New observations of a nanoscaled pseudomorphic bcc Co phase in bulk Co–Al–(W,Ta) superalloys

Samimi, Peyman; Liu, Y.; Ghamarian, Iman; Song, Jaeyoung; Collins, Peter C.

doi:10.1016/j.actamat.2014.01.056

Cited by 9 publications

(6 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To understand the influence of composition on the oxidation behavior of the Ti-Mo system, a novel combinatorial approach described elsewhere 17,33,34 was adopted whereby a compositionally graded specimen, Ti-xMo (0 £ x£12, all compositions in wt.%) was prepared using an Optomec LENS TM , an additive manufacturing technique, and subsequently exposed to still air at 650°C. Molybdenum was selected because it is an important element in high-temperature Ti alloys, such as b-21S (a b alloy) and Ti6242 (an a + b alloy).…”

Section: Methodologiesmentioning

confidence: 99%

“…The initial dislocation configuration consists of random distributed segments that are pinned at their ends, leading to the operation of the multiplication mechanism based on Frank-Read source activation as in real crystals. The single grain is oriented so that a tensile load is applied with a constant strain rate in a specific crystallographic direction ([0001], [11][12][13][14][15][16][17][18][19][20], and ). The time step is dt = 5 9 10 12 , and the strain rate is constant at 10 3 in the simulation setup.…”

Section: Methodologiesmentioning

confidence: 99%

“…The experimental technique relies on a relatively new method (ASTAR/precession electron diffraction (PED) from NanoMEGAS (Brussels, Belgium)) and analytical postprocessing strategies described in detail elsewhere [16][17][18] to map out dislocation densities with a 1-nm to 3-nm resolution. As these dislocation density maps are based on the local lattice rotation as represented in the fundamental crystallographic zone, it will be possible to deconstruct these dislocation density maps and extract out each type of dislocation, thus quantifying the defect population as a function of the local crystal orientation.…”

Section: Methodologiesmentioning

confidence: 99%

See 2 more Smart Citations

Discovery via Integration of Experimentation and Modeling: Three Examples for Titanium Alloys

Liu

Samimi

Ghamarian

et al. 2014

JOM

Self Cite

View full text Add to dashboard Cite

One key aspect of any integrated computational materials engineering approach is the integration of experiments that provide critical information for the modeling activities. This article describes, using case studies, three examples of critical experiments that have been conducted in an integrated fashion with modeling activities for titanium alloys, providing valuable information in an accelerated manner. The first has been used to identify key microstructural features associated with fracture toughness in Ti-6Al-4V and integrates artificial neural networks and various experimental techniques. The second is associated with defect accumulation in highly constrained titanium structures and integrates a highly innovative characterization technique (precession electron diffraction) and dislocation dynamics. The third is a high-throughput combinatorial technique to understand the oxidation behavior of titanium alloys and couples the experimental effort with the CALPHAD approach. INTRODUCTIONThe composition, microstructure, and defect structures of advanced nonferrous structural alloys are the predominant factors that govern the response of the material to an externally applied stimulus. For example, there will be an elasticplastic response of the material to an externally applied load. Similarly, there will be a compositional and structural evolution in response to thermal excursions. Although these responses are expected to occur, the precise details of the responses are less well understood. integrated computational materials engineering (ICME), or integrated computational materials science and engineering (ICMSE), is a strategy to integrate knowledge, represented by both computation/simulation and high-fidelity experimental databases, from across the composition-microstructure-processing-property paradigm so as to engineer a solution to a design problem. ICME strategies are increasingly being put into service and adding value. 1-4 However, to be effective the individual components must accurately describe materials phenomena.For many structural materials, the precise details of materials response to external stimuli are not well understood. Often, an integrated experimental and computational approach can help elucidate these missing details. While not representing a complete ICME program, each of these integrated activities has provided knowledge that was otherwise lacking. Each of these programs is related to a different problem facing a particular class of nonferrous structural alloys-titanium-based alloys. These include efforts to understand the following: the influence of microstructure on the fracture toughness of a + b-processed Ti-6Al-4V, the influence of defect populations on performance of single-phase and two-phase titanium alloys, and the role of composition on the oxidation behavior of several titanium alloys. The motivation and details of each problem are described separately, as are the conclusions. It is seen that the integration of critical and careful experiments with various modeling schemes ca...

show abstract

Section: Methodologiesmentioning

confidence: 99%

Section: Methodologiesmentioning

confidence: 99%

Section: Methodologiesmentioning

confidence: 99%

See 1 more Smart Citation

Discovery via Integration of Experimentation and Modeling: Three Examples for Titanium Alloys

Liu

Samimi

Ghamarian

et al. 2014

JOM

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, the LENS™ technology has been adopted to study the influence of oxidation on a single specimen, a composition gradient (Ti-xMo; 0 ≤ x ≤ 12 wt%). Such an approach has been used previously for fundamental studies of composition-microstructure-property relationships [19][20][21][22]. The deposited specimen was then subject to a series of oxidation tests at 650 °C for different holding times.…”

Section: Introductionmentioning

confidence: 99%

Systematic Assessment of the Influence of Mo Concentration on the Oxygen Ingress in Ti–Mo System During High Temperature Oxidation

et al. 2015

Self Cite

View full text Add to dashboard Cite

To understand the role of composition in the oxidation behavior of Ti-Mo system and to evaluate the extent of oxygen ingress into the metal substrate during high temperature exposure, a compositionally graded Ti-xMo specimen (0 ≤ x ≤ 12 wt% Mo) was prepared using an additive manufacturing technique, solutionized and then subjected to oxidation tests at 650 °C for different exposure times. The depth of oxygen diffusion, across the composition range, was assessed via change in the local hardness and the results were coupled with quantitative measurement of the oxygen concentration. The concentration of O in the α phase was reduced by 90 % after a short distance of 16 μm from the metal/oxide interface while it remained more or less the same in β phase. The solubility of Mo in α phase also approached zero near the surface as O changed the partition coefficient of this element between α and β phases. It was shown that the addition of Mo reduces the solubility of O in the metal substrate which in turn retards the transition point from parabolic to the linear oxidation stage.

show abstract

“…3. The precession electron diffraction technique has been used to assess the structure factor values based on the intensities of the recorded spot diffraction patterns [79]. Since the diffraction condition is quasi-kinematical, the intensity of the diffraction spots is distributed more accurately.…”

Section: Orientation Microscopy Using Astar  /Precession Electron DImentioning

confidence: 99%

Application of ASTAR/precession electron diffraction technique to quantitatively study defects in nanocrystalline metallic materials

Ghamarian

View full text Add to dashboard Cite

First and foremost, with a deep sense of gratitude, I would like to express my sincere appreciation to my advisor, Dr. Peter Collins, for his endless source of inspiration and encouragement throughout my entire graduate work. He provided me a remarkable freedom to explore novel and exciting research ideas. His far-reaching vision, invaluable support, great guidance and friendship made this dissertation possible.

show abstract

New observations of a nanoscaled pseudomorphic bcc Co phase in bulk Co–Al–(W,Ta) superalloys

Cited by 9 publications

References 27 publications

Discovery via Integration of Experimentation and Modeling: Three Examples for Titanium Alloys

Discovery via Integration of Experimentation and Modeling: Three Examples for Titanium Alloys

Systematic Assessment of the Influence of Mo Concentration on the Oxygen Ingress in Ti–Mo System During High Temperature Oxidation

Application of ASTAR/precession electron diffraction technique to quantitatively study defects in nanocrystalline metallic materials

Contact Info

Product

Resources

About