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2 pages, 176 KiB

Open AccessEditorial

New Insights of Powder Metallurgy: Microstructure, Durability and Properties

by Jaroslav Kováčik and Anchalee Manonukul

Materials 2023, 16(6), 2307; https://doi.org/10.3390/ma16062307 - 13 Mar 2023

Cited by 1 | Viewed by 889

Abstract

This Special Issue of Materials, entitled “New Insight of Powder Metallurgy: Microstructure, Durability and Properties”, aimed to publish original and review papers on new scientific and applied research making significant contributions to our findings and understanding of the current developments and trends [...] Read more.

This Special Issue of Materials, entitled “New Insight of Powder Metallurgy: Microstructure, Durability and Properties”, aimed to publish original and review papers on new scientific and applied research making significant contributions to our findings and understanding of the current developments and trends in powder metallurgy (PM) [...] Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

Research

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17 pages, 8231 KiB

Open AccessArticle

Microstructural and Tribological Characteristics of Composites Obtained by Detonation Spraying of Iron-Based Alloy—Carbide Powder Mixtures

by Fardad Azarmi and Xiangqing W. Tangpong

Materials 2023, 16(19), 6422; https://doi.org/10.3390/ma16196422 - 27 Sep 2023

Viewed by 608

Abstract

iron-based coatings have exhibited good mechanical properties, such as high hardness and good wear resistance, which are desirable properties in applications such as automobile brake rotors. iron-based coatings are also good replacements for Co- and Ni-based coatings, which are costly and could have [...] Read more.

iron-based coatings have exhibited good mechanical properties, such as high hardness and good wear resistance, which are desirable properties in applications such as automobile brake rotors. iron-based coatings are also good replacements for Co- and Ni-based coatings, which are costly and could have health and environmental concerns due to their toxicity. In this research, three different iron-based coatings were deposited using the Detonation Gun Spraying (DGS) technology onto aluminum substrates, including the steel powders alone (unreinforced), and steel powders mixed with Fe₃C and SiC particles, respectively. The microstructural characteristics of these coatings and mechanical properties, such as hardness and wear resistance, were examined. The morphology and structure of the feedstock powders were affected by the exposure to high temperature during the spraying process and rapid solidification of steel powders that resulted in the formation of an amorphous structure. While it was expected that steel particles reinforced with hard ceramic particles would result in increased hardness, instead, the unreinforced steel coating had the highest hardness, possibly due to a higher degree of amorphization in the coating than the other two. The microstructural observation confirmed the formation of dense coatings with good adhesion between layers. All samples were subjected to ball-on-disk wear tests at room temperature (23 °C) and at 200 °C. Similar wear resistances of the three samples were obtained at room temperature. At 200 °C, however, both ceramic reinforced composite samples exhibited higher wear rates in line with the reduction in their hardness values. This work explains, from the microstructural point of view, why adding hard particles to steel powers may not always lead to coatings with higher hardness and better wear resistance. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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15 pages, 8075 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Low-Cost SiC-Reinforced Aluminum and Al4Cu Matrix Composites Produced by Sintering in Vacuum

by Anna Wąsik, Beata Leszczyńska-Madej, Marcin Madej and Marcin Goły

Materials 2023, 16(15), 5492; https://doi.org/10.3390/ma16155492 - 7 Aug 2023

Cited by 2 | Viewed by 974

Abstract

Composite materials based on Al and Al4Cu with the addition of SiC particles (2.5; 5; 7.5; 10 wt.%) were produced in low-cost conventional powder metallurgy processes involving mixing, compacting with a pressure of 300 MPa, and sintering at 600 °C in a vacuum [...] Read more.

Composite materials based on Al and Al4Cu with the addition of SiC particles (2.5; 5; 7.5; 10 wt.%) were produced in low-cost conventional powder metallurgy processes involving mixing, compacting with a pressure of 300 MPa, and sintering at 600 °C in a vacuum atmosphere. An attempt was made to create a relationship between the vacuum sintering and the microstructure and mechanical properties of Al/SiC composites. The strength of the matrix-reinforcing interface depends on the chemical composition of the components; therefore, the influence of 4 wt.% copper in the aluminum matrix was investigated. Comprehensive microstructural and mechanical properties (including Brinell hardness, compressive and flexural strength measurements) of the produced composites were measured. The addition of 2.5 wt.% SiC to the Al4Cu matrix improved the mechanical properties of the composites compared to the matrix. In the composite with the addition of 2.5 wt.% of SiC, while the addition of the reinforcement did not affect the hardness and compressive strength and caused a rapid decrease in the flexural strength compared to the aluminum matrix, the addition of Cu to the matrix of this composite improved hardness (from 25 to 49 HB), compressive strength (from 423 to 618 MPa), and flexural strength (from 52 to 355 MPa). Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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20 pages, 7872 KiB

Open AccessArticle

An Investigation into the Potential of Turning Induced Deformation Technique for Developing Porous Magnesium and Mg-SiO₂ Nanocomposite

by Michael Johanes and Manoj Gupta

Materials 2023, 16(6), 2463; https://doi.org/10.3390/ma16062463 - 20 Mar 2023

Cited by 2 | Viewed by 972

Abstract

A new and novel method of synthesising porous Mg materials has been explored utilising a variant of a processing method previously used for the synthesis of dense Mg materials, namely the turning-induced deformation (TID) method combined with sintering. It was found that the [...] Read more.

