Metals

Research

Jump to: Review

15 pages, 6357 KiB

Open AccessArticle

Numerical Simulation of the Hot Isostatic Pressing Densification Behavior of Ti6Al4V Powder for a Thin-Walled Tubular Component with Non-Axisymmetric Inner Ribs

by Yanqing Jiang, Lin Geng and Guofeng Zhang

Metals 2025, 15(2), 173; https://doi.org/10.3390/met15020173 - 8 Feb 2025

Viewed by 692

Abstract

Hot isostatic pressing (HIP) technology is an efficient near-net-shape forming method to prepare complex-shaped structural components. However, for non-axisymmetric components with a complex shape, the powder flow and densification behaviors during HIP are still not clear, leading to a need for lots of [...] Read more.

Hot isostatic pressing (HIP) technology is an efficient near-net-shape forming method to prepare complex-shaped structural components. However, for non-axisymmetric components with a complex shape, the powder flow and densification behaviors during HIP are still not clear, leading to a need for lots of experiments to optimize the process parameters. In the current work, a typical aerospace thin-walled tubular component with non-axisymmetric inner ribs was selected as the research object, and its instantaneous powder flow and relative density during the whole HIP process were investigated by a numerical simulation method, focusing on the influence of HIP process conditions on powder densification. The simulation results indicate that the upper end of the Ti6Al4V thin-walled tubular part is preferentially densified, and the lowest densification is observed at the inner rib of the cylinder wall. Moreover, the effect on densification of each HIP condition, including sintering temperature (900–970 °C), pressure (120–180 MPa), and holding time (3–4 h), was evaluated separately. The HIP sintering temperature contributes the most to the improvement of densification, followed by the pressure, while the holding time contributes the least. Investigating HIP densification behavior is beneficial to the structural and process optimization of metal near-net-shape forming applications. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

22 pages, 6744 KiB

Open AccessArticle

Magnetic Pulse Powder Compaction

by Viktors Mironovs, Jekaterina Nikitina, Matthias Kolbe, Irina Boiko and Yulia Usherenko

Metals 2025, 15(2), 155; https://doi.org/10.3390/met15020155 - 4 Feb 2025

Viewed by 702

Abstract

Powder metallurgy (PM) offers several advantages over conventional melt metallurgy, including improved homogeneity, fine grain size, and pseudo-alloying capabilities. Transitioning from conventional methods to PM can result in significant enhancements in material properties and production efficiency by eliminating unnecessary process steps. Dynamic compaction [...] Read more.

Powder metallurgy (PM) offers several advantages over conventional melt metallurgy, including improved homogeneity, fine grain size, and pseudo-alloying capabilities. Transitioning from conventional methods to PM can result in significant enhancements in material properties and production efficiency by eliminating unnecessary process steps. Dynamic compaction techniques, such as impulse and explosive compaction, aim to achieve higher powder density without requiring sintering, further improving PM efficiency. Among these techniques, magnetic pulse compaction (MPC) has gained notable interest due to its unique process mechanics and distinct advantages. MPC utilizes the rapid discharge of energy stored in capacitors to generate a pulsed electromagnetic field, which accelerates a tool to compress the powder. This high-speed process is particularly well-suited for compacting complex geometries and finds extensive application in industries such as powder metallurgy, welding, die forging, and advanced material manufacturing. This paper provides an overview of recent advancements and applications of MPC technology, highlighting its capabilities and potential for broader integration into modern manufacturing processes. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

29 pages, 31952 KiB

Open AccessArticle

Aluminum and Inorganic Natural Pigment Colored Composites by Powder Metallurgy Forming

by Miguel Angel Martínez and Juana Abenojar

Metals 2025, 15(1), 58; https://doi.org/10.3390/met15010058 - 11 Jan 2025

Viewed by 666

Abstract

Aluminum powder, along with other powders such as steel or stainless steel, is extensively used in powder metallurgy (PM) to produce complex samples with irregular geometric shapes. PM enables the incorporation of fillers to modify the physical, mechanical, or wear properties of aluminum [...] Read more.

