ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

A molecular dynamics study of Fe50-XMXAl50 ternary alloy (M=Ag, Pt, Pd)

MRS Advances ◽  
2020 ◽  
Vol 5 (23-24) ◽  
pp. 1185-1193
Author(s):  
C S Mkhonto ◽  
P E Ngoepe ◽  
H R Chauke
Keyword(s):  
Molecular Dynamics ◽  
Room Temperature ◽  
Mechanical Stability ◽  
Low Cost ◽  
Industrial Applications ◽  
Iron Aluminide ◽  
Intermetallic Alloys ◽  
Room Temperature Ductility ◽  
The Stability ◽  
Experimental Findings

ABSTRACTIron aluminide intermetallic alloys are of great importance in many industries due to their excellent oxidation resistance, low cost, low density, resistance to corrosion and good ductility at room temperature. However, these alloys suffer limited room temperature ductility above 873 K. In this paper, a molecular dynamics-based LAMMPS-EAM was used to model Fe50-XMXAl doped systems with either Ag, Pt or Pd. The lattice side preferences of the dopant were deduced from their energy landscape, and Fe sub-lattices showed promising properties. It was found that the addition of Ag, Pt and Pd enhances the stability of Fe50-XMXAl composition. More importantly, Ag and Pd doped systems gave comparable transition temperatures to experimental findings of 1273 K and 1073 K, respectively. Their thermodynamic and the mechanical stability trends showed promising properties for industrial applications, displaying stability at a high temperature below 1300 K.

Phase Stability, Microstructure and Mechanical Properties in the Multi-Phse Alloys Based on the L12-Ni3(Al,Be)

1994 ◽  
Vol 364 ◽  
Author(s):  
Takahiro Matsuo ◽  
Hideki Hosoda ◽  
Seiji Miura ◽  
Yoshinao Mishima
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Room Temperature ◽  
Vertical Section ◽  
Intermetallic Alloys ◽  
Primary Solidification Phase ◽  
Four Point Bending ◽  
Room Temperature Ductility ◽  
Three Phase ◽  
Multi Phase

AbstractIntermetallic alloys based on the Ll2 Ni3(Al,Be) phase in the ternary Ni-Al-Bc system are prepared so that the alloys are multi-phase with the B2 intermetallic compound NiBe and a Ni primary solid solution denoted as (Ni). Such three-phase alloys, Ni-16 to 20 at%Al-10 at%Be, exhibit good room temperature ductility as measured by four-point bending. In order to examine the phase stabilities and relations among constituent phases, a vertical section of the ternary system is constructed at a constant 10 at%Bc mainly by differential thermal analysis. It is found that improvement in room temperature ductility can be achieved by the formation of a fine mixture of constituent phases during invariant reactions during solidification, which is further enhanced by the co-existence of the Ll2 phase formed as the primary solidification phase.

Improvement of Room Temperature Ductility of Ni3Al by Unidirectional Solidification

1990 ◽  
Vol 213 ◽  
Author(s):  
Toshiyuki Hirano ◽  
Sea-Sung Chung ◽  
Yoshinao Mishima ◽  
Tomoo Suzuki
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Tensile Elongation ◽  
Growth Direction ◽  
Al Alloy ◽  
Transgranular Fracture ◽  
Zone Method ◽  
Room Temperature Ductility ◽  
The Matrix ◽  
Temperature Fracture

ABSTRACTWe present the new promising method to improve the ductility of intermetallic compound, Ni3Al. Stoichiometric and Alrich Ni3A1 were unidirectionally grown at the growth rate of 24 mm/h by a floating zone method (FZ-UDS). The stoichiometric Ni3Al had a columnar-grained and single phase structure, whereas the Al-rich Ni3Al had a Ni3Al matrix with martensite-like precipitates. These alloys exhibited a large tensile elongation along the growth direction at room temperature. Fracture mode is a complete transgranular fracture in the stoichiometric Ni 3Al alloy, and a mixture of transgranular fracture of the matrix and cleavage of the martensite-like precipitates with cracking at the phase boundary in the Al-rich Ni3Al alloys.

