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Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: closed (10 May 2024) | Viewed by 18322

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Prof. Dr. Jairo Alberto Muñoz

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Department of Materials Science and Engineering EEBE, Universidad Politécnica de Catalunya, c/Eduard Maristany 10-14, 08019 Barcelona, Spain
Interests: superplasticity; grain refinement; additive manufacturing; nanocrystallization; microstructural heterogeneity

Prof. Dr. Jose Maria Cabrera

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Department of Materials Science and Engineering EEBE, Universidad Politécnica de Catalunya, c/Eduard Maristany 10-14, 08019 Barcelona, Spain
Interests: plastic deformation behavior of metals; mainly at high temperature; ultrafine structures and nano-grained metallic materials; severe plastic deformation processes; equal-channel angular pressing and mechanical alloying
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Prof. Dr. Raúl Eduardo Bolmaro

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Rosario Institute of Physics, Blvd. 27 de Febrero 210 Bis, Rosario- Santa Fe 2000, Argentina
Interests: metallurgy; recrystallization; crystallography; textures; synchrotron radiation and neutron diffraction characterization; electron backscatter diffraction; X-ray diffraction
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Dr. Liliana Romero Reséndiz

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Metallurgical Engineering Department, College of Chemistry, Universidad Nacional Autónoma de México, Mexico 04510, Mexico
Interests: heterostructured materials; strengthening mechanisms; biomaterials; nanomaterials; metallurgy
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Special Issue Information

Dear Colleagues,

Throughout human history, several materials, such as polymers, ceramics, and metals, have been developed to fulfill society's demands. Currently, new structural applications require functional materials with hybrid properties, such as strength and ductility. In this sense, metallic materials are a versatile option due to their wide range of mechanical and physical properties. However, homogeneous metallic materials with coarse or ultrafine/nanometric grain sizes can present large ductility or high strength, but not both simultaneously. Thus, the metallic materials’ strength–ductility paradox has been in the spotlight of the research community for at least thirty years, especially with the discovery of nanostructured materials. However, during the last ten years, huge signs of progress have been made to reach the end of this paradox. The so-called “Heterogeneous Metallic Materials” are mainly responsible for these findings; they are made up of grain families with more than a two-order-of-magnitude size difference, giving rise to zones of high strength and large ductility inside the microstructure. In these heterogeneous microstructures, the interphases between the zones of coarse and nanometric grains play a crucial role in generating new strengthening mechanisms that today represent new research opportunities.

Therefore, the proper manufacturing of heterogenous metallic materials requires the knowledge of new processing techniques and routes together with the optimum parameters that lead to a positive strength–ductility synergy. These routes can be associated with, but not limited to, severe plastic deformation plus heat treatments or the new disruptive technologies from additive manufacturing. Furthermore, understanding the behavior of heterogeneous metallic materials is essential to analyze the microstructural and mechanical variations across the interphases of the hard and soft zones where a heterogeneous deformation state occurs. Therefore, this issue invites the material science community to submit research papers dealing with the fundamentals, design, simulation, and characterization of heterogeneous metallic materials using innovative processing routes that help to understand the strengthening mechanism of these particular materials.

Prof. Jairo Alberto Muñoz
Prof. Dr. Jose Maria Cabrera
Prof. Dr. Raúl Eduardo Bolmaro
Dr. Liliana Romero Reséndiz
Guest Editors

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Keywords

heterogeneous metallic materials
hetero-deformation
Geometrically Necessary Dislocations (GNDs)
plastic gradients
strengthening mechanisms
strength–ductility ratio, additive manufacturing
plastic deformation
plasticity
severe plastic deformation.

