsten (W) is a potential candidate for plasma-facing materials in fusion reactors due to its high melting point and high thermal conductivity. Neutron irradiation transmutes W into other 5d metals such as rhenium (Re) and osmium (Os). We have so far carried out first-principles and kinetic Monte Carlo calculations to investigate the formation of radiation defects such as voids and radiation-induced precipitates in W alloys. In the present study, we investigate in detail the effects of Re and other 5d solutes on the interaction energy with a screw dislocation and the energy barrier for the dislocation motion through DFT calculations. Finally, solution hardening/softening behavior is reproduced by combining the DFT results with a theoretical model.
Tsuru, Tomohito; Yamaguchi, Masatake; Itakura, Mitsuhiro; Daryl, C.*
no journal, ,
To clarify the energy differences between various dislocation cores, we evaluated possible core structures and motion in Ti. The energy difference between most stable pyramidal and prismatic cores is very small, whereas that between the prismatic and basal cores is larger, thereby preventing dislocation motion in the basal plane in pure Ti. However, the Peierls barrier for motion in the basal plane is not as high if the dislocation exists in the basal core. Direct calculations for the dislocation core around solutes revealed that Al solute facilitate dislocation motion in the basal plane by reducing the energy difference between the core structures while these solutes have a reverse trend for the interaction energy with the dislocation core.