Effect of compositional modification on ductility of B2 phase in Ti–Al–Nb intermetallic alloy

2002 ◽  
Vol 17 (10) ◽  
pp. 2611-2614 ◽  
Author(s):  
Feng Tang ◽  
Masuo Hagiwara
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Phase State ◽  
Intermetallic Alloy ◽  
Chemical Compositions ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Room Temperature Ductility ◽  
Single Phase State ◽  
B2 Phase

Room-temperature ductility of two Ti–Al–Nb intermetallic alloys with close chemical compositions was investigated by tensile testing. The two alloys' ductilities in the B2 single-phase state were significantly different, which indicated that the ductility of B2 phase state was sensitive to the chemical composition. The alloy with more ductile B2 phase exhibited higher ductility in O + B2 two-phase state.

Improvement in room temperature ductility of intermetallic alloys through microstructural control

1996 ◽  
Vol 4 ◽  
pp. S171-S179 ◽  
Author(s):  
Yoshinao Mishima ◽  
Masaharu Kato ◽  
Yoshisato Kimura ◽  
Hideki Hosoda ◽  
Seiji Miura
Keyword(s):  
Room Temperature ◽  
Intermetallic Alloys ◽  
Room Temperature Ductility ◽  
Microstructural Control

scholarly journals A systematic ALCHEMI study of Fe-doped NiAl alloys

1995 ◽  
Vol 53 ◽  
pp. 126-127
Author(s):  
I.M. Anderson ◽  
A.J. Duncan ◽  
J. Bentley
Keyword(s):  
Room Temperature ◽  
Site Occupancy ◽  
Solute Concentration ◽  
Site Preference ◽  
Intermetallic Alloys ◽  
Correction Procedure ◽  
Alloying Element ◽  
Alloying Additions ◽  
Site Occupation ◽  
Thermodynamic Variables

ALCHEMI site-occupation studies of alloying additions to ordered aluminide intermetallic alloys have been performed with varying degrees of success, depending on the ionization delocalization correction procedure applied to the data. Most published studies have been applied to just one or two alloys in order to ascertain qualitatively the site-preference of the alloying element. However, quantitative siteoccupancies can be extracted from carefully performed ALCHEMI experiments as long as the data are properly treated for ionization delocalization and anti-site occupancies. Systematic studies can therefore yield the dependence of site-occupancies in alloys on independent thermodynamic variables. The purpose of the present study is to examine the variation in the site-occupancy of Fe in B2-ordered NiAl as a function of solute concentration and alloy stoichiometry.Twelve different alloys were prepared for this study with stoichiometrics Ni50-xAl50Fex (Ni-deficient), Ni50-x/2Al50-x/2Fex (intermediate), and Ni50-xAl50Fex (Al-deficient), with x = 0.25, 2, 5, and 10. All alloys were homogenized at 1300°C for 5 h, step-cooled to room temperature, then annealed at 800°C for 72 h and water quenched.

Ductility Improvement of Direct-Cast Gamma TiAl-Based Alloy Sheet

1996 ◽  
Vol 460 ◽  
Author(s):  
Toshihiro Hanamura ◽  
Keizo Hashimoto
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Tensile Ductility ◽  
Particle Dispersion ◽  
Alloy Sheet ◽  
High Temperature Strength ◽  
High Oxygen Content ◽  
Room Temperature Ductility ◽  
Average Grain Size ◽  
The Matrix

ABSTRACTFor improving the room temperature tensile ductility of direct-cast gamma TiAl sheets without affecting their high-temperature strength, direct sheet casting with T1B2 particle dispersion is employed and conducted. The T1B2 addition and rapid cooling results in the formation of a fine equiaxed grain microstructure with an average grain size of ∼10μm, contributing to the increase in the room temperature ductility to 2.1% with the high-temperature tensile strength kept at about 200MPa. This improvement of room-temperature ductility is attributable to the following fact. The high oxygen content of this material, about 2500wt. ppm, is not harmful to the tensile ductility when the oxygen is in the solid solution of the 0:2 lamellar phase or in oxide particles, which are fine enough not to cause brittleness to the matrix. From these findings, a principle is proposed that oxygen is not harmful to the ductility of gamma TiAl when its microstructure containing oxygen is fine enough.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

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