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Crystals
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Thermomechanical Processing and Microstructure Control of Ti Alloys
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Thermomechanical Processing and Microstructure Control of Ti Alloys

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Metals and Alloys".

Deadline for manuscript submissions: closed (15 May 2021) | Viewed by 8599

Special Issue Editors

Prof. Dr. Katsuyoshi Kondoh

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Guest Editor
Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
Interests: composite materials processing; Al, Mg and Ti alloys
Dr. Abdollah Bahador

E-Mail Website
Guest Editor
Razak Faculty of Technology and Informatics, Universiti Teknologi Malaysia, Kuala Lumpur 54100, Malaysia
Interests: Ti alloys; non-ferrous metals; metal matrix composite; shape memory alloys; powder metallurgy; welding and joining
Dr. Ridvan Yamanoglu

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Guest Editor
Kocaeli University, Engineering Faculty, Metallurgical and Materials Engineering Department, Kocaeli, Turkey
Interests: powder metallurgy; sintering; composite; titanium; hot pressing; spark plasma sintering

Special Issue Information

Dear Colleagues,

Ti alloys offer a wide range of properties such as excellent corrosion resistance and biocompatibility, high specific strength, and high-temperature strength, which are facilitated by proper control of microstructures. These properties are unique advantages for titanium alloys to be used in various engineering fields, such as the aerospace, biomedical, automotive, and oil and gas industries. Ti has an allotropic nature which provides an opportunity to be processed with diverse phases and crystallographic structures. Enhanced mechanical properties are attributed to the tailoring microstructure, constituent phases, grain refinement, and crystallographic texture, which can be imparted by thermomechanical treatments, including severe cold/hot plastic deformation, solution treatment, and recrystallization. Significant progress has been made over the last few decades in developing high-strength Ti alloys at both room temperature and elevated temperatures via solid solution and particulate reinforcement; however, further improvement in the mechanical properties of Ti alloys is still needed. This Special Issue of Crystals aims to present recent original research on the microstructure and mechanical properties of Ti alloys. The scope includes detailed microstructure characterization and its correlation with improved mechanical properties, including but not limited to tensile and compression strength, ductility, creep resistance, and fracture toughness.

Prof. Katsuyoshi Kondoh
Dr. Abdollah Bahador
Dr. Ridvan Yamanoglu
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. Crystals 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

  • Thermomechanical treatments
  • Microstructure control
  • Mechanical properties
  • Plastic deformation
  • Solid solution
  • Particulate strengthening
  • Crystal orientation

Published Papers (4 papers)

