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News Trends in Powder Metallurgy: Microstructures, Properties, Durability

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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Powder Metallurgy".

Deadline for manuscript submissions: closed (1 May 2021) | Viewed by 45401

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Special Issue Editors

Prof. Dr. Eric Hug

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Guest Editor

CRISMAT Laboratory, UMR 6508, Normandy University, 6 Boulevard Marechal Juin, CEDEX 4, 14050 Caen, France
Interests: plasticity mechanisms; plasticity modelisation; dislocations and twinning; size effects in metals; corrosion; magnetic and electrical properties; spark plasma sintering; additive manufacturing
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Guy Dirras

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Guest Editor

LSPM laboratory, CNRS-UPR 3407, Université Paris 13, 99 avenue Jean Baptiste Clément, 93430, Villetaneuse, France
Interests: powder metallurgy; microstructure characterization, mechanical behavior and analysis of deformation and fracture mechanisms, high strain rate loading; identification of interactions between structural defects; high entropy alloys

Special Issue Information

Dear Colleagues,

Elaboration of sintered metallic alloys is currently one of the main ways of developing structural parts, compared to traditional methods of casting or plastic deformation processes. Recent methods of fast sintering (SPS, microwave sintering) on the one hand and the emergence of additive manufacturing by powder bed melting on the other hand have led to original microstructure design: nanostructured, multimodal, architectured, etc. As a consequence, the mechanical and physical properties of the alloys are deeply modified. In this Special Issue, we propose a review of the scientific advances in this field, covering all the areas concerned, especially (though non-exhaustively):

Toward new microstructures: analysis, properties, and stability ;
Powder properties, nanostructuration, mechanical alloying, and aging;
Unconventional sintering processes: SPS, microwave, etc.;
Additive manufacturing by powder bed melting processes;
Mechanical properties: fatigue, creep, plasticity mechanisms;
Physical properties: magnetism, electrical conduction;
Damage, fracture, effect of the environment: oxidation, electrochemical corrosion.

This Special Issue seeks to provide a selection of original research on the impact of the microstructure on the mechanical and functional properties of metallic alloys obtained by sintering and additive manufacturing routes. Submissions dealing with new microstructures and specific properties of metal powders are also welcome. As Guest Editors of this Special Issue, we invite you to submit your work, which will be peer-reviewed, to be accepted for publication in Metals.

Prof. Eric Hug
Prof. Dr. Guy Dirras
Guest Editors

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 submissions that pass pre-check are 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. Metals 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 2600 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

Powder metallurgy
Sintering
Additive manufacturing
Microstructures
Mechanical properties
Physical properties: electrical, thermic and magnetic behaviors
Degradation and stability
Corrosion/oxidation

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Published Papers (14 papers)

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Editorial

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3 pages, 182 KiB

Open AccessEditorial

News Trends in Powder Metallurgy: Microstructures, Properties, Durability

by Eric Hug and Guy Dirras

Metals 2021, 11(8), 1216; https://doi.org/10.3390/met11081216 - 30 Jul 2021

Cited by 1 | Viewed by 1685

Abstract

Compared with traditional casting or plastic deformation processes, powder metallurgy-based methods are versatile routes for producing in-demand microstructures of various types [...] Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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12 pages, 4518 KiB

Open AccessArticle

Ratcheting-Fatigue Behavior of Harmonic-Structure-Designed SUS316L Stainless Steel

by Yang Song, Zhe Zhang, Hantuo Ma, Masashi Nakatani, Mie Ota Kawabata and Kei Ameyama

