scholarly journals Plastic deformation and fracture behavior of a Fe-modified Al3Ti-base L12 intermetallic alloy

1991 ◽  
Vol 6 (5) ◽  
pp. 957-963 ◽  
Author(s):  
Hu Gengxiang ◽  
Chen Shipu ◽  
Wu Xiaohua ◽  
Chen Xiaofu
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Deformation Mode ◽  
Intermetallic Alloy ◽  
Nominal Composition ◽  
Second Phase ◽  
Compression Tests ◽  
Transmission Electron ◽  
Deformation And Fracture ◽  
Ordered Intermetallic

The microstructure of the ordered intermetallic alloy with a nominal composition of Al66Fe9Ti24 is nearly single-phase L12 structure, with a few second phase agglomerates at some grain corners. Room temperature compression tests showed that this material exhibits a plastic strain of about 11% at fracture. Final fracture of the compression specimens occurred by a shear-off process along a surface oriented about 45 degrees to the compression axis. Fractographic analysis revealed that the fracture is transcrystalline and the fracture mode is mainly quasicleavage plus tearing. Transmission electron microscopy (TEM) was used to explore its deformation mechanisms. The dislocation density was low after homogenization, but is greatly increased during deformation. The deformation mode was found to be 〈110〉 {111} slip instead of twinning as in Al3Ti. The a〈110〉 superdislocations dissociated into two partials of a/3〈211〉-type, bounding a superlattice intrinsic stacking fault (SISF) on the {111} slip plane.

scholarly journals Deformation and fracture behaviour of the γ-TiAl based intermetallic alloys

2021 ◽  
Vol 121 (4) ◽  
Author(s):  
M.N. Mathabathe ◽  
A.S. Bolokang ◽  
G. Govender ◽  
C.W. Siyasiya ◽  
R.J. Mostert
Keyword(s):  
Room Temperature ◽  
Tensile Deformation ◽  
Quaternary Alloy ◽  
Nominal Composition ◽  
Second Phase ◽  
Intermetallic Alloys ◽  
Fracture Surfaces ◽  
Deformation And Fracture ◽  
Cast Condition ◽  
Microstructural Examination

SYNOPSIS The ß-solidifying g-TAl intermetallic alloys of nominal composition Ti-48Al (binary alloy), Ti-48Al-2Nb (ternary alloy), Ti-48Al-2Nb-0.7Cr (quaternary alloy), and Ti-48Al-2Nb-0.7Cr-0.3Si (quinary alloy) (in at.%) were developed. The materials produced were tensile tested at room temperature. The as-cast microstructures and fracture surfaces of the tensile tested specimens were examined using conventional metallographic methods. Microstructural examination indicated that the alloys were comprised of lamellar structures (a2+γ) embedded in columnar dendritic cores in the as-cast condition. However, the quinary alloy contained a T5Si3 second phase. The alloys exhibited no detectable ductility during tensile deformation, indicating the brittleness of all the materials. The fracture surfaces revealed that the alloys failed by translamellar fracture with correspondingly few cleavage facets. Keywords: γ-TlAl based alloys, ß-solidifying, translamellar fracture.

The deformation and fracture of a dual-phase intermetallic alloy

1989 ◽  
Vol 47 ◽  
pp. 320-321
Author(s):  
Michael Larsen
Keyword(s):  
Compression Fracture ◽  
Intermetallic Alloy ◽  
Nominal Composition ◽  
Dual Phase ◽  
Cast Material ◽  
Deformation And Fracture ◽  
Ordered Intermetallic ◽  
Phase Intermetallic ◽  
Tension And Compression ◽  
Two Phases

Ordered intermetallic alloys possess many attractive properties, yet their use as a structural material has been severely limited by a general lack of low temperature ductility. The beta/gamma-prime dual-phase Ni50Fe30A120 (atomic percent) intermetallic alloy has shown remarkable ductility, exhibiting fracture strains in excess of 20% in both tension and compression. This behavior is yet unexplained, thus an investigation was conducted to study the deformation and fracture behavior of this alloy.The material studied was a Ni50Fe30A120 (nominal composition) directionally solidified alloy. TEM specimens were made from the as cast material in an unstrained condition and with a 1% strain in compression. The foils were hand ground to a thickness of about 75 um and electrothinned in a Tenupol twin jet polisher with a methanol-based solution containing 2% perchloric acid and 35% butyl cellosolve at -20C. A JEOL 2000 FX AEM was used to examine the strained and unstrained foils. STEM microanalysis was performed on the unstrained foil with a Phillips CM-12 AEM to determine the composition of the two phases. Finally, the compression fracture surface was studied using a Hitachi S520 SEM.