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Published Papers (11 papers)

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Research

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14 pages, 9041 KiB

Open AccessArticle

Effect of Heat Treatment on the Microstructural Heterogeneity and Abrasive Wear Behavior of ASTM A128 Grade C Steel

by Oscar-Fabián Higuera-Cobos, María-Mercedes Cely-Bautista and Jairo-Alberto Muñoz-Bolaños

Materials 2024, 17(12), 2884; https://doi.org/10.3390/ma17122884 - 13 Jun 2024

Viewed by 821

Abstract

Microstructural heterogeneities of an ASTM A128 grade C steel subjected to heat treatments and their effect on abrasive wear behavior were investigated. The heat-treatment process involved different austenization times at 1050 °C and quenching media. To characterize the effects of heat treatment on the material’s microstructure and mechanical behavior, two microscopy techniques were used: optical microscopy (OM), and scanning electron microscopy (SEM). The chemical composition of the material was obtained using X-ray fluorescence (XRF) optical emission spectrometry. The variation in carbide composition was evaluated using X-ray Energy Dispersive Spectroscopy (EDS). To characterize the mechanical behavior of the steel, hardness measurements and abrasive wear tests were performed after homogenization annealing and quenching treatments. The results showed that the heat-treated samples developed a heterogeneous microstructure, with the presence of austenitic grains and Martensite around the surface of the samples induced by decarburization in both the protected and unprotected specimens. The specimens with lower decarburization presented less formation of Martensite and precipitated carbides, resulting in lower hardness values and higher abrasion resistance (solution treatment at 1080 °C for 1 h + sand protection + brine quenching). Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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18 pages, 97482 KiB

Open AccessArticle

Fracture Behavior and Mechanism of Nb-Si-Based Alloys with Heterogeneous Layered Structure

by Sheng Wang, Xiaoli Wang, Zhiming Wang, Zhiping Sun, Weicheng Ye and Qihu Zhao

Materials 2024, 17(11), 2735; https://doi.org/10.3390/ma17112735 - 4 Jun 2024

Viewed by 927

Abstract

Novel Nb-Si-based alloys with heterogeneous layers that have the same composition (Nb-16 at.%Si) but different phase morphologies were designed in this work. Heterogeneous layered structure (HLS) was successfully fabricated in Nb-16Si alloys by layering composite powders after various degrees of mechanical alloying (6 h, 12 h, 18 h, and 24 h) alternately and subsequent spark plasma sintering (SPS). The influence of HLS on the fracture behavior at both room and elevated temperature was investigated via single-edge notched bending (SENB) and high-temperature compression, respectively. The results show that the diversified HLS is obtained by combining hard layers containing fine equiaxed crystals and/or soft ones with coarse lamellar niobium solid solution (Nbss). By affecting the crack propagation in SENB, HLS is favorable for improving the fracture toughness and exhibits a significant increase compared with the corresponding homogenous microstructure. Moreover, for the same HLS, a more excellent performance is achieved when the initial crack is located in the soft layer and extended across the interface to the hard one through crack bridging, crack deflection, crack branching, and shielding effect. Fracture starts in the soft layer (from powders of ball-milled for 12 h) of a 12–24 alloy, and a maximum K_Q value (14.89 MPa·mm^1/2) is consequently obtained, which is 33.8% higher than that of the homogeneous Nb-16Si alloy. Furthermore, the heterogeneous layered alloys display superior high-temperature compression strength, which is attributable to the dislocation multiplication and fine-grained structure. The proposed strategy in this study offers a promising route for fabricating Nb-Si-based alloys with optimized and improved mechanical properties to meet practical applications. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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16 pages, 12196 KiB

Open AccessArticle

Deformation Behavior and Microstructure of 6061 Aluminum Alloy Processed by Severe Plastic Deformation Using Biaxial Alternate Forging

