| |
Records |
Links |
|
Type |
Muraleedharan, K.; Balamuralikrishnan, R.; Das, N. |
| |
Publication |
TEM and 3D atom probe characterization of DMS4 cast nickel-base superalloy |
Volume |
Journal Article |
Pages |
2009 |
| |
Abstract  |
Journal of Materials Science |
|
| |
Corporate Author |
J. Mater. Sci. |
|
Publisher |
44 |
|
Editor |
9 |
| |
Summary Language |
2218-2225 |
Series Editor |
|
|
Abbreviated Series Title |
Cast nickel-base superalloys possess the required mechanical properties (creep resistance and stress rupture life) at elevated temperatures that make them suitable for turbine blades in aero-engines. The origin of these properties lies in the presence of a simple two phase γ-γ' microstructure (with cuboidal γ' particles dispersed in a γ matrix), in spite of the presence of several alloying elements. The cuboidal nature of the γ' particles arises from an optimal misfit between the two phases, which is a function of the composition of γ and γ' phases. In addition, several microstructural issues arising out of the partitioning of the alloying elements influences directly the deformation mechanisms in the γ and γ', and therefore the mechanical properties of the alloy. In this article, we discuss how some of these microstructural issues have been investigated in DMS4, a cast single crystal superalloy, experimentally using TEM and 3DAP techniques. |
| |
Series Issue |
|
ISSN |
|
|
Medium |
|
| |
Expedition |
|
Notes |
|
|
Call Number |
|
|
Contribution Id |
|
|
Serial |
|
URL |
|
ISBN |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ karnesky @ |
|
10534 |
| Permanent link to this record |
| |
|
| |
|
Han, B.Q.; Lee, Z.; Witkin, D.; Nutt, S.; Lavernia, E.J. |
|
Deformation behavior of bimodal nanostructured 5083 Al alloys |
|
Journal Article |
|
2005 |
|
Metallurgical And Materials Transactions A-Physical Metallurgy And Materials Science |
|
Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. |
|
36a |
|
4 |
|
957-965 |
|
|
|
Cryomilled 5083 At alloys blended with volume fractions of 15, 30, and 50 pct unmilled 5083 At were produced by consolidation of a mixture of cryomilled 5083 At and Unmilled 5083 A] powders. A bimodal grain size was achieved in the as-extruded alloys in which nanostructured regions had a grain size of 200 nm and coarse-grained regions had a grain size of I µm. Compression loading in the longitudinal direction resulted in elastic-perfectly plastic deformation behavior. An enhanced tensile elongation associated with the occurrence of a Luders band was observed in the bimodal alloys. As the volume fraction of coarse grains was increased, tensile ductility increased and strength decreased. Enhanced tensile ductility was attributed to the occurrence of crack bridging as well as delamination between nanostructured and coarse-grained regions during plastic deformation. |
|
Univ Calif Davis, Dept Chem Engn & Mat Sci, Davis, CA 95616 USA, Email: bqhan@ucdavis.edu |
|
|
|
|
|
Minerals Metals Materials Soc |
|
|
|
|
|
English |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1073-5623 |
|
|
|
|
|
|
|
|
|
|
|
ISI:000227914900007 |
|
no |
|
NU @ karnesky @ |
|
10025 |
| Permanent link to this record |
| |
|
| |
|
Lagow, B.W.; Robertson, I.M.; Jouiad, M.; Lassila, D.H.; Lee, T.C.; Birnbaum, H.K. |
|
Observation of dislocation dynamics in the electron microscope |
|
Journal Article |
|
2001 |
|
Materials Science And Engineering A |
|
Mater. Sci. Eng. A |
|
309-310 |
|
|
|
445-450 |
|
|
|
Deformation experiments performed in situ in the transmission electron microscope have led to an increased understanding of dislocation dynamics. To illustrate the capability of this technique two examples will be presented. In the first example, the processes of work hardening in Mo at room temperature will be presented. These studies have improved our understanding of dislocation mobility, dislocation generation, and dislocation-obstacle interactions. Zn the second example, the interaction of matrix dislocations with grain boundaries will be described. From such studies predictive criteria for slip transfer through grain boundaries have been developed. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0921-5093 |
|
|
|
|
|
|
|
|
|
|
|
WOS:000169044600089 |
|
no |
|
NU @ m-krug @ |
|
10533 |
| Permanent link to this record |
| |
|
| |
|
Bakhtizin, R. Z.; Valeev, V. G. |
|
Microroughness field emission electron energy distribution and electron-phonon interaction spectroscopy near the metal surface |
