The Effect of Grain Refinement on the Room-Temperature Ductility of As-Cast Fe3Al-Based Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
S. Viswanathan ◽  
V. K. Andleigh ◽  
C. G. McKamey
Keyword(s):  
Grain Refinement ◽  
Room Temperature ◽  
Maximum Stress ◽  
Cast Alloy ◽  
Room Temperature Ductility ◽  
Bend Tests ◽  
Point Bend ◽  
Carbon Additions ◽  
Cast Condition ◽  
Strength And Ductility

AbstractFe3Al-based alloys exhibit poor room temperature ductility in the as-cast condition. In this study, the effect of grain refinement of the as-cast alloy on room-temperature ductility was investigated. Small melts of Fe-28 at. % Al-5 at. % Cr were inoculated with various alloying additions and cast into a 50- × 30- × 30-mm graphite mold. The resulting ingots were examined metallographically for evidence of grain refinement, and three-point bend tests were conducted on samples to assess the effect on room-temperature ductility. Ductility was assumed to correlate with the strain corresponding to the maximum stress obtained in the bend test. The results showed that titanium was extremely effective in grain refinement, although it severely embrittled the alloy in contents exceeding 1%. Boron additions strengthened the alloy significantly, while carbon additions reduced both the strength and ductility. The best ductility was found in an alloy containing titanium, boron, and carbon.

Effect of chromium on properties of Fe3Al

1989 ◽  
Vol 4 (5) ◽  
pp. 1156-1163 ◽  
Author(s):  
C. G. McKamey ◽  
J. A. Horton ◽  
C. T. Liu
Keyword(s):  
Tensile Strength ◽  
Fracture Mode ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Antiphase Boundary ◽  
Transgranular Cleavage ◽  
Room Temperature Ductility ◽  
Wavy Slip ◽  
Strength And Ductility

The effects of the addition of chromium on several properties of Fe3Al, including tensile strength and ductility, fracture behavior, and slip and dislocation characteristics, were studied. Alloying with up to 6 at. % chromium results in an increase in room temperature ductility from approximately 4% to 8–10%. Along with this increase in ductility, the addition of chromium produces a change in fracture mode from transgranular cleavage to a mixed mode of intergranular-transgranular cleavage, and a change in slip behavior from coarse straight slip to fine wavy slip. These phenomena are discussed in terms of the effect of chromium on the antiphase boundary energies and dislocation characteristics.

scholarly journals Synthesis, Characterization and Mechanical Properties of Nanocrystalline NiAl

1996 ◽  
Vol 457 ◽  
Author(s):  
M. S. Choudry ◽  
J. A. Eastman ◽  
R. J. DiMelfi ◽  
M. Dollar
Keyword(s):  
Room Temperature ◽  
Dark Field ◽  
Inert Gas ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Grain Sizes ◽  
Room Temperature Ductility ◽  
Cast Alloys ◽  
Bend Tests

ABSTRACTNanocrystalline NiAl has been produced from pre-cast alloys using an electron beam inert gas condensation system. In-situ compaction was carried out at 100 to 300°C under vacuum conditions. Energy dispersive spectroscopy was used to determine chemical composition and homogeneity. Average grain sizes in the range of 4 to 10 nm were found from TEM dark field analyses. A compression-cage fixture was designed to perform disk bend tests. These tests revealed substantial room temperature ductility in nanocrystalline NiAl, while coarse grained NiAl showed no measurable room temperature ductility.

Effect of Deformation Processing on Mechanical Properties of Nb-10 a/o Si In-Situ Composite

1993 ◽  
Vol 322 ◽  
Author(s):  
I. Weiss ◽  
M. Thirukkonda ◽  
R. Srinivasan
Keyword(s):  
Fracture Toughness ◽  
Thermomechanical Processing ◽  
Cast Alloy ◽  
Extrusion Direction ◽  
Microstructural Refinement ◽  
In Situ Composite ◽  
Size Refinement ◽  
Bend Tests ◽  
Point Bend

AbstractNb-10 a/o Si alloy is an in-situ composite. The microstructure of the cast alloy consists of pro-eutectic Nb dendrites distributed in a matrix of eutectic Nb3Si + Nb phases. The microstructure of the as-cast alloy was modified by multiple hot extrusions producing an oriented composite. Extensive grain size refinement occurred in both the Nb and Nb3Si phases. The ductile primary (pro-eutectic) Nb particles were aligned along the extrusion direction. Bend strength and fracture toughness measured by three point bend and four point bend tests, respectively, showed that both the yield strength and fracture toughness of the alloy increases considerably following this thermomechanical processing. These improvements have been attributed to the changes in size, morphology and spacing of the constituent phases and their microstructural refinement.

Microstructure and Mechanical Bevavior of Ni3Al-Matrix Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
P. C. Brennan ◽  
W. H. Kao ◽  
S. M. Jeng ◽  
J.-M. Yang
Keyword(s):  
Yield Strength ◽  
Nickel Aluminide ◽  
Fracture Stress ◽  
Room Temperature ◽  
Hot Extrusion ◽  
Matrix Composites ◽  
The Matrix ◽  
Bend Tests ◽  
Point Bend ◽  
Particulate Reinforced

AbstractAn aluminum oxide particulate-reinforced nickel-aluminide composite was fabricated by vacuum hot pressing and hot extrusion. Room temperature three point bend tests were conducted after 1 and 100 h at 1000 °C. The composite exhibited a decrease in yield strength from 772 to 517 MPa after 100 h while the ultimate fracture stress decreased from 1174 to 998 MPa. The strain to failure increased from 4.6% to 6.0% after the same exposure. Saphikon single crystal Al2O3 fibers were used to demonstrate the materials' compatibility. The fracture surfaces of the failed composites indicated ductile failures in the matrix and decohesion between the particles and matrix.