Metals 2021, 11(3), 477; https://doi.org/10.3390/met11030477 - 13 Mar 2021

Cited by 5 | Viewed by 2528

Abstract

Stainless steels with harmonic-structure design have a great balance of high strength and high ductility. Therefore, it is imperative to investigate their fatigue properties for engineering applications. In the present work, the harmonic-structured SUS316L stainless steels were fabricated by mechanical milling (MM) and subsequent hot isostatic pressing (HIP) process. A series of ratcheting-fatigue tests were performed on the harmonic-structured SUS316L steels under stress-control mode at room temperature. Effects of grain structure and stress-loading conditions on ratcheting behavior and fatigue life were investigated. Results showed that grain size and applied mean stress had a significant influence on ratcheting-strain accumulation and fatigue life. Owing to the ultrafine grained structure, tensile strength of the harmonic-structured SUS316L steels could be enhanced, which restrained the ratcheting-strain accumulation, resulting in a prolonged fatigue life. A higher mean stress caused a faster ratcheting-strain accumulation, which led to the deterioration of fatigue life. Moreover, a modified model based on Smith–Watson–Topper (SWT) criterion predicted the ratcheting-fatigue life of the harmonic-structured SUS316L steels well. Most of the fatigue-life points were located in the 5 times error band. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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13 pages, 3108 KiB

Open AccessArticle

Influence of Successive Chemical and Thermochemical Treatments on Surface Features of Ti6Al4V Samples Manufactured by SLM

by Jesús E. González, Gabriela de Armas, Jeidy Negrin, Ana M. Beltrán, Paloma Trueba, Francisco J. Gotor, Eduardo Peón and Yadir Torres

Metals 2021, 11(2), 313; https://doi.org/10.3390/met11020313 - 11 Feb 2021

Cited by 14 | Viewed by 3121

Abstract

Ti6Al4V samples, obtained by selective laser melting (SLM), were subjected to successive treatments: acid etching, chemical oxidation in hydrogen peroxide solution and thermochemical processing. The effect of temperature and time of acid etching on the surface roughness, morphology, topography and chemical and phase composition after the thermochemical treatment was studied. The surfaces were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and contact profilometry. The temperature used in the acid etching had a greater influence on the surface features of the samples than the time. Acid etching provided the original SLM surface with a new topography prior to oxidation and thermochemical treatments. A nanostructure was observed on the surfaces after the full process, both on their protrusions and pores previously formed during the acid etching. After the thermochemical treatment, the samples etched at 40 °C showed macrostructures with additional submicro and nanoscale topographies. When a temperature of 80 °C was used, the presence of micropores and a thicker anatase layer, detectable by X-ray diffraction, were also observed. These surfaces are expected to generate greater levels of bioactivity and high biomechanics fixation of implants as well as better resistance to fatigue. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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15 pages, 6355 KiB

Open AccessArticle

SHS Synthesis, SPS Densification and Mechanical Properties of Nanometric Tungsten

by Sarah Dine, Elodie Bernard, Nathalie Herlin, Christian Grisolia, David Tingaud and Dominique Vrel

Metals 2021, 11(2), 252; https://doi.org/10.3390/met11020252 - 2 Feb 2021

Cited by 4 | Viewed by 2232

Abstract

Recent studies have shown that low grain sizes are favorable to improve ductility and machinability in tungsten, as well as a resistance to ablation and spallation, which are key properties for the use of this material in a thermonuclear fusion environment (Tokamaks such as ITER). However, as one of the possible incidents during Tokamak operation is the leakage of air or water from the cooling system inside the chamber, resulting in the so-called loss of vacuum accident (LOVA), extensive oxidation may arise on tungsten components, and the use of an alloy with improved oxidation resistance is therefore highly desirable. As current production routes are not suitable for the fabrication of bulk nanostructured tungsten or tungsten alloys samples, we have proposed a new methodology based on powder metallurgy, including the powder synthesis, the densification procedure, and preliminary mechanical testing, which was successfully applied to pure tungsten. A similar study is hereby presented on tungsten-chromium alloys with up to 6 wt.% Cr. Results show that full tungsten densification may be obtained by SPS at a temperature lower than 1600 °C. The resulting morphology strongly depends on the amount of the alloying element, presenting a possible second phase of chromium oxide, but always keeps a partial nanostructure inherited from the synthesized powders. Such microstructure had previously been identified as being favorable to the use of these materials in fusion environments and for improved mechanical properties, including hardness, yield strength and ductility, all of which is confirmed by the present study. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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16 pages, 4586 KiB