|
Journal Article |
|
1988 |
|
Physica Status Solidi A |
|
Phys. Stat. Sol. A |
|
108 |
|
1 |
|
251-255 |
|
Field Emission |
|
Field electron emission is considered from microtips on the metal surface. The possibility is shown of field emission spectroscopy of electron-phonon interaction near the emitting surface and the influence is studied of an increase in the surface potential barrier transparency by application of a weak high-frequency field altering the character of the field electron energy distribution in such a system. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
|
|
4012 |
| Permanent link to this record |
| |
|
| |
|
Jiang, C.; Sordelet, D.J.; Gleeson, B. |
|
Effects of Pt on the elastic properties of B2 NiAl: A combined first-principles and experimental study |
|
Journal Article |
|
2006 |
|
Acta Materialia |
|
|
|
54 |
|
9 |
|
2361-2369 |
|
Platinum; Nickel aluminides; Point defects; First-principles electron theory |
|
First-principles calculations were performed to investigate the effects of Pt addition on the elastic properties of B2 NiAl. By correlating single-crystal elastic constants with point defect concentrations in the context of the Wagner-Schottky model, a general equation is proposed to calculate elastic properties of ternary B2 NiAl-Pt alloys as a function of alloy composition, in which the defect formation parameters were obtained from first-principles supercell calculations. At constant Al content, the calculations showed that the addition of Pt to B2 NiAl will increase its bulk modulus B but decrease both its shear moduli C' and C44. Results from the model calculations were found to be in good agreement with experimental measurements on polycrystalline samples, as well as direct first-principles calculations on special quasirandom structures. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ p-kolli @ |
|
9711 |
| Permanent link to this record |
| |
|
| |
|
Zhou, F.; Lee, J.; Dallek, S.; Lavernia, E.J. |
|
High grain size stability of nanocrystalline Al prepared by mechanical attrition |
|
Journal Article |
|
2001 |
|
Journal of Materials Research |
|
J. Mater. Res. |
|
16 |
|
12 |
|
3451-3458 |
|
|
|
Grain growth in nanocrystalline (nc) Al with a grain size of 26 nm produced by cryogenic mechanical milling was studied through x-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. Grain growth kinetics resembled those of ball-milled nc Fe. For homologous temperatures (T/TM) of 0.61-0.83, the time exponent n from D1/n - D01/n = kt was 0.04-0.28, tending toward 0.5 as T/TM increased. Two grain-growth regimes were distinguished: below T/TM = 0.78 growth ceased at an approximate grain size of 50 nm while at higher temperatures, grain growth proceeded steadily to the submicrometer range. Grain growth over the range of temperatures studied cannot be explained in terms of a single thermally activated rate process. The observed high grain size stability was attributed primarily to impurity pinning drag associated with the grain growth process. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0884-2914 |
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ karnesky @ 2757 |
|
10753 |
| Permanent link to this record |
| |
|
| |
|
Park, Kyung-Tae; Hwang, Duck-Young; Lee, Young-Kook; Kim, Young-Kuk; Shin, Dong Hyuk |
|
High strain rate superplasticity of submicrometer grained 5083 Al alloy containing scandium fabricated by severe plastic deformation |
|
Journal Article |
|
2003 |
|
Materials Science and Engineering A |
|
Mater. Sci. Eng. A |
|
341 |
|
1-2 |
|
273-281 |
|
High strain rate superplasticity; 5083 Al alloy; Scandium; Severe plastic deformation; Ultrafine grains |
|
High strain rate superplasticity (HSRS) was obtained in a commercial 5083 Al alloy by introducing a ultrafine grained structure of 0.3 small mu, Greekm through severe plastic deformation and by adding a dilute amount of scandium (Sc) as a microstructure stabilizer. Tensile tests were carried out on the as-processed sample at temperatures of 623–823 K and initial strain rates of 1×10−3–1×100 s−1. The maximum elongation to failure of 740% was obtained at 773 K and 1×10−2 s−1. HSRS of the alloy was attributed to the combined effects of dynamic recrystallization and preservation of fine recrystallized grains by the presence of Sc. The mechanical behavior of the alloy at 773 K was characterized by a sigmoidal behavior in a plot of stress vs strain rate in the double logarithmic scale. The origin of the sigmoidal behavior was discussed in terms of microstructural evolution during superplastic deformation. An examination of the fractured samples revealed that failure occurred in a brittle manner related to cavitation rather than necking. Cavity stringers were formed parallel to the tensile axis by interlinkage of jagged-shaped isolated cavities along grain boundaries aligned to the tensile axis. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ karnesky @ |