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Research

13 pages, 8459 KiB  
Article
Precipitation and Distribution Behavior of In Situ-Formed TiB Whiskers in Ti64 Composites Fabricated by Selective Laser Melting
by Junko Umeda, Lei Jia, Biao Chen, Ke Chen, Shufeng Li, Kazuki Shitara and Katsuyoshi Kondoh
Crystals 2021, 11(4), 374; https://doi.org/10.3390/cryst11040374 - 03 Apr 2021
Cited by 4 | Viewed by 1983
Abstract
The precipitation and distribution behaviors of in situ-formed titanium boride whiskers (TiB) in TiBw-reinforced Ti-6%Al-4%V (Ti64) composites fabricated from an elemental mixture of Ti64 alloy powder and TiB2 particles by selective laser melting were investigated. The primary precipitation of TiB whiskers strongly [...] Read more.
The precipitation and distribution behaviors of in situ-formed titanium boride whiskers (TiB) in TiBw-reinforced Ti-6%Al-4%V (Ti64) composites fabricated from an elemental mixture of Ti64 alloy powder and TiB2 particles by selective laser melting were investigated. The primary precipitation of TiB whiskers strongly depends on B content. For a B content of less than 2 mass%, when the liquid → β-phase transformation occurred and B atoms were discharged, the B-enriched area formed around the β-phase resulted in the generation of TiB whiskers and their agglomeration at the prior β-grain boundaries. When the B content was over 2 mass%, TiB whiskers directly precipitated from the liquid phase and moved to the molten pool boundary via Marangoni convection. As a result, the TiB whiskers were located along the boundary. Furthermore, B-enrichment caused a decrease in the liquidus temperature and thus obstructed β-grain coarsening, and as a result, fine equiaxed α’-grains formed during the phase transformation. Full article
(This article belongs to the Special Issue Thermomechanical Processing and Microstructure Control of Ti Alloys)
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12 pages, 27874 KiB  
Article
Effect of Metal Powder Characteristics on Structural Defects of Graphene Nanosheets in Metal Composite Powders Dispersed by Ball Milling
by Qi Yan, Biao Chen, Xinyi Zhou, Katsuyoshi Kondoh and Jinshan Li
Crystals 2021, 11(3), 260; https://doi.org/10.3390/cryst11030260 - 06 Mar 2021
Cited by 2 | Viewed by 2141
Abstract
Ball milling (BM) is the prime method to disperse graphene into metal powders; however, it inevitably introduces structural defects to graphene. The balance between dispersion quality and structural damage of graphene during BM is a significant issue for fabricating graphene/metal composite powders. In [...] Read more.
Ball milling (BM) is the prime method to disperse graphene into metal powders; however, it inevitably introduces structural defects to graphene. The balance between dispersion quality and structural damage of graphene during BM is a significant issue for fabricating graphene/metal composite powders. In this study two metal powder characteristics, namely type and size, were investigated to understand the effect of the BM process on graphene structure in graphene/metal composite powders. Graphene nanosheets (GNSs) were added into commercial Ti-6Al-4V and pure Al powders with different diameters by three kinds of BM processes with distinct energy levels. According to the microstructure and Raman spectra, the results suggested that metal particle size had a minor influence in low-energy BM, while it played an important role in high-energy BM (HEBM). The structural defects of GNS crystals increase with increasing BM energy. However, increasing energy in BM has limited damage as the discrepancy in particle size is quite large. Furthermore, Al powders with lower hardness tend to deform with lower BM effect, which will cause less damage to GNSs compared to that in the harder Ti powder. Those findings may have implications for the development of high-performance metal matrix composites reinforced with nanocarbon materials. Full article
(This article belongs to the Special Issue Thermomechanical Processing and Microstructure Control of Ti Alloys)
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9 pages, 10221 KiB  
Article
The Effect of Heat Treatment on Dynamic Properties of an Additively Manufactured Ti-6Al-4V Alloy
by Shuangyin Zhang, Yunfei Wang, Tao Suo, Jin Yao, Xin Lin, Weidong Huang, Yulong Li and Jianghua Shen
Crystals 2021, 11(2), 111; https://doi.org/10.3390/cryst11020111 - 26 Jan 2021
Cited by 2 | Viewed by 1575
Abstract
Heat treatment processing is commonly applied for additively manufactured metal materials, since the as-fabricated material frequently exhibits high internal stress and self-cracking. In this work, a heat treatment route was applied to an additively manufactured Ti-6Al-4V alloy, and its effect on the dynamic [...] Read more.
Heat treatment processing is commonly applied for additively manufactured metal materials, since the as-fabricated material frequently exhibits high internal stress and self-cracking. In this work, a heat treatment route was applied to an additively manufactured Ti-6Al-4V alloy, and its effect on the dynamic compressive behavior was investigated. The experimental results showed that the heat treatment process not only increased the dynamic compressive strength of the material, but also induced a change of the dynamic compressive strength from isotropic to anisotropic. In addition, the strain rate sensitivity of the material was reduced by heat treatment, even though both the as-deposited and heat-treated samples demonstrated positive sensitivity to the loading rate. Microstructural analysis suggested that the grain size and morphology were the same before and after heat treatment, while the internal stress increased due to heat treatment. Full article
(This article belongs to the Special Issue Thermomechanical Processing and Microstructure Control of Ti Alloys)
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7 pages, 4289 KiB  
Article
Microstructure and Material Properties of Ti-15mass%Nb Alloy after Gas Nitriding and Quenching Process
by Yoshikazu Mantani, Kentaro Shimada and Naoki Eguchi
Crystals 2020, 10(12), 1156; https://doi.org/10.3390/cryst10121156 - 18 Dec 2020
Viewed by 2195
Abstract
The α′ martensite of Ti-15mass%Nb alloy exhibits high internal friction with high damping properties. However, its structure is smoother than the α + β structure. Therefore, a hardened surface layer is required for abrasion resistance. This study fabricated a martensite structure inside the [...] Read more.
The α′ martensite of Ti-15mass%Nb alloy exhibits high internal friction with high damping properties. However, its structure is smoother than the α + β structure. Therefore, a hardened surface layer is required for abrasion resistance. This study fabricated a martensite structure inside the nitriding layer by quenching, after gas nitriding at 1023 and 1223 K. Vickers hardness test, X-ray diffraction, scanning electron microscopy (SEM), and SEM-energy dispersive X-ray (SEM-EDX) measurements from the surface to the inside were made after the heat treatment process. In addition, the Young’s modulus and internal friction were calculated from the damping analysis. The α-TiN0.3 and β phase region was formed at approximately 80 µm from the surface at 1023 and 1223 K, and it was hardened. The internal friction of the gas nitriding and quenching specimens at 1023 and 1223 K was relatively high, though it did not reach that of the as-quenched specimen owing to the influence of the surface structure. From these results, it is considered that these material property values of the alloy can be controlled using the nitriding and quenching processes. Full article
(This article belongs to the Special Issue Thermomechanical Processing and Microstructure Control of Ti Alloys)
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