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Special Issue "Physical Metallurgy of High Performance Alloys"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (15 August 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Shankar M.L. Sastry

Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO. 63130, USA
Website | E-Mail
Interests: severe plastic deformation processing for microstructural refinement and mechanical property improvements of structural materials; sustainable materials; biomimetic materials

Special Issue Information

Dear Colleagues,

Physical metallurgy has always played a key role in the design and development of high performance alloys, and has guided the microstructural modifications needed to produce improvements in strength, toughness, creep resistance, bio compatibility, and other properties. The goal of this Special Issue on physical metallurgy of high performance alloys is to bring together the recent advances, identify gaps in our understanding of the design of high performance alloys, and summarize directions for further research in the field. Structural alloys, as well as functional materials, will be included.

Examples of some of the recent advances in the development of high performance alloys include development of intermetallics-based high performance alloys for high temperature applications, novel processing methods, such as severe plastic deformation for the development of sub-microscopic and nano grained alloys for improved strength and toughness, laser processing and rapid solidification methods for nonequilibrium phase formation and additive manufacturing, tailoring of composition and structure at the atomic scale; development of materials for energy production and energy storage; and bio compatible and biomimetic materials.

Papers for publication in the Special Issue of Materials are invited in all the above classes of materials and in the areas of thermodynamics and structure based alloy design, modeling, and experimental validation; compositional and processing modifications for microstructure modifications and property improvements of high performance alloys; advanced synthesis and processing routes for the development of high performance alloys; state of the art techniques for the fine-scale structural characterization of high performance alloys; in-service performance of the alloys, and any other relevant phenomena. Full papers, communications, and reviews are all welcome.

Prof. Dr. Shankar M.L. Sastry
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • High performance alloys
  • Intermetallics
  • High temperature alloys
  • Nanograined alloys
  • Severe plastic deformation processing
  • Nonequiilibrium phase formation
  • Additive manufacturing
  • Computer simulation and modeling of alloy design and development
  • Laser/electron beam processing
  • Rapid solidification processing
  • Energy-related materials
  • Biomaterials

Published Papers (8 papers)