Stoichiometry effects: on the deformation of binary TiAl alloys

1989 ◽  
Vol 4 (3) ◽  
pp. 595-602 ◽  
Author(s):  
Ernest L. Hall ◽  
Shyh-Chin Huang
Keyword(s):  
Melt Spinning ◽  
Room Temperature ◽  
Single Phase ◽  
Temperature Deformation ◽  
Two Phase ◽  
Tial Alloys ◽  
Bend Tests ◽  
Alloy Microstructure ◽  
Mechanical Twins ◽  
Strength And Ductility

The room temperature deformation behavior and microstructure of Ti48Al52 and Ti52Al48 alloys are compared. The material was fabricated by rapid solidification melt spinning, and examined in both as-cast and consolidated forms. The Ti52Al48 alloy exhibited enhanced strength and ductility in both forms in bend tests compared with the Ti48Al52 alloy. The microstructure of the Ti52Al48 alloy was two-phase γ–TiAl and α2–Ti3Al. The Ti48Al52 alloy was single-phase γ–TiAl and had a larger grain size than the previous alloy. The microstructure of the Ti52Al48 alloy after room temperature deformation consisted primarily of {111} mechanical twins and a/2〈110〉 perfect dislocations. The comparable Ti48Al52 alloy microstructure contained fewer twins, and many more a〈101〉 and a/2〈112〉 superdislocations were present in addition to a/2〈110〉 dislocations. The superdislocations had dissociated and formed sessile faulted dipoles. The possible reasons for the differences in microstructure and mechanical behavior between these two alloys are discussed.

Evidence of room temperature ductility in nanocrystalline NiAl from biaxial disk bend tests

1997 ◽  
Vol 37 (6) ◽  
pp. 843-849 ◽  
Author(s):  
M.S. Choudry ◽  
J.A. Eastman ◽  
R.J. DiMelfi ◽  
M. Dollar
Keyword(s):  
Room Temperature ◽  
Room Temperature Ductility ◽  
Bend Tests

Effect of Ductile Phase Reinforcement Morphology on Toughening of MoSi2

1992 ◽  
Vol 273 ◽  
Author(s):  
D. E. Alman ◽  
N. S. Stoloff
Keyword(s):  
Room Temperature ◽  
Matrix Interface ◽  
Short Fibers ◽  
Ductile Phase ◽  
Aligned Fibers ◽  
The Matrix ◽  
Fiber Deformation ◽  
Bend Tests ◽  
Fiber Matrix Interface ◽  
Point Bend

ABSTRACTNiobium was added to MoSi2 in the form of particles, random short fibers and continuous aligned fibers. It was found that the morphology of Nb played a role in the toughening that occurred (as measured by the area under load displacement curves from room temperature three point bend tests and the examination of fracture surfaces). The Nb particles did not toughen MoSi2. The random short fibers appeared to toughen MoSi2 via crack deflection along the fiber matrix interface. Aligned fibers imparted the greatest toughness improvements, as toughening resulted from fiber deformation. However, larger diameter fibers displayed a greater ability to toughen MoSi2 than smaller diameter fibers. This was attributed to the constraint resulting from the interfacial layer between the MoSi2 matrix and the Nb fiber. Maximum toughness occurs when the fiber is able to separate from the matrix and freely deform.

Microstructure and Processing Ability of β-Solidifying TNM-Based γ-TiAl Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 235-240 ◽  
Author(s):  
V.M. Imayev ◽  
Renat M. Imayev ◽  
Timur G. Khismatullin ◽  
T. Oleneva ◽  
Volker Gühter ◽  
...  
Keyword(s):  
Lamellar Structure ◽  
Room Temperature ◽  
Critical Issue ◽  
Hot Workability ◽  
Tial Alloys ◽  
Room Temperature Ductility ◽  
Processing Ability ◽  
Cast Condition

Microstructure and hot workability have been considered for a number of -TiAl alloys including -solidifying TNM alloys. All TNM alloys under study showed improved hot workability in cast condition. As was shown for the Ti-45Al-5Nb-1Mo-0.2B alloy, a critical issue of TNM alloys is room temperature ductility in the conditions with lamellar structure.

Microstructural Studies of the Deformation of TiAl Alloys

1988 ◽  
Vol 133 ◽  
Author(s):  
Ernest L. Hall ◽  
Shyh-Chin Huang
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Alloy Composition ◽  
Two Phase ◽  
Tial Alloys ◽  
Second Phases ◽  
Bend Tests ◽  
Microstructural Studies ◽  
Strength And Ductility

ABSTRACTThe mechanical behavior and microstructures of TiAl alloys after tensile and bend tests at room temperature and elevated temperatures were studied. The results for two-phase Ti52Al48 alloys are compared with those of single phase Ti48Al52, and the effect of adding 3 at. pct. vanadium as a substitute for Ti in these two alloys is considered. It is shown that Ti52Al48 has greater strength and ductility than Ti48Al52 at room temperature and elevated temperatures up to 871°C (1600°F). Adding vanadium increases the ductility of both binary alloys. The microstructure of the Ti52Al48 alloy deformed at room temperature contains primarily twins and 1/2<110> easy slip dislocations, whereas the similar Ti48Al52 sample exhibits superdislocations and associated pinned faulted dipoles. If these samples are deformed at 540°C (1000°F) or above, the Ti52Al48 exhibits extensive twinning, and the pinned faulted dipoles in the Ti48Al52 sample disappear. The vanadium additions do not noticeably change the deformation microstructure at room temperature. It is suggested that the strength and ductility of these alloys may be controlled by tetragonality, bonding, interstitial element, and grain size effects, which in turn are affected by the presence of second phases and by the alloy composition.

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