scholarly journals (Lecture on ordered intermetallic alloys)

1990 ◽  
Author(s):  
C Liu
Keyword(s):  
Intermetallic Alloys ◽  
Ordered Intermetallic

Bonding and stability in the ordered alloys FeV and CoTi. Comparison with FeTi

1985 ◽  
Vol 50 (10) ◽  
pp. 2093-2100
Author(s):  
Štěpán Pick ◽  
Mojmír Tomášek ◽  
Mojmír Šob
Keyword(s):  
Phase Diagrams ◽  
Partial Wave ◽  
Partial Wave Analysis ◽  
Intermetallic Alloys ◽  
Wave Analysis ◽  
Ordered Alloys ◽  
Ordered Intermetallic ◽  
Cscl Structure ◽  
Ionic Effects

Partial wave analysis together with the qualitative examination of hybridization has been performed for two ordered intermetallic alloys with CsCl structure, FeV, and CoTi. The results resemble those obtained previously for FeTi, although important deviations are present as well. The stabilization of the ordered phase is again due to ionic effects. Qualitative arguments are suggested to explain the small stability of the CsCl phase of FeV and some differences in the FeTi and CoTi phase diagrams.

Ordered intermetallic alloys, part I: Nickel and iron aluminides

JOM ◽  
1993 ◽  
Vol 45 (5) ◽  
pp. 38-44 ◽  
Author(s):  
C. T. Liu ◽  
K. S. Kumar
Keyword(s):  
Iron Aluminides ◽  
Intermetallic Alloys ◽  
Ordered Intermetallic

Atomistic Computer Modeling of Intermetallic Alloys

2005 ◽  
Vol 502 ◽  
pp. 21-26 ◽  
Author(s):  
Yuri M. Mishin
Keyword(s):  
Computer Modeling ◽  
Atomic Diffusion ◽  
Intermetallic Alloys ◽  
Empirical Potentials ◽  
Atomic Interactions ◽  
Ordered Intermetallic ◽  
Interphase Boundaries ◽  
Dislocation Behavior ◽  
Semi Empirical ◽  
Expansion Point

The paper gives a brief overview of our recent work on atomistic computer modeling of ordered intermetallic compounds of the Ni-Al and Ti-Al systems. Atomic interactions in these systems are modeled by semi-empirical potentials fit to experimental and first-principles data. The methodology includes a large variety of techniques ranging from harmonic lattice dynamics to molecular dynamics and Monte Carlo simulations. The properties studied include lattice characteristics (elastic constants, phonons, thermal expansion), point-defect properties, atomic diffusion, generalized stacking faults, dislocations, surfaces, grain boundaries, interphase boundaries, and phase diagrams. We especially emphasize the recent progress in the understanding of diffusion mechanisms in NiAl and TiAl, calculation of stacking fault energies in Ni3Al in relation to dislocation behavior, and calculations of / 0 interface boundaries in Ni-Al alloys.

Investigation of B2 and Related Phases in Ti-Modified Nb-Al Alloys

1993 ◽  
Vol 322 ◽  
Author(s):  
D.-H. Hou ◽  
S.S. Yang ◽  
J. Shyue ◽  
H.L. Fraser
Keyword(s):  
Site Occupancy ◽  
Orthorhombic Phase ◽  
Intermetallic Alloys ◽  
Heat Treated ◽  
Three Phase ◽  
Ordered Intermetallic ◽  
Tie Lines ◽  
Second Phases ◽  
A15 Phase ◽  
O Phase

AbstractThe B2 ordering and phase stability of three ordered intermetallic alloys with compositions (in at.%) of Nb-15Al-10Ti (10Ti alloy), Nb-15A1-40Ti (40Ti alloy), and Nb-15Al-25Ti (25Ti alloy) have been studied. All three alloys have the B2 crystal structure in the as-cast form. The Atom Location by Channeling Enhanced Microanalysis (ALCHEMI) technique has been employed to assess the site occupancy of these B2 alloys. The results of site occupancy are represented as Ordering Tie Lines on a ternary composition diagram. Various second phases were observed in heat treated samples. An ω-type phase was found in the 1OTi alloy in samples heat treated for 10 minutes and 4 hours at 900°C. At 800°C, orthorhombic phase was found in the 40Ti alloy while a three phase microstructure of o-phase/B2/A15 was observed in both the 10Ti and 25Ti alloys. Annealing at 1100°C leads to the dissolution of the o-phase and the presence of A15 phase in the 10Ti and 25Ti alloys, but no other phase in the 40Ti alloy. The observed phase equilibria in these alloys are compared with those in the literature.

Micromechanisms of yield and flow in ordered intermetallic alloys

1988 ◽  
Vol 36 (11) ◽  
pp. 2935-2946 ◽  
Author(s):  
M.H. Yoo ◽  
J.A. Horton ◽  
C.T. Liu
Keyword(s):  
Intermetallic Alloys ◽  
Ordered Intermetallic

Atomistic Modeling Of Ternary And Quaternary Ordered Intermetallic Alloys

2000 ◽  
Vol 646 ◽  
Author(s):  
Guillermo Bozzolo ◽  
Joseph Khalil ◽  
Matthew Bartow ◽  
Ronald D. Noebe
Keyword(s):  
Solubility Limit ◽  
Site Preference ◽  
Atomistic Modeling ◽  
Intermetallic Alloys ◽  
Β Phase ◽  
Local Environments ◽  
Ordered Intermetallic ◽  
Fe Alloys

ABSTRACTThe structure of ternary and quaternary NiAl-based ordered intermetallic alloys is studied using the BFS method for alloys. A simple calculational procedure, based on the determination of the energetics of local environments surrounding defect atoms is introduced and applied to the study of the defect structure and phase formation in NiAl-based systems. The procedure is illustrated with two different examples: 1) the phase structure of Ni-Al-Fe alloys, focusing on the concentration dependence of the site preference behavior of Fe in NiAl, and 2) the precipitation of a β′ phase in NiAl(Ti,Hf) alloys, focusing on the role of Hf in lowering the solubility limit of Ti in NiAl, thus enhancing the precipitation of a Heusler Ni2Al(Ti,Hf) phase.

The disordering process in an Ll2 ordered alloy

1984 ◽  
Vol 42 ◽  
pp. 486-487
Author(s):  
J. A. Horton ◽  
A. DasGupta ◽  
C. T. Liu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Temperature ◽  
Intermetallic Alloys ◽  
Antiphase Boundaries ◽  
High Temperature Mechanical Properties ◽  
Heat Treated ◽  
Ordered Intermetallic

Ordered intermetallic alloys potentially have good high temperature mechanical properties which often are obtained by macroalloying. Since service temperatures may be near the critical ordering temperature, Tc, it is important to understand the disordering processes. The disordering mechanism in an alloy of 52.5 at. % Ni—22.5 Fe—14.5 V—10 Al—0.5 Ti [which can be expressed as (Ni70Fe30)3(V58Al40Ti2)], will be presented here. The aluminum was added to increase Tc from 750 to 975°C and stabilize the Ll2 structure.All specimens were first fully ordered by a heat treatment consisting of 30 min at 1000°C, 1 d at 700°C and 2 d at 600°C which results in a “swirl” pattern of antiphase boundaries (APB) similar to Fig. 1. Specimens were then heat-treated for 24 h at temperatures from 600 to 950°C in 50°C increments and water quenched.

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