by Seong-Ho Ha and Young-Chul Shin

Materials 2024, 17(5), 968; https://doi.org/10.3390/ma17050968 - 20 Feb 2024

Cited by 1 | Viewed by 1285

Abstract

The deformation behavior and microstructure of 6061 aluminum alloy processed by severe plastic deformation (SPD) using biaxial alternate forging that can evaluate the forming limit and mechanical properties of alloys, simultaneously, were investigated in this study. A finite element (FE) analysis on the biaxial alternating forging process, considering the strain-hardening coefficient and forging pass of the material, was conducted. When the strain-hardening coefficient is 0, an average effective strain of 440% was found within a diameter of 4 mm in the core of the workpiece after eight passes, while it was 300% at the same pass number when the strain-hardening coefficient was 0.2. The average effective strain estimated from the FE analysis was about 264% after eight passes of forging, which is considered to be a level of SPD that significantly exceeds the elongation of the raw material. As a result of the tensile test according to the forging pass, after two passes, the strength of the material could be gradually improved without significant degradation of elongation. Even though a large strain of 264% was found after eight passes were applied, deformed grains and twins with no recrystallized structure in optical microstructures with different forging passes were found. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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11 pages, 4030 KiB

Open AccessArticle

Enhanced Microstructure and Wear Resistance of Ti–6Al–4V Alloy with Vanadium Carbide Coating via Directed Energy Deposition

by Ui Jun Ko, Ju Hyeong Jung, Jung Hyun Kang, Kyunsuk Choi and Jeoung Han Kim

Materials 2024, 17(3), 733; https://doi.org/10.3390/ma17030733 - 3 Feb 2024

Cited by 2 | Viewed by 1279

Abstract

Ti–6Al–4V alloys are known for their suboptimal tribological properties and are often challenged by durability issues under severe wear conditions. This study was conducted to enhance the alloy’s wear resistance by forming a hardened surface layer. Utilizing directed energy deposition (DED) additive manufacturing with a diode laser, vanadium carbide particles were successfully integrated onto a Ti–6Al–4V substrate. This approach deviates from traditional surface enhancement techniques like surface hardening and cladding, as it employs DED additive manufacturing under parameters akin to those used in standard Ti–6Al–4V production. The formed vanadium carbide layer achieved a remarkable thickness of over 400 µm and a Vickers hardness surpassing 1500 HV. Pin-on-disk test results further corroborated the enhanced surface wear properties of the Ti–6Al–4V alloy following the additive-manufacturing process. These findings suggest that employing vanadium carbide additive manufacturing, under conditions similar to the conventional DED process with a diode laser, significantly improves the surface wear properties of Ti–6Al–4V in metal 3D-printing applications. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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17 pages, 7115 KiB

Open AccessArticle

Change in Mechanical Properties of Laser Powder Bed Fused AlSi7Mg Alloy during Long-Term Exposure at Warm Operating Temperatures

by Emanuela Cerri and Emanuele Ghio

Materials 2023, 16(24), 7639; https://doi.org/10.3390/ma16247639 - 14 Dec 2023

Cited by 1 | Viewed by 1209

Abstract

Al–Si–Mg alloys are most commonly used to produce parts by laser powder bed fusion for several industrial applications. A lot of papers have already focused on the effects induced by conventional heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys, rather than on AlSi7Mg. Nobody has investigated thermal stability during long-term direct and artificial aging heat treatments of AlSi7Mg. This study investigates the changes in mechanical properties induced by long-term exposure (512 h) at 150 and 175 °C (the operating temperature of AlSi7Mg) after (i) the laser powder bed fusion process performed on a pre-heated build platform (150 °C), and (ii) heat treatments to the solution at 505 °C per 0.5 and 4 h. Thermal stability was evaluated through both Vickers microhardness measurements to obtain the aging profiles, and tensile tests to evaluate the mechanical properties in specific conditions. An optical microscope was used to investigate the microstructure. It was found that aging at 175 °C confers the same effects induced by a secondary aging heat treatment on as-built samples and, simultaneously, the worst effects on the solution heat treated AlSi7Mg alloy after long-term exposure. The AlSi7Mg DA at both 150 °C and 175 °C showed the same Vickers microhardness (~95 HV0.5), UTS (~300 MPa), and YS (~200 MPa) values for the longest exposure times because the fine and cellular α-Al matrix confers higher stiffness and strength despite the over-aged conditions. On the other hand, the coarsening effects that affected the precipitates during aging at 175 °C, as well as the formation of the precipitate-free zones along the grain boundaries, justified the highest detrimental effects induced on the SHTed samples. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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12 pages, 5984 KiB