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Research

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Open AccessArticle Grain Refinement Efficiency in Commercial-Purity Aluminum Influenced by the Addition of Al-4Ti Master Alloys with Varying TiAl3 Particles
Materials 2016, 9(11), 869; doi:10.3390/ma9110869
Received: 7 August 2016 / Revised: 20 October 2016 / Accepted: 21 October 2016 / Published: 26 October 2016
Cited by 2 | PDF Full-text (7109 KB) | HTML Full-text | XML Full-text
Abstract
A series of Al-4Ti master alloys with various TiAl3 particles were prepared via pouring the pure aluminum added with K2TiF6 or sponge titanium into three different molds made of graphite, copper, and sand. The microstructure and morphology of TiAl
[...] Read more.
A series of Al-4Ti master alloys with various TiAl3 particles were prepared via pouring the pure aluminum added with K2TiF6 or sponge titanium into three different molds made of graphite, copper, and sand. The microstructure and morphology of TiAl3 particles were characterized and analyzed by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The microstructure of TiAl3 particles in Al-4Ti master alloys and their grain refinement efficiency in commercial-purity aluminum were investigated in this study. Results show that there were three different morphologies of TiAl3 particles in Al-4Ti master alloys: petal-like structures, blocky structures, and flaky structures. The Al-4Ti master alloy with blocky TiAl3 particles had better and more stable grain refinement efficiency than the master alloys with petal-like and flaky TiAl3 particles. The average grain size of the refined commercial-purity aluminum always hereditarily followed the size of the original TiAl3 particles. In addition, the grain refinement efficiency of Al-4Ti master alloys with the same morphology, size, and distribution of TiAl3 particles prepared through different processes was almost identical. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Open AccessArticle Evaluation of Subsequent Heat Treatment Routes for Near-β Forged TA15 Ti-Alloy
Materials 2016, 9(11), 872; doi:10.3390/ma9110872
Received: 14 August 2016 / Revised: 20 October 2016 / Accepted: 21 October 2016 / Published: 26 October 2016
PDF Full-text (3951 KB) | HTML Full-text | XML Full-text
Abstract
TA15 Ti-alloy is widely used to form key load-bearing components in the aerospace field, where excellent service performance is needed. Near-β forging technology provides an attractive way to form these complicated Ti-alloy components but subsequent heat treatment has a great impact on the
[...] Read more.
TA15 Ti-alloy is widely used to form key load-bearing components in the aerospace field, where excellent service performance is needed. Near-β forging technology provides an attractive way to form these complicated Ti-alloy components but subsequent heat treatment has a great impact on the final microstructure and mechanical properties. Therefore evaluation and determination of the heat treatment route is of particular significance. In this paper, for the near-β forged TA15 alloy, the formation and evolution of microstructures under different subsequent heat treatment routes (annealing, solution and aging, toughening and strengthening) were studied and the cooling mode after forging was also considered. Then, the type and characteristics of the obtained microstructures were discussed through quantitative metallographic analysis. The corresponding mechanical properties (tensile, impact toughness, and fracture toughness) and effects of microstructural characteristics were investigated. Finally, for a required microstructure and performance a reasonable heat treatment route was recommended. The work is of importance for the application and development of near-β forging technology. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Open AccessArticle Microstructure Evolution of HSLA Pipeline Steels after Hot Uniaxial Compression
Materials 2016, 9(9), 721; doi:10.3390/ma9090721
Received: 25 July 2016 / Revised: 16 August 2016 / Accepted: 19 August 2016 / Published: 24 August 2016
Cited by 1 | PDF Full-text (8838 KB) | HTML Full-text | XML Full-text
Abstract
The mechanical properties of the high-strength low-alloy pipeline steels were mainly controlled by the subsequent phase transformations after rolling. The influence of hot uniaxial compression on the phase transformation of acicular ferrite was explored by viewing of the deformation degree, the deformation temperature,
[...] Read more.
The mechanical properties of the high-strength low-alloy pipeline steels were mainly controlled by the subsequent phase transformations after rolling. The influence of hot uniaxial compression on the phase transformation of acicular ferrite was explored by viewing of the deformation degree, the deformation temperature, and the strain rate. The results show that the increase of deformation amounts raises the transformation starting and finishing temperature during the subsequent cooling and also promotes the polygonal ferrite transformation, which leads to the decrease of Vickers hardness accordingly. With the increasing of the deformation temperature, the achieved microstructure becomes coarsened and thus decreases the hardness. As the strain rate increases, the microstructure is refined and thus the hardness increases gradually; increasing the strain rate appropriately is beneficial to the refinement of the microstructure. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Open AccessArticle Tailorable Burning Behavior of Ti14 Alloy by Controlling Semi-Solid Forging Temperature
Materials 2016, 9(8), 697; doi:10.3390/ma9080697
Received: 29 June 2016 / Revised: 9 August 2016 / Accepted: 12 August 2016 / Published: 16 August 2016
Cited by 2 | PDF Full-text (4386 KB) | HTML Full-text | XML Full-text
Abstract
Semi-solid processing (SSP) is a popular near-net-shape forming technology for metals, while its application is still limited in titanium alloy mainly due to its low formability. Recent works showed that SSP could effectively enhance the formability and mechanical properties of titanium alloys. The
[...] Read more.