TEM study on dislocation structures of Al66Fe9Ti24 intermetallic alloy deformed at room temperature

1990 ◽  
Vol 48 (4) ◽  
pp. 478-480
Author(s):  
Chen Shipu ◽  
Wu Xiaohua ◽  
Hu Gengxiang
Keyword(s):  
High Temperature ◽  
Deformation Mechanism ◽  
Room Temperature ◽  
Deformation Mode ◽  
Intermetallic Alloy ◽  
Slip Systems ◽  
Contrast Effects ◽  
Ordered Intermetallic ◽  
Structural Purpose ◽  
Contrast Analysis

The ordered intermetallic AL3Ti has potential for high temperature structural purpose, but is very brittle at ambient temperature. Recently much attention has been paid to the alloying of Al3Ti so as to change its tetragonal DO22 structure to cubic L12. The latter may have sufficient number of slip systems, and ductility improvement looks promising. Our investigation on the L12-type Al66Fe9Ti24 alloy has shown appreciable compressive ductility at room temperature. TEM study was undertaken to explore its deformation mechanism. The deformation mode was found to be the slip of dislocations instead of twinning in AL3Ti. Fig.1a shows a row of a[10 ] superdislocations slipping in (111) glide plane and each of them dissociated into two partials. Contrast analysis delineated that the superpartials are of a/<211>-type. bounding a superlattice intrinsic stacking fault(SISF) with Rf=a/[111]. i.e. a[10 ] → a/3[11 ] + SISF + a/3[2 ], The contrast effects of the partials and faults are typically given in Fig.1b and 1c.

scholarly journals Identification of an Al–Ni–O precipitate in combustion-synthesized NiAl

2000 ◽  
Vol 33 (5) ◽  
pp. 1217-1222
Author(s):  
A. Biswas ◽  
Madangopal K. ◽  
J. B. Singh ◽  
S. K. Roy ◽  
S. Banerjee
Keyword(s):  
Room Temperature ◽  
Point Group ◽  
Composition Analysis ◽  
Second Phase ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Phase Precipitate ◽  
Transmission Electron ◽  
Chemical Composition Analysis

The complete identity of a second-phase precipitate detected by transmission electron microscopy in combustion-synthesized NiAl was established. The crystal structure, including the point group, the space group and the lattice parameters, was determined by convergent and selected-area electron diffraction techniques. Energy dispersive X-ray spectroscopy was used for the determination of the chemical composition. Analysis established the phase to be the solid solution of NiO in Al2O3and presented evidence of the hitherto unreported room-temperature solubility.

Microstructure Evolution of Hydrogenated Ti6Al4V Alloy during Compression

2012 ◽  
Vol 190-191 ◽  
pp. 517-521
Author(s):  
Bao Guo Yuan ◽  
Qiang Chen ◽  
Hai Ping Yu ◽  
Ping Li ◽  
Ke Min Xue ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
True Strain ◽  
True Stress ◽  
Compression Tests ◽  
Transmission Electron ◽  
Good Repeatability

Compression tests of the hydrogenated Ti6Al4V0.2H alloy were carried out using an Instron 5569 machine at room temperature. True stress-strain curves of the hydrogenated Ti6Al4V0.2H alloy under different compressive strains were obtained. Microstructure evolution of the hydrogenated Ti6Al4V0.2H alloy during the process of compression was investigated by optical microscopy and transmission electron microscopy. Results show that true stress-true strain curves of Ti6Al4V0.2H alloy have good repeatability. The deformation of grains, the dislocation density and slipping evolution during the process of compression are discussed.

Research on the Second Phase of Spray Forming Al-8.5Fe-1.3V-1.7Si Aluminum Alloy

2014 ◽  
Vol 886 ◽  
pp. 36-40
Author(s):  
Rong Hua Zhang ◽  
Bao Hong Zhu ◽  
Xiao Ping Zheng
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Room Temperature ◽  
Spray Forming ◽  
Heating Process ◽  
Second Phase ◽  
Transmission Electron ◽  
Second Phases

Heat-resistant Al-8.5Fe-1.3V-1.7Si aluminum alloys were prepared by spray forming technique. The phase transition of deposited alloys from room temperature to 500°C was measured by Differential Scanning Calorimeter. The organization and the second phases of the alloys were observed and studied by transmission electron microscopy. The research results show that No endothermic peak appears in the deposited alloys during heating process, there is no phase transition occur in the alloy during the heating process from room temperature to 500°C. The deposited alloys mainly include α-Al and α-Al12(Fe,V)3Si phase. Under the transmission electron microscopy, there are also a small amount of slug, fan-shaped, needle-like, block, strip second phases, these phases are Al12Fe3Si, Al8Fe2Si, θ-Al13Fe4, Al9FeSi3, Al6Fe.

