Special Issue "Advanced Mechanical Testing of Powder Metallurgy Alloys"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 May 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Paul Bishop

Mechanical Engineering, Dalhousie University, PO Box 15000, Halifax, NC B3H 4R2, Canada
Website | E-Mail
Interests: powder metallurgy processing of light metals; alloy development; mechanical testing; powder forging

Special Issue Information

Dear Colleagues,

The development of advanced powder metallurgy materials and processing technologies has been a central pillar of innovation within the global PM community for decades.  Indeed, the outcomes of these endeavors have underpinned a prolific expansion in the scope of commercial end-use applications. As many of these represent new and exciting areas, conventional mechanical property data, such as hardness and static tensile testing no longer suffice and a heightened need for advanced mechanical property data has frequently emerged.  With this in mind, and your stature as a prolific researcher in this field, I cordially invite you to submit an original manuscript on advanced mechanical testing of powder metallurgy materials to be published as part of a Special Issue in the journal Metals. Focal areas of interest include (but are not limited to) dynamic mechanical testing (fatigue, impact, fracture toughness, etc.), thermal mechanical testing, tribological testing, impulse excitation testing, and elevated temperature testing accompanied by microstructural and/or thermal analyses so as to instill a comprehensive understanding of the observed mechanical behaviour. Ferrous and non-ferrous alloys are both of interest, as well as metal matrix composites made thereof.

Prof. Dr. Paul Bishop
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. 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 1200 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 Alloys
  • Advanced Mechanical Testing
  • Material Characterization
  • Ferrous alloys
  • Non-ferrous Alloys

Published Papers (4 papers)

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Research

Open AccessArticle A Hot Extrusion Process without Sintering by Applying MWCNTs/Al6061 Composites
Metals 2018, 8(3), 184; https://doi.org/10.3390/met8030184
Received: 16 January 2018 / Revised: 16 February 2018 / Accepted: 6 March 2018 / Published: 14 March 2018
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Abstract
For carbon nanotube (CNT)/Al composites, compaction forming is conducted for densification processing, and then sintering and secondary processes are conducted. This general process has problems such as the complexity of the processing procedures, and high manufacturing costs. This study presents a hot extrusion
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For carbon nanotube (CNT)/Al composites, compaction forming is conducted for densification processing, and then sintering and secondary processes are conducted. This general process has problems such as the complexity of the processing procedures, and high manufacturing costs. This study presents a hot extrusion process without sintering for fabrication of CNTs/Al6061 composites. Before hot extrusion, preforms are fabricated by the compaction process for the mixture of Al6061 power and CNTs. Several hot extrusion experiments were performed under six types of CNT content; three extrusion ratios and three extrusion temperatures. The formability increased as the extrusion temperature increased for low CNT content. At 620 °C, the forming of all materials except for 10 vol % CNTs/Al6061 was possible at extrusion ratios R = 4, R = 8, and R = 16. As CNT content increases, extrusion pressure almost linearly increases. As the extrusion ratio increases, the extrusion pressure increases. The amount of CNT content increases as Vickers hardness increases. The Vicker’s hardness of 1 vol % CNTs/Al6061 billet is about 100 HV while that of 10 vol % CNTs/Al6061 billet is about 230 HV. There are no significant differences of compression stress according to extrusion ratio as observed in terms of pure Al6061, 1 vol % CNT/Al6061, and 3 vol % CNTs/Al6061. Full article
(This article belongs to the Special Issue Advanced Mechanical Testing of Powder Metallurgy Alloys)
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Figure 1