Open AccessArticle

Processing and Characterization of Bilayer Materials by Solid State Sintering for Orthopedic Applications

by Jorge Sergio Téllez-Martínez, Luis Olmos, Víctor Manuel Solorio-García, Héctor Javier Vergara-Hernández, Jorge Chávez and Dante Arteaga

Metals 2021, 11(2), 207; https://doi.org/10.3390/met11020207 - 23 Jan 2021

Cited by 2 | Viewed by 2027

Abstract

A new processing route is proposed to produce graded porous materials by placing particles of Ti6Al4V with different sizes in different configurations to obtain bilayer samples that can be used as bone implants. The sintering behavior is studied by dilatometry and the effect of the layers’ configuration is established. To determine pore features, SEM and computed microtomography were used. Permeability is evaluated by numerical simulations in the 3D real microstructures and the mechanical properties are evaluated by compression tests. The results show that a graded porosity is obtained as a function of the size of the particle used. The mechanical anisotropy due to the pore size distribution and the sintering kinetics, can be changed by the particle layer arrangements. The Young modulus and yield stress depend on the relative density of the samples and can be roughly predicted by a power law, considering the layers’ configuration on the compression behavior. Permeability is intimately related to the median pore size that leads to anisotropy due to the layers’ configuration with smaller and coarser particles. It is concluded that the proposed processing route can produce materials with specific and graded characteristics, with the radial configuration being the most promising for biomedical applications. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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18 pages, 5275 KiB

Open AccessArticle

Exploring the Strain Hardening Mechanisms of Ultrafine Grained Nickel Processed by Spark Plasma Sintering

by Lucía García de la Cruz, Mayerling Martinez Celis, Clément Keller and Eric Hug

Metals 2021, 11(1), 65; https://doi.org/10.3390/met11010065 - 30 Dec 2020

Cited by 5 | Viewed by 2376

Abstract

Ultrafine grained (UFG) materials in the bigger grain size range (0.5–1) µm display a good combination of strength and ductility, unlike smaller size UFG and nanostructured metals, which usually exhibit high strength but low ductility. Such difference can be attributed to a change in plasticity mechanisms that modifies their strain hardening capability. The purpose of this work is to investigate the work hardening mechanisms of UFG nickel considering samples with grain sizes ranging from 0.82 to 25 µm. Specimens processed combining ball milling and spark plasma sintering were subjected to monotonous tensile testing up to fracture. Then, microstructural observations of the deformed state of the samples were carried out by electron backscattered diffraction and transmission electron microscopy. A lower strain hardening capability is observed with decreasing grain size. Samples in the submicrometric range display the three characteristic stages of strain hardening with a short second stage and the third stage beginning soon after yielding. Microstructural observations display a low fraction of low angle grain boundaries and dislocation density for the sample with d = 0.82 µm, suggesting changes in plasticity mechanisms early in the UFG range. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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19 pages, 6384 KiB

Open AccessArticle

Powder Metallurgy Processing and Mechanical Properties of Controlled Ti-24Nb-4Zr-8Sn Heterogeneous Microstructures

by Benoît Fer, David Tingaud, Azziz Hocini, Yulin Hao, Eric Leroy, Frédéric Prima and Guy Dirras