Synthesis and Characterization of Mechanically Alloyed and HIP-Consolidated Fe-25Al-10Ti Intermetallic Alloy

2000 ◽  
Vol 646 ◽  
Author(s):  
Su-Ming Zhu ◽  
Makoto Tamura ◽  
Kazushi Sakamoto ◽  
Kunihiko Iwasaki
Keyword(s):  
Yield Strength ◽  
Tribological Properties ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Microstructural Characterization ◽  
Intermetallic Alloy ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Positive Temperature ◽  
Compression Tests

ABSTRACTThe present study is concerned with the processing, microstructural characterization, mechanical and tribological properties of fine-grained Fe-25Al-10Ti intermetallic alloy. The alloy was synthesized from elemental powders by mechanical alloying in an attritor-type ball milling system for 100 h, followed by hot isostatic pressing (HIP). After HIP treatment at 1073 K under an ultra-high pressure of 980 MPa, fully dense compacts with a grain size of about 200 nm were produced. Mechanical properties were evaluated by compression tests from room temperature to 1073 K. At room temperature, the alloy exhibits yield strength as high as 2.4 GPa, together with considerable rupture strain of 0.16. The yield strength decreases monotonically with increasing test temperature with no positive temperature dependence observed. The grain growth after high temperature deformation is not severe, indicating that the alloy has a relatively high thermal stability. Finally, tribological properties of the alloy were evaluated by using a ball-on-disk type wear tester and compared with those for gray cast iron, a currently used material for automotive brake rotors.

DIELECTRIC PROPERTIES OF ULTRAFINE Zn-DOPED CaCu3Ti4O12 CERAMIC

2012 ◽  
Vol 02 (01) ◽  
pp. 1250007 ◽  
Author(s):  
LAXMAN SINGH ◽  
U. S. RAI ◽  
K. D. MANDAL ◽  
MADHU YASHPAL
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Single Phase ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sintered Powder

Ultrafine powder of CaCu2.80Zn0.20Ti4O12 ceramic was prepared using a novel semi-wet method. DTA/TG analysis of dry powder gives pre-information about formation of final product around 800°C. The formation of single phase was confirmed by X-ray diffraction analysis. The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm, respectively. Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic. Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.

Microstructural Investigations of the Unusual Deformation Behavior of Nb2Co7

2008 ◽  
Vol 1128 ◽  
Author(s):  
Frank Stein ◽  
Martin Palm ◽  
Georg Frommeyer ◽  
Padam Jain ◽  
Sharvan Kumar ◽  
...  
Keyword(s):  
Deformation Behavior ◽  
Room Temperature ◽  
Single Phase ◽  
Intermetallic Phase ◽  
Shear Bands ◽  
Bulk Sample ◽  
Strain Rates ◽  
Bending Tests ◽  
Optical Scanning ◽  
Transmission Electron

AbstractUsually, single-phase intermetallics in bulk form can easily be crushed into powder by hammering. It was therefore quite a surprise when we found that a bulk sample of the monoclinic intermetallic compound Nb2Co7 could be extensively deformed at room temperature without shattering or fracturing. In a previous paper, results of microhardness, compression, tensile and bending tests were provided and discussed [1]. In order to understand the observed unusual deformation behavior of this intermetallic phase, its hitherto unknown crystal structure has been studied and the microstructure of undeformed and deformed samples has been analyzed in the present investigation by light-optical, scanning electron and transmission electron microscopy. Single-phase specimens deformed at very different strain rates (hammering and conventional compression testing) both show the occurrence of microcracks along grain boundaries which, in compression-deformed specimens, are strongly localized in extended shear bands oriented approximately 45° to the compression axis. The grains adjacent to the microcracks are heavily deformed whereas, away from the sheared regions, the samples remain free of any indication of plastic deformation.

The Observations on Faulted Dipoles in Deformed Tial—Based Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
Y. Gao ◽  
J. Zhu ◽  
Q. G. Cai
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Low Temperature ◽  
Deformation Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Deformation Structure ◽  
Partial Dislocations ◽  
Transmission Electron

AbstractThe deformation structure of polycrystalline TiAl-based alloys after uniaxial compression at temperature range from 77K to 1073K has been examined using transmission electron microscopy. It was observed that a large number of faulted dipoles are commonly present in deformation structure of the alloys compressed at low temperature 77K and room temperature. The nature of the faulted dipoles has been determined to be intrinsic stacking fault lying on {111} plane, bounded by 1/6<112] partial dislocations. A possible mechanism for the formation of the faulted dipoles was suggested. The results of the statistic observation shows that faulted dipoles in deformed Ti-48A1 and Ti-(47–48) Al-X (X = V,Cr,Mn) alloys are less than those in single phase Ti-52A1 alloy, and the number of the faulted dipoles decreases with increasing deformation temperature. The effect of the faulted dipoles on plastic deformation of the alloy was discussed.

Sign in / Sign up

Export Citation Format

Share Document