First-principles calculations for development of low elastic modulus Ti alloys

2004 ◽  
Vol 70 (17) ◽  
Author(s):  
Hideaki Ikehata ◽  
Naoyuki Nagasako ◽  
Tadahiko Furuta ◽  
Atsuo Fukumoto ◽  
Kazutoshi Miwa ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
First Principles ◽  
First Principles Calculations ◽  
Ti Alloys ◽  
Low Elastic Modulus

Phase stability and elastic modulus of Ti alloys containing Nb, Zr, and/or Sn from first-principles calculations

2008 ◽  
Vol 93 (12) ◽  
pp. 121902 ◽  
Author(s):  
Qing-Miao Hu ◽  
Shu-Jun Li ◽  
Yu-Lin Hao ◽  
Rui Yang ◽  
Börje Johansson ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Phase Stability ◽  
First Principles ◽  
First Principles Calculations ◽  
Ti Alloys

scholarly journals The Nucleation and the Intrinsic Microstructure Evolution of Martensite from 332113β Twin Boundary in β Titanium: First-Principles Calculations

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1202 ◽  
Author(s):  
Chen ◽  
Ma ◽  
Wang
Keyword(s):  
Twin Boundary ◽  
Microstructure Evolution ◽  
First Principles ◽  
Atomic Scale ◽  
Clear Understanding ◽  
Intermediate Structure ◽  
First Principles Calculations ◽  
Ti Alloys ◽  
Α Phase ◽  
Strength And Ductility

A clear understanding on the inter-evolution behaviors between 332113β twinning and stress-induced martensite (SIM) α″ in β-Ti alloys is vital for improving its strength and ductility concurrently. As the preliminary step to better understand these complex behaviors, the nucleation and the intrinsic microstructure evolution of martensite α″ from 332113β twin boundary (TB) were investigated in pure β-Ti at atomic scale using first-principles calculations in this work. We found the α″ precipitation prefers to nucleate and grow at 332113β TB, with the transformation of 332113β TB→130310α” TB. During this process, α″ precipitation firstly nucleates at 332113β TB and, subsequently, it grows inwards toward the grain interiors. This easy transition may stem from the strong crystallographic correspondence between 332113β and 130310α” TBs, and the region close to the 332113β TB presents the characteristics of intermediate structure between β and α″ phases. Kinetics calculations indicate the α″ phase barrierlessly nucleates at 332113β TB rather than in grain interior, where there is higher critical driving energy. Our calculations provide a unique perspective on the “intrinsic” microstructure evolution of martensite α″ from 332113β TB, which may deepen our understanding on the precipitation of martensite α″ and the inter-evolution behaviors between 332113β twinning and martensite α″ in β-Ti alloys at atomic scale.

First-Principles Study of the Elastic Properties of Hexagonal Phase ScAx (A=H, He)

2013 ◽  
Vol 690-693 ◽  
pp. 1723-1727
Author(s):  
Kai Min Fan ◽  
Li Yang ◽  
Jing Tang ◽  
Qing Qiang Sun ◽  
Xiao Tao Zu
Keyword(s):  
Elastic Modulus ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
First Principles ◽  
Poisson’S Ratio ◽  
Hexagonal Phase ◽  
Poisson's Ratio ◽  
First Principles Calculations ◽  
Charge Densities ◽  
Change Mechanism

First-principles calculations are performed to investigate the Young’s modulus, bulk modulus, shear modulus and Poisson’s ratio of hexagonal phase ScAx(A=H, He), where x=0, 0.0313, 0.125 and 0.25, represent the ratio of interstitial atoms A (A=H, He) to Sc atoms. The influences of hydrogen concentrations and helium concentrations on elastic modulus and Poisson’s ratio of ScAx(A=H, He) have been studied. The results indicate that hydrogen and helium have different effects on the elastic modulus of hexagonal phase scandium. The change mechanism of the Poisson’s ratio with the variation of the x ranging from 0 to 0.25 has also been studied in hexagonal phase ScAx(A=H, He). In addition, the changes in the charge densities of ScAxdue to the presence of hydrogen and helium have been calculated.

First-principles Investigations of Point Defect Behavior and Elastic Properties of TiNi Based Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
Jian-min Lu ◽  
Qing-miao Hu ◽  
Rui Yang
Keyword(s):  
Elastic Modulus ◽  
Point Defect ◽  
First Principles ◽  
Binary Phase Diagram ◽  
Orbital Method ◽  
Intrinsic Point Defect ◽  
First Principles Calculations ◽  
Potential Approximation ◽  
Early Transition Metal ◽  
Defect Behavior

AbstractFirst-principles calculations by the use of a plane-wave pseudopotential method are performed to investigate intrinsic point defect behavior in TiNi. The results show that TiNi is an antisite type intermetallic compound. The calculated interaction energies between the point defects demonstrate that Ti antisites are attractive to each other whereas Ni antisites are mutually repulsive. The attraction between Ti antisites indicates that excess Ti in TiNi may agglomerate so that a Ti-rich phase can easily precipitate. The repulsion between Ni antisites implies that the excess Ni is of certain solubility in TiNi. This result explains well the asymmetric feature of TiNi field on the binary phase diagram. In order to understand the correlation between the composition dependent elastic modulus and martensitic transformation (MT) temperature, the elastic moduli critical to MT, i.e., c′ and c44, are calculated as a function of the composition of the off-stoichiometric TiNi and a series of ternary TiNi-X alloys, by the use of exact muffin-tin orbital method in combination with coherent potential approximation. It turns out that, generally speaking, the early transition metal (TM) alloying elements in the periodic table increase c′ but decrease c44; the middle ones increase both c′ and c44, whereas the late ones decrease c′ but increase c44. An examination of the theoretical composition dependent elastic modulus and the experimental MT temperature shows that the MT temperature is more sensitive to the variation of c44 than to that of c′.