A new and novel method of synthesising porous Mg materials has been explored utilising a variant of a processing method previously used for the synthesis of dense Mg materials, namely the turning-induced deformation (TID) method combined with sintering. It was found that the Mg materials synthesised possessed comparable properties to previously-synthesised porous Mg materials in the literature while subsequent sintering resulted in a more consistent mechanical response, with microwave sintering showing the most promise. The materials were also found to possess mechanical response within the range of the human cancellous bone, and when reinforced with biocompatible silica nanoparticles, presented the most optimal combination of mechanical properties for potential use as biodegradable implants due to most similarity with cancellous bone properties. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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13 pages, 4586 KiB

Open AccessArticle

Application of U-FAST Technology in Sintering of Submicron WC-Co Carbides

by Joanna Wachowicz, Robert Kruzel, Zbigniew Bałaga, Agnieszka Ostrowska and Tomasz Dembiczak

Materials 2023, 16(6), 2450; https://doi.org/10.3390/ma16062450 - 19 Mar 2023

Cited by 2 | Viewed by 1121

Abstract

This article presents the microstructure, hardness, fracture toughness coefficient K_IC and phase composition of submicron WC-4Co carbides. The carbides were sintered using the innovative U-FAST (Upgraded Field Assisted Sintering Technology) method, from mixtures of WC-Co powders with an average WC grain size [...] Read more.

This article presents the microstructure, hardness, fracture toughness coefficient K_IC and phase composition of submicron WC-4Co carbides. The carbides were sintered using the innovative U-FAST (Upgraded Field Assisted Sintering Technology) method, from mixtures of WC-Co powders with an average WC grain size of 0.4 µm and 0.8 µm. The obtained sinters were characterized by a relative density above 99% of the theoretical density. The hardness of the obtained composites was above 2000 HV30, while the K_IC coefficient was about 8 MPa m^1/2. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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28 pages, 44738 KiB

Open AccessArticle

Influence of Microstructure on Fracture Mechanisms of the Heat-Treated AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion

by Gianluca Di Egidio, Carla Martini, Johan Börjesson, Ehsan Ghassemali, Lorella Ceschini and Alessandro Morri

Materials 2023, 16(5), 2006; https://doi.org/10.3390/ma16052006 - 28 Feb 2023

Cited by 11 | Viewed by 2161

Abstract

Few systematic studies on the correlation between alloy microstructure and mechanical failure of the AlSi10Mg alloy produced by laser-based powder bed fusion (L-PBF) are available in the literature. This work investigates the fracture mechanisms of the L-PBF AlSi10Mg alloy in as-built (AB) condition [...] Read more.

Few systematic studies on the correlation between alloy microstructure and mechanical failure of the AlSi10Mg alloy produced by laser-based powder bed fusion (L-PBF) are available in the literature. This work investigates the fracture mechanisms of the L-PBF AlSi10Mg alloy in as-built (AB) condition and after three different heat treatments (T5 (4 h at 160 °C), standard T6 (T6B) (1 h at 540 °C followed by 4 h at 160 °C), and rapid T6 (T6R) (10 min at 510 °C followed by 6 h at 160 °C)). In-situ tensile tests were conducted with scanning electron microscopy combined with electron backscattering diffraction. In all samples the crack nucleation was at defects. In AB and T5, the interconnected Si network fostered damage at low strain due to the formation of voids and the fragmentation of the Si phase. T6 heat treatment (T6B and T6R) formed a discrete globular Si morphology with less stress concentration, which delayed the void nucleation and growth in the Al matrix. The analysis empirically confirmed the higher ductility of the T6 microstructure than that of the AB and T5, highlighting the positive effects on the mechanical performance of the more homogeneous distribution of finer Si particles in T6R. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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18 pages, 8448 KiB

Open AccessArticle

Ni Porous Preforms Compacted with Al₂O₃ Particles and Al Binding Agent

by Andrej Opálek, Peter Švec, Matúš Žemlička, Matej Štěpánek, Pavol Štefánik, Stanislav Kúdela, Jr., Naďa Beronská and Karol Iždinský

Materials 2023, 16(3), 988; https://doi.org/10.3390/ma16030988 - 20 Jan 2023

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Abstract

This work presents an energy-efficient, cheap, and rapid production method of a metal–ceramic preform with open porosity suitable for liquid metal infiltration and filtration applications. It is based on cold isostatic pressing of a mixture of relatively hard Ni and Al₂O [...] Read more.