Aluminum powder, along with other powders such as steel or stainless steel, is extensively used in powder metallurgy (PM) to produce complex samples with irregular geometric shapes. PM enables the incorporation of fillers to modify the physical, mechanical, or wear properties of aluminum without melting, thereby preventing phase segregation. The novelty of this work lies in the use of inorganic natural pigments (INPs). The primary goal of this study is to produce colored aluminum samples via PM without compromising their mechanical properties. INPs are first characterized to select those with the highest heat resistance. The composites are fabricated with different pigments (10 wt%), formed through uniaxial compaction at 500 MPa, and sintered in a nitrogen atmosphere at 610 °C for 30 min. Density, color, bending strength, and wear are evaluated to identify the most suitable pigment for gas kitchen burners. Mars red, Cobalt blue, and Chrome green pigments provide the best coloration. Dimensional variation is generally less than 1%. The pigments increase the material’s brittleness by 41% to 77%, resulting in a bending modulus increase of up to 160% and deformation reduction of up to 70%. In some cases, intermetallic compounds improve bending strength, as in Al–Chrome green, by 30%. Al–Chrome green exhibits wear resistance comparable to aluminum, with a 40% lower friction coefficient. X-ray diffraction and SEM-EDX confirm AlCr and AlCo intermetallic particles. Thermal stability is verified after 160 heating and cooling cycles without significant material degradation. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

22 pages, 11171 KiB

Open AccessArticle

Influence of the Injection Process on Two-Phase Separation in Stainless-Steel Metal Powder Injection Molding

by Yan Li, Xingjie Peng, Xiang Zan, Laima Luo and Yucheng Wu

Metals 2025, 15(1), 38; https://doi.org/10.3390/met15010038 - 3 Jan 2025

Viewed by 727

Abstract

A common issue encountered in metal powder injection molding is the separation of the powder and binder during the injection process, which can give rise to a number of defects. In order to investigate the phenomenon of phase separation in stainless-steel injected flat [...] Read more.

A common issue encountered in metal powder injection molding is the separation of the powder and binder during the injection process, which can give rise to a number of defects. In order to investigate the phenomenon of phase separation in stainless-steel injected flat parts, a numerical simulation methodology was employed by using the Moldex3D R14.0 finite element software to simulate the injection process. Then, the impact of injection parameters on separation was analyzed by comparing key performance indicators such as powder volumetric concentration and density. Furthermore, the extent of the separation was minimized by the optimization of process parameters. The simulation results indicate that the separation of binder and powder is most severe near the gate, where the binder percentage is the highest. The application of elevated mold temperatures, augmented injection rates and reduced injection temperatures can effectively mitigate the two-phase separation phenomenon and enhance the uniformity of powder distribution. This provides a crucial theoretical foundation and technical support for the enhancement of the quality and performance of metal powder injection products. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

14 pages, 4618 KiB

Open AccessArticle

Microstructural and Morphological Properties of AlNiCo and CoNi Alloys: An In-Depth Study Based on Low-Energy Mechanical Alloying

by Gilberto Cruz Nieto, Jesús Noé Rivera Olvera, Sebastián Díaz de la Torre, Vicente Garibay Febles, Jesús Palacios Gómez, Leonardo Gonzalez Reyes and Lucía Graciela Diaz Barriga Arceo

Metals 2024, 14(11), 1307; https://doi.org/10.3390/met14111307 - 20 Nov 2024

Viewed by 944

Abstract

This study focused on synthesizing AlNiCo and CoNi materials using a low-energy milling process. The aim was to explore the formation of low-energy phases in both systems, contrasting with the typical research on phases formed under high-energy conditions. In the Co-20 wt% Ni [...] Read more.

This study focused on synthesizing AlNiCo and CoNi materials using a low-energy milling process. The aim was to explore the formation of low-energy phases in both systems, contrasting with the typical research on phases formed under high-energy conditions. In the Co-20 wt% Ni system, the phases

{Co}_{0.75} {Ni}_{0.25}

and Ni were identified, as well as the FCC cubic phase of CoNi, using X-ray diffraction (XRD) with a molybdenum radiation source. The observed behavior aligned closely with the miscibility curve in the equilibrium phase diagram, which included a region of alloys with varying structures and similar compositions. A notable feature was the presence of a predominantly dispersed hexagonal Ni zone, consisting of nanoparticles. Transmission electron microscopy (TEM) was employed to observe the FCC CoNi phase, which displayed a specific arrangement. AlNiCo and CoNi alloys were successfully synthesized through mechanical alloying, incorporating equilibrium and non-equilibrium phases. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

10 pages, 12271 KiB

Open AccessArticle

Effect of Ball Milling Parameters on Properties of Nano-Sized Tungsten Powder via Mechanochemical Processing

by Feng Li, Guihang Zhang, Pengfei Zheng, Wei Qian, Yaxia Wei, Bingsheng Li, Ming Zhang, Zhijie Zhang and Tong Che

Metals 2024, 14(9), 1079; https://doi.org/10.3390/met14091079 - 20 Sep 2024

Viewed by 1189

Abstract

Nano-sized tungsten exhibits superior properties due to its high-density grain boundaries’ strengthening. The high-quality nano-sized powder is essential for sintering nano-sized tungsten bulks through powder metallurgy techniques. In this study, nano-sized tungsten powder was successfully synthesized by mechanochemical methods using mixed WO₃ [...] Read more.