Metals 2020, 10(12), 1626; https://doi.org/10.3390/met10121626 - 4 Dec 2020

Cited by 8 | Viewed by 2905

Abstract

This paper gives some insights into the fabrication process of a heterogeneous structured β-metastable type Ti-24Nb-4Zr-8Sn alloy, and the associated mechanical properties optimization of this biocompatible and low elastic modulus material. The powder metallurgy processing route includes both low energy mechanical ball milling (BM) of spherical and pre-alloyed powder particles and their densification by Spark Plasma Sintering (SPS). It results in a heterogeneous microstructure which is composed of a homogeneous 3D network of β coarse grain regions called “core” and α/β dual phase ultra-fine grain regions called “shell.” However, it is possible to significantly modify the microstructural features of the alloy—including α phase and shell volume fractions—by playing with the main fabrication parameters. A focus on the role of the ball milling time is first presented and discussed. Then, the mechanical behavior via shear tests performed on selected microstructures is described and discussed in relation to the microstructure and the probable underlying deformation mechanism(s). Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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10 pages, 4915 KiB

Open AccessFeature PaperArticle

Joining of Oxide Dispersion-Strengthened Steel Using Spark Plasma Sintering

by Foad Naimi, Jean-Claude Niepce, Mostapha Ariane, Cyril Cayron, José Calapez, Jean-Marie Gentzbittel and Frédéric Bernard

Metals 2020, 10(8), 1040; https://doi.org/10.3390/met10081040 - 2 Aug 2020

Cited by 3 | Viewed by 2849

Abstract

Difficulties with joining oxide dispersion-strengthened (ODS) steels using classical welding processes have led to the development of alternative joining techniques such as spark plasma sintering (SPS). SPS, which is classically employed for performing sintering, may also be used to join relatively large components due to the simultaneous application of electrical pulsed current and uniaxial charge. SPS technology was tested by joining two ODS steel disks. The preliminary tests showed that it is necessary to control surface roughness before joining. Furthermore, the use of ground and lapped surfaces seemed to improve the quality of the interface. Tensile tests on two ODS cylinders joined using SPS were performed at 750 °C without any additives. Failure occurred away from the interface with a total elongation close to 50% and an ultimate stress of 110 MPa. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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17 pages, 23464 KiB

Open AccessArticle

Influence of Carbon Diffusion and the Presence of Oxygen on the Microstructure of Molybdenum Powders Densified by SPS

by Mathias Moser, Sylvain Lorand, Florian Bussiere, Frédéric Demoisson, Hervé Couque and Frédéric Bernard

Metals 2020, 10(7), 948; https://doi.org/10.3390/met10070948 - 14 Jul 2020

Cited by 6 | Viewed by 3210

Abstract

Due to molybdenum’s Body-Centered Cubic (BCC) crystalline structure, its ductile–brittle transition temperature is sensitive to shaping, purity and microstructure. Dense molybdenum parts are usually shaped by the powder metallurgy process. The aim of this work concerns the spark plasma sintering of high-purity powders prepared by inductively coupled plasma. The influence of carbon diffusion and its interaction with oxygen on the density (i.e., the densification stage) and on the microstructure (i.e., the grain growth stage) during spark plasma sintering was investigated. The formation of carbide is usually expected for a sintering temperature above 1500 °C leading to grain growth (e.g., more than 10 times larger than the initial powder grain size after sintering at 1900 °C for 10 min). The brittleness was also affected by the segregation of molybdenum carbides at the grain boundaries (i.e., intergranular brittle fracture). Consequently, to reduce the sintering temperature to below 1500 °C, mechanically activated powders were used. From these milled powders, a dense molybdenum disc (60 mm in diameter and 10 mm in thickness) sintered at 1450 °C under a pressure of 70 MPa for 30 min was obtained. It is composed of a fine microstructure without carbide and oxide, its ductility is close to 13% with a maximum resistance of 550 MPa. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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22 pages, 5494 KiB

Open AccessArticle

Investigation on the Durability of Ti-6Al-4V Alloy Designed in a Harmonic Structure via Powder Metallurgy: Fatigue Behavior and Specimen Size Parameter Issue

by Benjamin Guennec, Takayuki Ishiguri, Mie Ota Kawabata, Shoichi Kikuchi, Akira Ueno and Kei Ameyama