This work presents an energy-efficient, cheap, and rapid production method of a metal–ceramic preform with open porosity suitable for liquid metal infiltration and filtration applications. It is based on cold isostatic pressing of a mixture of relatively hard Ni and Al₂O₃ powders with the addition of small amount of Al powders, acting as a binding agent. Open porosity is primarily controlled by Al₂O₃ particles partially separating Ni particles from mutual contacts. Cold isostatic pressed green compacts were subjected to thermal oxidation by heating in air to 600 °C, 700 °C, and 800 °C. The weight gain and open porosity of oxidized compacts were examined. The chemical composition and microstructure were analyzed by SEM-EDS and XRD techniques. The stability of preforms and the effect of thermal cycling on the open porosity were tested by thermal cycling in an inert Ar atmosphere in the temperature range up to 800 °C. It appeared that, in addition to NiO being an expected product of oxidation, Ni aluminides and spinel particles also played an important role in inter-particle bonding formation. Ni-NiO porous composites resist chemical corrosion and exhibit structural and chemical stability at higher temperatures and admixed Al₂O₃ particles do not deteriorate them. After subsequent infiltration with Al, it can offer a lower density than other materials, which could result in lower energy consumption, which is highly needed in industries such as the automotive industry. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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21 pages, 11194 KiB

Open AccessArticle

Effects of Printing Layer Orientation on the High-Frequency Bending-Fatigue Life and Tensile Strength of Additively Manufactured 17-4 PH Stainless Steel

by Hamed Ghadimi, Arash P. Jirandehi, Saber Nemati, Huan Ding, Abdelrahman Garbie, Jonathan Raush, Congyuan Zeng and Shengmin Guo

Materials 2023, 16(2), 469; https://doi.org/10.3390/ma16020469 - 4 Jan 2023

Cited by 8 | Viewed by 1909

Abstract

In this paper, small blocks of 17-4 PH stainless steel were manufactured via extrusion-based bound powder extrusion (BPE)/atomic diffusion additive manufacturing (ADAM) technology in two different orientations. Ultrasonic bending-fatigue and uniaxial tensile tests were carried out on the test specimens prepared from the [...] Read more.

In this paper, small blocks of 17-4 PH stainless steel were manufactured via extrusion-based bound powder extrusion (BPE)/atomic diffusion additive manufacturing (ADAM) technology in two different orientations. Ultrasonic bending-fatigue and uniaxial tensile tests were carried out on the test specimens prepared from the AM blocks. Specifically, a recently-introduced small-size specimen design is employed to carry out time-efficient fatigue tests. Based on the results of the testing, the stress–life (S-N) curves were created in the very high-cycle fatigue (VHCF) regime. The effects of the printing orientation on the fatigue life and tensile strength were discussed, supported by fractography taken from the specimens’ fracture surfaces. The findings of the tensile test and the fatigue test revealed that vertically-oriented test specimens had lower ductility and a shorter fatigue life than their horizontally-oriented counterparts. The resulting S-N curves were also compared against existing data in the open literature. It is concluded that the large-sized pores (which originated from the extrusion process) along the track boundaries strongly affect the fatigue life and elongation of the AM parts. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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7 pages, 2369 KiB

Open AccessCommunication

The Room Temperature Fracture Behaviors of GNPs/TA15 Composites by Pre-Sintering and Hot Extrusion

by Jiabin Hou, Wencong Zhang, Guorong Cui, Wenzhen Chen, Xing Wang, Shuo Wu and Qiang Ma

Materials 2023, 16(1), 318; https://doi.org/10.3390/ma16010318 - 29 Dec 2022

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Abstract

Graphene nanoplates (GNPs)/TA15 composites were fabricated by pre-sintering and hot extrusion. During a room temperature tensile test, the dislocation was generated in grains. With increasing strain, the dislocation piled up along the interface between GNPs and Ti matrix, leading to stress concentration and [...] Read more.

Graphene nanoplates (GNPs)/TA15 composites were fabricated by pre-sintering and hot extrusion. During a room temperature tensile test, the dislocation was generated in grains. With increasing strain, the dislocation piled up along the interface between GNPs and Ti matrix, leading to stress concentration and microcracks. Then, the microcracks extended to GNPs or along the interface. The GNPs cracked under the shear force and the GNPs pulled out along with the crack propagation along the interface. This work provides a new sight in the room temperature tensile fracture behaviors. Full article

(This article belongs to the Special Issue New Insight of Powder Metallurgy: Microstructure, Durability and Mechanical Properties)

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