Semi-solid processing (SSP) is a popular near-net-shape forming technology for metals, while its application is still limited in titanium alloy mainly due to its low formability. Recent works showed that SSP could effectively enhance the formability and mechanical properties of titanium alloys. The processing parameters such as temperature and forging rate/ratio, are directly correlated with the microstructure, which endow the alloy with different chemical and physical properties. Specifically, as a key structural material for the advanced aero-engine, the burn resistant performance is a crucial requirement for the burn resistant titanium alloy. Thus, this work aims to assess the burning behavior of Ti14, a kind of burn resistant alloy, as forged at different semi-solid forging temperatures. The burning characteristics of the alloy are analyzed by a series of burning tests with different burning durations, velocities, and microstructures of burned sample. The results showed that the burning process is highly dependent on the forging temperature, due to the fact that higher temperatures would result in more Ti2Cu precipitate within grain and along grain boundaries. Such a microstructure hinders the transport of oxygen in the stable burning stage through the formation of a kind of oxygen isolation Cu-enriched layer under the burn product zone. This work suggests that the burning resistance of the alloy can be effectively tuned by controlling the temperature during the semi-solid forging process. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Open AccessArticle Effects of Rapid Thermal Annealing on the Structural, Electrical, and Optical Properties of Zr-Doped ZnO Thin Films Grown by Atomic Layer Deposition
Materials 2016, 9(8), 695; doi:10.3390/ma9080695
Received: 12 June 2016 / Revised: 26 July 2016 / Accepted: 9 August 2016 / Published: 13 August 2016
Cited by 1 | PDF Full-text (3730 KB) | HTML Full-text | XML Full-text
Abstract
The 4 at. % zirconium-doped zinc oxide (ZnO:Zr) films grown by atomic layer deposition (ALD) were annealed at various temperatures ranging from 350 to 950 °C. The structural, electrical, and optical properties of rapid thermal annealing (RTA) treated ZnO:Zr films have been evaluated
[...] Read more.
The 4 at. % zirconium-doped zinc oxide (ZnO:Zr) films grown by atomic layer deposition (ALD) were annealed at various temperatures ranging from 350 to 950 °C. The structural, electrical, and optical properties of rapid thermal annealing (RTA) treated ZnO:Zr films have been evaluated to find out the stability limit. It was found that the grain size increased at 350 °C and decreased between 350 and 850 °C, while creeping up again at 850 °C. UV–vis characterization shows that the optical band gap shifts towards larger wavelengths. The Hall measurement shows that the resistivity almost keeps constant at low annealing temperatures, and increases rapidly after treatment at 750 °C due to the effect of both the carrier concentration and the Hall mobility. The best annealing temperature is found in the range of 350–550 °C. The ZnO:Zr film-coated glass substrates show good optical and electrical performance up to 550 °C during superstrate thin film solar cell deposition. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Open AccessArticle Comparison of Ductile-to-Brittle Transition Behavior in Two Similar Ferritic Oxide Dispersion Strengthened Alloys
Materials 2016, 9(8), 637; doi:10.3390/ma9080637
Received: 22 June 2016 / Revised: 14 July 2016 / Accepted: 21 July 2016 / Published: 29 July 2016
Cited by 1 | PDF Full-text (8739 KB) | HTML Full-text | XML Full-text
Abstract
The ductile-to-brittle transition (DBT) behavior of two similar Fe-Cr-Al oxide dispersion strengthened (ODS) stainless steels was analyzed following the Cottrell–Petch model. Both alloys were manufactured by mechanical alloying (MA) but by different forming routes. One was manufactured as hot rolled tube, and the
[...] Read more.
The ductile-to-brittle transition (DBT) behavior of two similar Fe-Cr-Al oxide dispersion strengthened (ODS) stainless steels was analyzed following the Cottrell–Petch model. Both alloys were manufactured by mechanical alloying (MA) but by different forming routes. One was manufactured as hot rolled tube, and the other in the form of hot extruded bar. The two hot forming routes considered do not significantly influence the microstructure, but cause differences in the texture and the distribution of oxide particles. These have little influence on tensile properties; however, the DBT temperature and the upper shelf energy (USE) are significantly affected because of delamination orientation with regard to the notch plane. Whereas in hot rolled material the delaminations are parallel to the rolling surface, in the hot extruded material, they are randomly oriented because the material is transversally isotropic. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Open AccessArticle Enhanced Thermoelectric Performance of Cu2SnSe3-Based Composites Incorporated with Nano-Fullerene
Materials 2016, 9(8), 629; doi:10.3390/ma9080629
Received: 29 June 2016 / Revised: 16 July 2016 / Accepted: 21 July 2016 / Published: 28 July 2016
Cited by 2 | PDF Full-text (6318 KB) | HTML Full-text | XML Full-text
Abstract
In this study, nano-sized fullerene C60 powder was sufficiently mixed with Cu2SnSe3 powder by ball milling method, and the C60/Cu2SnSe3 composites were prepared by spark plasma sintering technology. The fullerene C60 distributed uniformly
[...] Read more.
In this study, nano-sized fullerene C60 powder was sufficiently mixed with Cu2SnSe3 powder by ball milling method, and the C60/Cu2SnSe3 composites were prepared by spark plasma sintering technology. The fullerene C60 distributed uniformly in the form of clusters, and the average cluster size was less than 1 μm. With increasing C60 content, the electrical conductivity of C60/Cu2SnSe3 composites decreased, while the Seebeck coefficient was enhanced. The thermal conductivity of composites decreased significantly, which resulted from the phonon scattering by the C60 clusters located on the grain boundaries of the Cu2SnSe3 matrix. The highest figure of merit ZT of 0.38 was achieved at 700 K for 0.8% C60/Cu2SnSe3 composite. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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Review

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Open AccessReview Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography
Materials 2016, 9(9), 755; doi:10.3390/ma9090755
Received: 19 July 2016 / Revised: 25 August 2016 / Accepted: 26 August 2016 / Published: 6 September 2016
Cited by 7 | PDF Full-text (9606 KB) | HTML Full-text | XML Full-text
Abstract
Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low
[...] Read more.
Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT) offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys. Full article
(This article belongs to the Special Issue Physical Metallurgy of High Performance Alloys)
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