Metals 2020, 10(5), 636; https://doi.org/10.3390/met10050636 - 14 May 2020

Cited by 10 | Viewed by 2929

Abstract

In the present work, the four-point bending loading fatigue properties of a heterogeneously distributed grain size microstructure consolidated from Ti-6Al-4V alloy powder are studied. The microstructure involved here, a so-called “harmonic structure”, possesses quasi-spherical large grain regions (“cores”) embedded in a continuous fine grain region (“shell”). Unlike the previous reports dealing with this issue, the effect of the specimen size on the fatigue characteristics is also probed, since two distinct specimen configurations are considered. Furthermore, the obtained experimental data are compared with the corresponding fatigue results derived from homogeneous coarse grain counterparts. Contrary to homogeneous structure material, discrepancies on both the fatigue strength and the fatigue crack initiation aspects are found for the harmonic structure material. Consequently, the present work aims to clarify the underlining phenomena involved in the specimen size effect detected for Ti-6Al-4V designed in the harmonic structure. A less active interface surface between the core and the shell combined with a wider critical volume in the large size specimen should be the main reasons of the fatigue strength discrepancy. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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17 pages, 2118 KiB

Open AccessArticle

Spark Plasma Sintering as an Effective Texturing Tool for Reprocessing Recycled HDDR Nd-Fe-B Magnets with Lossless Coercivity

by Awais Ikram, Muhammad Awais, Richard Sheridan, Allan Walton, Spomenka Kobe, Franci Pušavec and Kristina Žužek Rožman

Metals 2020, 10(3), 418; https://doi.org/10.3390/met10030418 - 24 Mar 2020

Cited by 6 | Viewed by 3841

Abstract

The low-pressure hot-deformation methodology was applied to reprocess the nanocrystalline hydrogenation–disproportionation–desorption–recombination (HDDR) Nd-Fe-B powders from end-of-life (EOL) permanent magnets’ waste to determine the mechanism of texture development and the resultant improvement in remanence (and BH_max) in the recycled material. Both the hot-pressed and hot-deformed magnets produced via spark plasma sintering (SPS) were compared in terms of their magnetic properties with respect to forging pressures. Also, a comparison was established with the microstructure to cite the effectiveness of texture development at low deformation rates and pressures which is pivotal for retaining high coercivity. The hot-pressed magnets maintain the high coercivity (better than 100%) of the original recycled powder due to the control of SPS conditions. The hot deformation pressure was varied from 100–150 MPa at 750 °C processing temperature to identify the optimal texture development in the sintered HDDR Nd-Fe-B magnets. The effect of post-hot-deformation thermal treatment was also investigated, which helped in boosting the overall magnetic properties and better than the recycled feedstock. This low-pressure hot deformation process improved the remanence of the hot-pressed magnet by 11% over the starting recycled powder. The M_r/M_S ratio which was 0.5 for the hot-pressed magnets increased to 0.64 for the magnets hot-deformed at 150 MPa. Also, a 55% reduction in height of the sample was achieved with the c-axis texture, indicating approximately 23% higher remanence over the isotropic hot-pressed magnets. After hot deformation, the intrinsic coercivity (H_Ci) of 960 kA/m and the remanence (B_r) value of 1.01 T at 150 MPa is indicative that the controlled SPS reprocessing technique can prevent microstructure related losses in the magnetic properties of the recycled materials. This route also suggests that the scrap Nd-Fe-B magnets can be treated with recoverable magnetic properties subsequently via HDDR technique and controlled hot deformation with a follow-up annealing. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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20 pages, 6981 KiB

Open AccessFeature PaperReview

Elaboration of Metallic Materials by SPS: Processing, Microstructures, Properties, and Shaping

by Jean-Philippe Monchoux, Alain Couret, Lise Durand, Thomas Voisin, Zofia Trzaska and Marc Thomas