Open AccessArticle Dependence of Creep Performance and Microstructure Evolution on Solution Cooling Rate in a Polycrystalline Superalloy
Received: 30 November 2017 / Revised: 16 December 2017 / Accepted: 19 December 2017 / Published: 22 December 2017
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Abstract
It is well known that the solution cooling rate has a great effect on the creep life of superalloys. In this research, three typical cooling rates were applied to generate different distributions of γ’ precipitates for creep tests. Ingots used to make specimens
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It is well known that the solution cooling rate has a great effect on the creep life of superalloys. In this research, three typical cooling rates were applied to generate different distributions of γ’ precipitates for creep tests. Ingots used to make specimens were manufactured by hot extrusion, and the master alloy had the composition of an FGH4096 power metallurgy superalloy. SEM and SESD were used to observe the microstructure’s evolution. The experimental results show that the fastest cooling rate corresponds to the highest creep life as well as the smallest rupture strain, and vice versa. The microscopic observations disclose that with an increasing cooling rate, the size and area fraction of γ’ precipitates decrease, and the rupture mechanism changes from transgranular to intergranular. Moreover, some γ’ precipitates changed to cuboid after the creep test. The results will provide new technological processes to design more creep-resistant, nickel-base superalloys. Full article
(This article belongs to the Special Issue Advanced Mechanical Testing of Powder Metallurgy Alloys)
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Open AccessArticle Effect of Compression Process of MWCNT-Reinforced Al6061 Powder on Densification Characteristics and Its Mechanical Properties
Metals 2017, 7(10), 437; https://doi.org/10.3390/met7100437
Received: 13 July 2017 / Revised: 26 September 2017 / Accepted: 10 October 2017 / Published: 18 October 2017
Cited by 2 | PDF Full-text (9552 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, aluminium-based (Al6061) composites with 1, 3, 5, 7, and 10 vol % of multi-walled carbon nanotubes (MWCNTs) are investigated. The composites are fabricated by high-energy ball milling, cold-compacting at room temperature under compacting pressures of 400–1600 MPa, and sintering at
[...] Read more.
In this paper, aluminium-based (Al6061) composites with 1, 3, 5, 7, and 10 vol % of multi-walled carbon nanotubes (MWCNTs) are investigated. The composites are fabricated by high-energy ball milling, cold-compacting at room temperature under compacting pressures of 400–1600 MPa, and sintering at 620 °C in an argon gas atmosphere. Thereafter, the hardness and microstructure of MWCNTs/Al6061 composites are examined. Further, to improve the relative density and hardness level of the complex material, open-die forging is performed after cold-compacting under 1 GPa pressure at room temperature and sintering at 620 °C. The open-die forging parameters include 1, 3, 5, 7, and 10 vol % MWCNTs/Al6061, and Al6061. The experimental results show that the mechanical properties of the composites are significantly superior to that of the Al6061 alloy after undergoing cold-compacting, sintering, and open-die forging. Full article
(This article belongs to the Special Issue Advanced Mechanical Testing of Powder Metallurgy Alloys)
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Open AccessFeature PaperArticle Effects of Post-Sinter Processing on an Al–Zn–Mg–Cu Powder Metallurgy Alloy
Metals 2017, 7(9), 370; https://doi.org/10.3390/met7090370
Received: 16 August 2017 / Revised: 7 September 2017 / Accepted: 8 September 2017 / Published: 13 September 2017
Cited by 1 | PDF Full-text (6551 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this work was to study the effects of several post-sinter processing operations (heat-treatment, sizing, shot peening) on a press-and-sinter 7xxx series aluminum powder metallurgy (PM) alloy. The characterization of the products was completed through a combination of non-contact surface profiling,
[...] Read more.
The objective of this work was to study the effects of several post-sinter processing operations (heat-treatment, sizing, shot peening) on a press-and-sinter 7xxx series aluminum powder metallurgy (PM) alloy. The characterization of the products was completed through a combination of non-contact surface profiling, hardness measurements, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X-ray diffraction (XRD), tensile, and three-point bend fatigue testing. It was determined that sizing in the as-quenched state imparted appreciable reductions in surface hardness (78 HRB) and fatigue strength (168 MPa) relative to counterpart specimens that were sized prior to solutionizing (85 HRB and 228 MPa). These declines in performance were ascribed to the annihilation of quenched in vacancies that subsequently altered the nature of precipitates within the finished product. The system responded well to shot peening, as this process increased fatigue strength to 294 MPa. However, thermal exposure at 353 K (80 °C) and 433 K (160 °C) then reduced fatigue performance to 260 MPa and 173 MPa, respectively, as a result of residual stress relaxation and in-situ over-aging. Full article
(This article belongs to the Special Issue Advanced Mechanical Testing of Powder Metallurgy Alloys)
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