Stability of α Phase in Ti Alloys Containing Al or Zr from First-Principles Calculations

2013 ◽  
Vol 634-638 ◽  
pp. 1831-1835
Author(s):  
Zhong Bo Zhou ◽  
Hong Chao Kou ◽  
Xiang Yi Xue ◽  
Hui Chang ◽  
Li Jun Zhang ◽  
...  
Keyword(s):  
First Principles ◽  
Plane Waves ◽  
Repulsive Interaction ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Al Content ◽  
Generalized Gradient Approximation ◽  
Ti Alloys ◽  
Α Phase ◽  
The Stability

The energetic and electronic structure of α-type Ti1-xXx (X=Al and Zr, x=0.0625, 0.125, 0.185, 0.250, 0.3125and 0.375) binary alloys were calculated by the method of supercell and augmented plane waves plus local orbitals within generalized gradient approximation. The results show that the formation energy decreases with the composition of Al, while increases with composition of Zr, which indicate that α phase can be enhanced by increasing the Al contents while weaken by increasing Zr contents. The DOS results shows that the Fermi levels of Ti1-x Al x and Ti 1-x Zr x fall on a dip of a DOS curve, which means the α structure of these alloys is stable. When the Al content is increased, the charge transfer between the Al and its neighbors becomes more evident, and enhance the stability of the α phase. With an increase of Zr content, repulsive interaction between two Ti atoms strengthen, which result in the α phase stability decrease.

Structural and elastic properties of Cu6Sn5 and Cu3Snfrom first-principles calculations

2009 ◽  
Vol 24 (7) ◽  
pp. 2361-2372 ◽  
Author(s):  
Jiunn Chen ◽  
Yi-Shao Lai ◽  
Ping-Feng Yang ◽  
Chung-Yuan Ren ◽  
Di-Jing Huang
Keyword(s):  
Electronic Structure ◽  
Elastic Modulus ◽  
Elastic Properties ◽  
First Principles ◽  
Elastic Anisotropy ◽  
Lattice Structure ◽  
Elastic Stiffness ◽  
First Principles Calculations ◽  
Atomic Lattice ◽  
Microstructure Effect

We investigated the elastic properties of two tin-copper crystalline phases, the η′-Cu6Sn5 and ε-Cu3Sn, which are often encountered in microelectronic packaging applications. The full elastic stiffness of both phases is determined based on strain-energy relations using first-principles calculations. The computed results show the elastic anisotropy of both phases that cannot be resolved from experiments. Our results, suggesting both phases have the greatest stiffness along the c direction, particularly showed the unique in-plane elastic anisotropy associated with the lattice modulation of the Cu3Sn superstructure. The polycrystalline moduli obtained using the Voigt-Reuss scheme are 125.98 GPa for Cu6Sn5 and 134.16 GPa for Cu3Sn. Our data analysis indicates that the smaller elastic moduli of Cu6Sn5 are attributed to the direct Sn–Sn bond in Cu6Sn5. We reassert the elastic modulus and hardness of both phases using the nanoindentation experiment for our calculation benchmark. Interestingly, the computed polycrystalline elastic modulus of Cu6Sn5 seems to be overestimated, whereas that of Cu3Sn falls nicely in the range of reported data. Based on the observations, the elastic modulus of Cu6Sn5 obtained from nanoindentation tests admit the microstructure effect that is absent for Cu3Sn is concluded. Our analysis of electronic structure shows that the intrinsic hardness and elastic modulus of both phases are dominated by electronic structure and atomic lattice structure, respectively.

Elastic properties and electronic structure of Mo2FeB2 alloyed with Cr, Ni and Mn by first-principles calculations

2017 ◽  
Vol 31 (12) ◽  
pp. 1750138 ◽  
Author(s):  
Yuan Hua Lin ◽  
Chuang Chuang Tong ◽  
Yong Pan ◽  
Wan Ying Liu ◽  
Ambrish Singh
Keyword(s):  
Electronic Structure ◽  
Elastic Modulus ◽  
Elastic Properties ◽  
First Principles ◽  
Deformation Resistance ◽  
Alloying Elements ◽  
First Principles Calculations ◽  
Volume Deformation ◽  
Covalent Bonds ◽  
G Ratio

In this work, we have applied the first-principles calculations to investigate the structural stability, elastic properties and electronic structure of Mo2FeB2 with alloying elements Cr, Ni and Mn. The calculated cohesive energy shows that Cr, Ni and Mn prefer to occupy the Fe atom of Mo2FeB2. However, only when Mn is doped at the Mo atom of Mo2FeB2, it is converted from dynamic unstable state to stable state. The calculated elastic modulus shows that Mo2FeB2 will have better mechanical properties when alloying elements are at Fe site instead of Mo site. Moreover, Cr addition can improve the volume deformation resistance of Mo2FeB2, Mn addition can improve the shear deformation resistance for Mo2FeB2. The calculated B/G ratio shows that Ni addition can improve the brittleness of borides. Furthermore, the hardness of Mo2FeB2 can be enhanced by adding Cr and Mn element. The calculated electronic structure indicates that the increasing of elastic modulus is attributed to the formation of Cr–B and Mn–B covalent bonds.

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