Metals 2021, 11(2), 322; https://doi.org/10.3390/met11020322 - 12 Feb 2021

Cited by 23 | Viewed by 3721

Abstract

After a few decades of increasing interest, spark plasma sintering (SPS) has now become a mature powder metallurgy technique, which allows assessing its performances toward fabricating enhanced materials. Here, the case of metals and alloys will be presented. The main advantage of SPS lies in its rapid heating capability enabled by the application of high intensity electric currents to a metallic powder. This presents numerous advantages balanced by some limitations that will be addressed in this review. The first section will be devoted to sintering issues, with an emphasis on the effect of the electric current on the densification mechanisms. Then, typical as-SPS microstructures and properties will be presented. In some cases, they will be compared with that of materials processed by conventional techniques. As such, examples of nanostructured materials, intermetallics, metallic glasses, and high entropy alloys, will be presented. Finally, the implementation of SPS as a technique to manufacture complex, near-net shape industrial parts will be discussed. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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16 pages, 9789 KiB

Open AccessReview

Harmonic Structure Design: A Strategy for Outstanding Mechanical Properties in Structural Materials

by Bhupendra Sharma, Guy Dirras and Kei Ameyama

Metals 2020, 10(12), 1615; https://doi.org/10.3390/met10121615 - 1 Dec 2020

Cited by 20 | Viewed by 4276

Abstract

Structured heterogeneous materials are ubiquitous in a biological system and are now adopted in structural engineering to achieve tailor-made properties in metallic materials. The present paper is an overview of the unique network type heterogeneous structure called Harmonic Structure (HS) consisting of a continuous three-dimensional network of strong ultrafine-grained (shell) skeleton filled with islands of soft coarse-grained (core) zones. The HS microstructure is realized by the strategic processing method involving severe plastic deformation (SPD) of micron-sized metallic powder particles and their subsequent sintering. The microstructure and properties of HS-designed materials can be controlled by altering a fraction of core and shell zones by controlling mechanical milling and sintering conditions depending on the inherent characteristics of a material. The HS-designed metallic materials exhibit an exceptional combination of high strength and ductility, resulting from optimized hierarchical features in the microstructure matrix. The experimental and numerical results demonstrate that the continuous network of gradient structure in addition to the large degree of microstructural heterogeneity leads to obvious mechanical incompatibility and strain partitioning, during plastic deformation. Therefore, in contrast to the conventional homogeneous (homo) structured materials, synergy effects, such as synergy strengthening, can be obtained in HS-designed materials. This review highlights recent developments in HS-structured materials as well as identifies further challenges and opportunities. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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23 pages, 7293 KiB

Open AccessReview

Spark Plasma Sintering of Titanium Aluminides: A Progress Review on Processing, Structure-Property Relations, Alloy Development and Challenges

by Ntebogeng F. Mogale and Wallace R. Matizamhuka

Metals 2020, 10(8), 1080; https://doi.org/10.3390/met10081080 - 11 Aug 2020

Cited by 26 | Viewed by 5396

Abstract

Titanium aluminides (TiAl) have the potential of substituting nickel-based superalloys (NBSAs) in the aerospace industries owing to their lightweight, good mechanical and oxidation properties. Functional simplicity, control of sintering parameters, exceptional sintering speeds, high reproducibility, consistency and safety are the main benefits of spark plasma sintering (SPS) over conventional methods. Though TiAl exhibit excellent high temperature properties, SPS has been employed to improve on the poor ductility at room temperature. Powder metallurgical processing techniques used to promote the formation of refined, homogeneous and contaminant-free structures, favouring improvements in ductility and other properties are discussed. This article further reviews published work on phase constituents, microstructures, alloy developments and mechanical properties of TiAl alloys produced by SPS. Finally, an overview of challenges in as far as the implementation of TiAl in industries of interest are highlighted. Full article

(This article belongs to the Special Issue News Trends in Powder Metallurgy: Microstructures, Properties, Durability)

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