|
585 |
| Permanent link to this record |
| |
|
| |
|
Lee, Woei-Shyan; Chen, Tao-Hsing |
|
Rate-dependent deformation and dislocation substructure of Al–Sc alloy |
|
Journal Article |
|
2006 |
|
Scripta Materialia |
|
Scripta Mater. |
|
54 |
|
8 |
|
1463-1468 |
|
Al–Sc alloy; Strain rate effect; Activation volume; Dislocation |
|
High strength aluminum–scandium (Al–Sc) alloy is impacted at strain rates ranging from 1.2 × 103 s−1 to 5.8 × 103 s−1 at room temperature. The deformation behaviour of Al–Sc alloy is highly dependent on the strain rate. A higher strain rate increases the dislocation density, thereby reducing the size of the dislocation cells. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ karnesky @ |
|
653 |
| Permanent link to this record |
| |
|
| |
|
Lee, S.-W.; Yeh, J.-W. |
|
Superplasticity of 5083 alloys with Zr and Mn additions produced by reciprocating extrusion |
|
Journal Article |
|
2007 |
|
Materials Science and Engineering: A |
|
|
|
460-461 |
|
|
|
409-419 |
|
Aluminum alloys; Extrusion; Superplasticity |
|
In this study, 5083 aluminum alloys modified with grain refiner, 0.25% Zr and 0.46% Mn, were processed by reciprocating extrusion to yield high-strain-rate superplasticity above 400 [degree sign]C and superior room-temperature mechanical properties. Without any prior homogenization treatment, 10 extrusion passes could give the cast billets an equiaxed grain structure with a grain size of about 4.5 [mu]m and a subgrain size about 0.2 [mu]m, and a uniform distribution of fine inclusions and dispersoids in the matrix. The fine-grained structure was stable up to 525 [degree sign]C, giving the alloy a high-strain-rate and low-stress superplasticity over a wide operating temperature of 400-500 [degree sign]C. In the tensile test at 500 [degree sign]C, a maximum elongation of 1013% and a low flow stress of 7.7 MPa at 5 x 10-2 s-1 were achieved. The apparent and true activation energies for low temperatures (300-400 [degree sign]C) without high-strain-rate superplasticity were 220.6 and 208 kJ/mol, respectively, whereas those at high temperatures (400-500 [degree sign]C) were 88.4 and 98.7 kJ/mol, respectively. Further analysis confirms that grain boundary sliding is the dominant mechanism over the high-strain-rate region from 1 x 10-2 to 5 x 10-1 s-1 at 500 [degree sign]C, and power-law breakdown mechanism occurs over the strain rate from 5 x 10-4 to 1 x 10-2 s-1 at 300 [degree sign]C. The high-strain-rate superplasticity was more strongly enhanced by Zr addition than addition of Cr and Mn. Two enhancing mechanisms for the maximum superplastic elongation and the optimum strain rate are proposed. This study concludes that the effectiveness of Zr is caused by the fineness and the coherency of Zr-rich dispersoids in the matrix. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ karnesky @ |
|
9637 |
| Permanent link to this record |
| |
|
| |
|
Kwon, H.; Barlat, F.; Lee, M.; Chung, Y.; Uhm, S. |
|
Influence of Tempering Temperature on Low Cycle Fatigue of High Strength Steel |
|
Journal Article |
|
2014 |
|
ISIJ International |
|
|
|
54 |
|
4 |
|
979-984 |
|
|
|
In this study, the mechanical and low cycle fatigue properties for a heat-treatment steel subjected to quenching and tempering (QT) were evaluated. The steel had a modified chemical composition with respect to a conventional material and was subjected to tempering at various temperatures. It was shown that the material tempered at 250°C exhibited superior fatigue properties in the short life regions. Carbon atom clusters in concentration of 18 at% in martensite were observed using atom probe tomography (APT) for the steel tempered at 250°C. It is believed that these clusters contribute to the improvement of fatigue properties by hindering the motion of dislocations. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
no |
|
NU @ karnesky @ |
|
11486 |
| Permanent link to this record |