Nano-sized tungsten exhibits superior properties due to its high-density grain boundaries’ strengthening. The high-quality nano-sized powder is essential for sintering nano-sized tungsten bulks through powder metallurgy techniques. In this study, nano-sized tungsten powder was successfully synthesized by mechanochemical methods using mixed WO₃ and Mg powders. The effects of processing parameters on the morphology and microstructure of synthesized powder were thoroughly investigated. The results reveal that the thermite reaction of WO₃ and Mg is almost complete after 5 min of ball milling at a speed of 300 rpm. The average grain size of the tungsten powder decreases with the increasing milling duration and speed. Optimal average grain size and purity were achieved at a milling speed of 300 rpm and a milling duration ranging from 30 to 120 min. Moreover, centrifugation sieving further reduces the average grain size of tungsten powder to 19.5 nm. In addition, the entire mechanochemical process can be divided into two stages: the reaction stage and the grain size refinement stage. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

18 pages, 14710 KiB

Open AccessArticle

Full Density Powder Metallurgical Cold Work Tool Steel through Nitrogen Sintering and Capsule-Free Hot Isostatic Pressing

by Anok Babu Nagaram, Giulio Maistro, Erik Adolfsson, Yu Cao, Eduard Hryha and Lars Nyborg

Metals 2024, 14(8), 914; https://doi.org/10.3390/met14080914 - 12 Aug 2024

Cited by 1 | Viewed by 1254

Abstract

Vanadis 4E (V4E) is a powder metallurgical cold work tool steel predominantly used in application with demand for wear resistance, high hardness, and toughness. It is of interest to have a processing route that enables full density starting from clean gas-atomized powder allowing [...] Read more.

Vanadis 4E (V4E) is a powder metallurgical cold work tool steel predominantly used in application with demand for wear resistance, high hardness, and toughness. It is of interest to have a processing route that enables full density starting from clean gas-atomized powder allowing component shaping capabilities. This study presents a process involving freeze granulation of powder to facilitate compaction by means of cold isostatic pressing, followed by sintering to allow for capsule-free hot isostatic pressing (HIP) and subsequent heat treatments of fully densified specimens. The sintering stage has been studied in particular, and it is shown how sintering in pure nitrogen at 1150 °C results in predominantly closed porosity, while sintering at 1200 °C gives near full density. Microstructural investigation shows that vanadium-rich carbonitride (MX) is formed as a result of the nitrogen uptake during sintering, with coarser appearance for the higher temperature. Nearly complete densification, approximately 7.80 ± 0.01 g/cm³, was achieved after sintering at 1200 °C, and after sintering at 1150 °C, followed by capsule-free HIP, hardening, and tempering. Irrespective of processing once the MX is formed, the nitrogen is locked into this phase and the austenite is stabilised, which means any tempering tends to result in a mixture of austenite and tempered martensite, the former being predominate during the sequential tempering, whereas martensite formation during cooling from austenitization temperatures becomes limited. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Figure 1

Review

Jump to: Research

45 pages, 40831 KiB

Open AccessReview

Microstructure and Fatigue Behavior of PM-HIPed Ni-Based Superalloys and Martensitic Tool Steels: A Review

by Faezeh Javadzadeh Kalahroudi, Fengxiang Lin, Pavel Krakhmalev and Mikael Grehk

Metals 2024, 14(10), 1159; https://doi.org/10.3390/met14101159 - 11 Oct 2024

Cited by 2 | Viewed by 2584

Abstract

Hot isostatic pressing (HIP) is a near-net shape powder metallurgy (PM) technique, which has emerged as an efficient technique, offering precise control over the microstructure and properties of materials, particularly in high-performance alloys. This technology finds applications across a wide range of industries, [...] Read more.

Hot isostatic pressing (HIP) is a near-net shape powder metallurgy (PM) technique, which has emerged as an efficient technique, offering precise control over the microstructure and properties of materials, particularly in high-performance alloys. This technology finds applications across a wide range of industries, such as aerospace, automotive, marine, oil and gas, medical, and tooling. This paper provides an overview of powder metallurgy and hot isostatic pressing, covering their principles, process parameters, and applications. Additionally, it conducts an analysis of PM-HIPed alloys, focusing on their microstructure and fatigue behavior to illustrate their potential in diverse engineering applications. Specifically, this paper focuses on nickel-based superalloys and martensitic tool steels. The diverse microstructural characteristics of these alloys provide valuable insights into the PM-HIP-induced fatigue defects and properties. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Powder Metallurgy of Metallic Materials

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI