materials-logo

Journal Browser

Journal Browser

Special Issue "High Temperature Alloys and Intermetallic Materials"

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

Deadline for manuscript submissions: closed (30 December 2020).

Special Issue Editor

Prof. SARA BIAMINO
E-Mail Website
Guest Editor
Politecnico di Torino, Department of Applied Science and Technology, Torino, Italy
Interests: additive manufacturing; high temperature materials; Ni superalloys; Titanium Aluminides; titanium alloys; relationships microstructure-properties

Special Issue Information

Dear Colleagues,

Nowadays the request for materials able to efficiently operate at ever-higher service temperatures is continuously pushing research activities in many industrial sectors. In particular, in the field of power generation, aerospace and automotive, it is of fundamental importance in order to increase the efficiency of the engines, thus reducing fuel consumption and pollutant emissions moving towards greener engines. Ever-higher temperatures mean moving to ever-more severe conditions for materials that require improved mechanical properties, but also oxidation and corrosion resistance.

The Special Issue, “High Temperature Alloy and Intermetallic Materials”, will address advances in materials science, processing, characterization, new components development as well as the testing of new systems of materials for high temperatures, thus providing readers with up-to date information on the recent progress from different perspectives.

It is my pleasure to invite you to submit a manuscript to this Special Issue. Original papers are solicited on metallic alloys and intermetallic materials in the following areas:

  • New chemical compositions for increased properties
  • New processing routes
  • New characterizations
  • New coatings for thermal protection
  • New findings in their oxidation and corrosion

Full papers, communications and reviews are all welcome.

Prof. SARA BIAMINO
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 semimonthly 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 2000 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

  • Metallic alloys
  • intermetallics
  • new alloys
  • coatings
  • processing routes
  • microstructure characterization
  • mechanical properties
  • oxidation
  • corrosion

Published Papers (8 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Article
Structure and Properties of Cast Ti-Al-Si Alloys
Materials 2021, 14(4), 813; https://doi.org/10.3390/ma14040813 - 08 Feb 2021
Cited by 1 | Viewed by 565
Abstract
Intermetallic compounds based on Ti-Al- (Si) are attractive materials with good thermal stability and low density. However, the production of these materials is quite complicated. Partially modified conventional methods of melting metallurgy are most often used due to availability, possible high productivity, and [...] Read more.
Intermetallic compounds based on Ti-Al- (Si) are attractive materials with good thermal stability and low density. However, the production of these materials is quite complicated. Partially modified conventional methods of melting metallurgy are most often used due to availability, possible high productivity, and relatively low production costs. Therefore, some technologies for the production of intermetallics based on Ti-Al are currently available, but with certain disadvantages, which are caused by poor casting properties or extreme reactivity of the melt with crucibles. Some shortcomings can be eliminated by modifying the melting technology, which contributes to increasing the cost of the process. The work deals with the preparation of Ti-Al-Si intermetallic compounds with different contents of aluminum and silicon, which were produced by centrifugal casting in an induction vacuum furnace Linn Supercast-Titan. This process could contribute to the commercial use of these alloys in the future. For this research, the TiAl15Si15(in wt.%) alloy was selected, which represents a balanced ratio of aluminides and silicides in its structure, and the TiAl35Si5 alloy, which due to the lower silicon content allows better melting conditions, especially with regard to the melting temperature. This alloy was also investigated after HIP (“Hot Isostatic Pressing”) treatment. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Article
Thermal Expansion of a Multiphase Intermetallic Ti-Al-Nb-Mo Alloy Studied by High-Energy X-ray Diffraction
Materials 2021, 14(4), 727; https://doi.org/10.3390/ma14040727 - 04 Feb 2021
Cited by 2 | Viewed by 598
Abstract
Intermetallic γ-TiAl-based alloys are lightweight materials for high-temperature applications, e.g., in the aerospace and automotive industries. They can replace much heavier Ni-based alloys at operating temperatures up to 750 °C. Advanced variants of this alloy class enable processing routes that include hot forming. [...] Read more.
Intermetallic γ-TiAl-based alloys are lightweight materials for high-temperature applications, e.g., in the aerospace and automotive industries. They can replace much heavier Ni-based alloys at operating temperatures up to 750 °C. Advanced variants of this alloy class enable processing routes that include hot forming. These alloys consist of three relevant crystallographic phases (γ-TiAl, α2-Ti3Al, βo-TiAl) that transform into each other at different temperatures. For thermo-mechanical treatments as well as for adjusting alloy properties required under service conditions, the knowledge of the thermal expansion behavior of these phases is important. Therefore, thermal expansion coefficients were determined for the relevant phases in a Ti-Al-Nb-Mo alloy for temperatures up to 1100 °C using high-energy X-ray diffraction. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Article
Recovery and Characterization Studies of Post-Production Alloy Waste from the Automotive Industry
Materials 2020, 13(24), 5600; https://doi.org/10.3390/ma13245600 - 08 Dec 2020
Cited by 1 | Viewed by 729
Abstract
Superalloys provide high corrosion resistance and are widely used as high-performance materials in aerospace, automotive, chemical, and other industries. Herein, the investigation into the characteristics and properties of alloy waste; Inconel 625, Inconel 718, and Titanium Grade 5, from the automotive industry, was [...] Read more.
Superalloys provide high corrosion resistance and are widely used as high-performance materials in aerospace, automotive, chemical, and other industries. Herein, the investigation into the characteristics and properties of alloy waste; Inconel 625, Inconel 718, and Titanium Grade 5, from the automotive industry, was introduced as a result of a recovery in various processes. For this reason, the following procedures were carried as follows; the washing process to remove oil from the swarf was evaluated using several commercial agents and for the process of thermal disposal of processing fluids, a temperature of 900 °C was used in a muffle furnace without air access. The presented studies show that the commercially available series of washing agents did not modify the composition of the surface. However, the high temperatures during the calcination of oil residues are affecting the elemental composition of the alloys. According to the results of the analyses, it is not possible to remove 100% of the oil residues from alloy waste using washing agents based on light organic fractions; however, the effectiveness of this method reaches 99%. In this report, accurate SEM-EDS analyses show changes that occur on the surface after machining and removal of processing fluids. The NMR and GC/MS investigations indicate contaminants as a mixture of aliphatic and cycloaliphatic hydrocarbons with carbon numbers from C8–C30. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Article
An Advanced TiAl Alloy for High-Performance Racing Applications
Materials 2020, 13(21), 4720; https://doi.org/10.3390/ma13214720 - 22 Oct 2020
Cited by 8 | Viewed by 734
Abstract
Requirements and strict regulations for high-performance racing applications involve the use of new and innovative lightweight structural materials. Therefore, intermetallic γ-TiAl-based alloys enable new opportunities in the field due to their lower density compared to commonly used Ni-base superalloys. In this study, a [...] Read more.
Requirements and strict regulations for high-performance racing applications involve the use of new and innovative lightweight structural materials. Therefore, intermetallic γ-TiAl-based alloys enable new opportunities in the field due to their lower density compared to commonly used Ni-base superalloys. In this study, a β-solidifying TiAl alloy was examined toward its use as structural material for inlet and outlet valves. The nominal composition of the investigated TNM alloy is Ti–43.5Al–4Nb–1Mo–0.1B (in at%), which enables an excellent formability at elevated temperatures due to the presence of bcc β-phase. Different hot-extrusion tests on an industrial scale were conducted on the cast and hot isostatic pressed material to determine the ideal microstructure for the respective racing application. To simulate these operation conditions, hot tensile tests, as well as rotational bending tests, at room temperature were conducted. With a higher degree of deformation, an increasing strength and fatigue limit was obtained, as well as a significant increment of ductility. The fracture surfaces of the rotational bending test specimens were analyzed using scanning electron microscopy, revealing the relationship between crack initiation and microstructural constituents. The results of this study show that the mechanical performance of extruded TiAl material can be tailored via optimizing the degree of hot-extrusion. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Graphical abstract

Communication
Coating Reactions on Vanadium and V-Si-B Alloys during Powder Pack-Cementation
Materials 2020, 13(18), 4099; https://doi.org/10.3390/ma13184099 - 15 Sep 2020
Viewed by 638
Abstract
Alloys in the V-Si-B system are a new and promising class of light-weight refractory metal materials for high temperature applications. Presently, the main attention is focused on three-phase alloy compositions that consist of a vanadium solid solution phase and the two intermetallic phases [...] Read more.
Alloys in the V-Si-B system are a new and promising class of light-weight refractory metal materials for high temperature applications. Presently, the main attention is focused on three-phase alloy compositions that consist of a vanadium solid solution phase and the two intermetallic phases V3Si and V5SiB2. Similar to other refractory metal alloys, a major drawback is the poor oxidation resistance. In this study, initial pack-cementation experiments were performed on commercially available pure vanadium and a three-phase alloy V-9Si-5B to achieve an oxidation protection for this new type of high temperature material. This advance in oxidation resistance now enables the attractive mechanical properties of V-Si-B alloys to be used for high temperature structural applications. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Article
Microstructure and Compression Properties of VSS-V3B2 Eutectic Alloys in the V-Si-B System
Materials 2020, 13(9), 2100; https://doi.org/10.3390/ma13092100 - 01 May 2020
Cited by 1 | Viewed by 1585
Abstract
The present study reports on the microstructural evolution and room temperature plasticity of V(-Si)-B alloys with respect to the V solid solution (VSS)-V3B2 phase region. To investigate the occurring effects systematically, different binary V-B and ternary V-Si-B alloys [...] Read more.
The present study reports on the microstructural evolution and room temperature plasticity of V(-Si)-B alloys with respect to the V solid solution (VSS)-V3B2 phase region. To investigate the occurring effects systematically, different binary V-B and ternary V-Si-B alloys were produced by conventional arc melting. Scanning electron microscope (SEM) analyses and X-ray diffraction (XRD) measurements were used to characterize the resulting as-cast microstructures. For the first time, the eutectic composition was systematically traced from the binary V-B domain to the ternary V-Si-B system. The observations discover that the binary eutectic trough (VSS-V3B2) seems to reach into the ternary system up to an alloy composition of V-5Si-9B. Room temperature compression tests were carried out in order to study the impact of single-phase and multi-phase microstructures on the strength and plasticity of binary and ternary alloys. The results indicate that the VSS phase controls the plastic deformability in the VSS-V3B2 eutectic microstructure whereas the intermetallic V3B2 acts as a strong hardening phase. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Article
Effects of Cr, W, and Mo on the High Temperature Oxidation of Ni-Based Superalloys
Materials 2019, 12(18), 2934; https://doi.org/10.3390/ma12182934 - 11 Sep 2019
Cited by 11 | Viewed by 960
Abstract
The oxidation behavior of Ni–9.5Co–(8~12)Cr–(2.5~5.5)Mo–(4~8)W–3Al–5Ti–3Ta–0.1C–0.01B alloys was investigated at 850 °C and 1000 °C The mass change, the phase of oxides, and the cross-sectional structure of specimens were analyzed after cyclic oxidation tests. The oxide scale was composed mainly of Cr2O [...] Read more.
The oxidation behavior of Ni–9.5Co–(8~12)Cr–(2.5~5.5)Mo–(4~8)W–3Al–5Ti–3Ta–0.1C–0.01B alloys was investigated at 850 °C and 1000 °C The mass change, the phase of oxides, and the cross-sectional structure of specimens were analyzed after cyclic oxidation tests. The oxide scale was composed mainly of Cr2O3 and NiCr2O4, but NiO, TiO2, and CrTaO4 were also found. Al2O3 was formed beneath the Cr oxide layer. The Cr oxide layer and internal Al oxide acted as barriers to oxidation at 850 °C, while Al oxide was predominantly protective at 1000 °C. Cr increased the mass gain after oxidation test at both temperatures. Mo increased the oxidation rate at 850 °C but decreased the oxidation rate at 1000 °C. W slightly increased the mass gain at 850 °C but did not produce a significant effect at 1000 °C. The effects of Cr, Mo, W, and the temperature were discussed as well as the volatilization of oxides, the valence number of elements, and diffusion retardation. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Article
Microstructural Evolution of Post-Processed Hastelloy X Alloy Fabricated by Laser Powder Bed Fusion
Materials 2019, 12(3), 486; https://doi.org/10.3390/ma12030486 - 05 Feb 2019
Cited by 24 | Viewed by 2167
Abstract
Hastelloy X (HX) is a Ni-based superalloy which is employed to produce gas turbine and gas-cooled reactor sectors due to its outstanding oxidation resistance and high tensile strength at high temperatures. This alloy can be processed by laser powder bed fusion (LPBF) fabricating [...] Read more.
Hastelloy X (HX) is a Ni-based superalloy which is employed to produce gas turbine and gas-cooled reactor sectors due to its outstanding oxidation resistance and high tensile strength at high temperatures. This alloy can be processed by laser powder bed fusion (LPBF) fabricating complex geometries in a single step. However, post-processing thermal treatments must be applied to generate a suitable microstructure for high-temperature applications. The investigation reports the microstructure evolution of LPBF HX samples under specific post-processing treatments. A hot isostatic pressing (HIP) treatment can close the internal cracks and reduce the residual porosity (less than 0.1%). Moreover, the HIP-triggered recrystallization generated equiaxed grains, while the slow cooling rate generated a film of intergranular carbides (Mo-rich M6C and Cr-rich M23C6) and intragranular carbides (Mo-rich M6C carbides). Therefore, a solution annealing was performed to dissolve the film of carbides which may reduce the ductility. The post solution annealed material consisted of equiaxed grains with ASTM grain size number mainly 4.5-5.5 and inter/intragranular Mo-rich M6C carbides. The microstructure is highly comparable with solution annealed wrought HX alloy. Finally, after simulating short thermal exposure at 745 °C for 6 h, a significant formation of Cr-rich M23C6 carbides was observed strengthening the LPBF HX alloy. Full article
(This article belongs to the Special Issue High Temperature Alloys and Intermetallic Materials)
Show Figures

Figure 1

Back to TopTop