Open AccessArticle

Optimization of Aging Temperature and Heat-Treatment Pathways in Additively Manufactured 17-4PH Stainless Steel

by Hobyung Chae, Sangyeob Lim, Taeho Lee, Eunjoo Shin, Joowon Suh, Suk Hoon Kang and Soo Yeol Lee

Materials 2023, 16(24), 7557; https://doi.org/10.3390/ma16247557 - 8 Dec 2023

Viewed by 1472

Abstract

This study investigates the tensile behaviors of additively manufactured (AM) 17-4PH stainless steels heat-treated within various temperature ranges from 400 °C to 700 °C in order to identify the effective aging temperature. Despite an aging treatment of 400–460 °C increasing the retained austenite content, an enhancement of the tensile properties was achieved without a strength-ductility trade-off owing to precipitation hardening by the Cu particles. Due to the intricate evolution of the microstructure, aging treatments above 490 °C led to a loss in yield strength and ductility. A considerable rise in strength and a decrease in ductility were brought about by the increase in the fraction of precipitation-hardened martensitic matrix in aging treatments over 640 °C. The impact of heat-treatment pathways on aging effectiveness and tensile anisotropy was then examined. Direct aging at 482 °C for an hour had hardly any effect on wrought 17-4PH, but it increased the yield strength of AM counterparts from 436–457 to 588–604 MPa. A solid-solution treatment at 1038 °C for one hour resulted in a significant drop in the austenite fraction, which led to an increase in the yield (from 436–457 to 841–919 MPa) and tensile strengths (from 1106–1127 to 1254–1256 MPa) with a sacrifice in ductility. Improved strength and ductility were realized by a solid-solution followed by an aging treatment, achieving 1371–1399 MPa. The tensile behaviors of AM 17-4PH were isotropic both parallel and perpendicular to the building direction. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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21 pages, 18351 KiB

Open AccessArticle

Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

by Marzena M. Lachowicz, Maciej Zwierzchowski, Marek Hawryluk, Zbigniew Gronostajski and Marta Janik

Materials 2023, 16(19), 6370; https://doi.org/10.3390/ma16196370 - 23 Sep 2023

Viewed by 1115

Abstract

This paper focused on determining the increased tendency of cracking after the die forging process of high nickel and chromium steel. The increase in carbon content in austenitic nickel–chromium steel promoted the tendency of valve forgings to forging intergranular crack on the valve head. Attention was paid to issues related to the chemical composition of the material to be considered when hot forming nickel–chromium steel components. Optical and scanning electron microscopies were used to examine the microstructure and fracture features of the samples removed from a fractured valve head. The embrittlement was due to microcavity formation at grain boundaries. Creep theory at grain boundaries was used to explain crack formation. The tensile behavior was interpreted from the evolution of the microstructure during deformation and referred to intermediate brittleness to explain the effect of carbon. It was found that the increased carbon content of the nickel–chromium steel and the strong undercooling observed at the edges of the valve head are factors that promote a reduction in grain boundary cohesion and enhance intermediate temperature embrittlement. Finally, it was found that the formation of a heterogeneous structure manifested by the presence of grain boundary M₂₃C₆-type carbides in the austenitic matrix was most likely related to the occurring brittleness. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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17 pages, 7072 KiB

Open AccessArticle

Influence of Preheating Temperature on the Microstructure and Mechanical Properties of 6061/TA1 Composite Plates Fabricated by AFSD

by Wei Gong, Yidi Li, Ming Zhang, Hui Wang, Qinglin Liu, Ziming Zeng, Kuo Ma, Biaobiao Yang, Ruilin Lai and Yunping Li

Materials 2023, 16(17), 6018; https://doi.org/10.3390/ma16176018 - 1 Sep 2023

Cited by 9 | Viewed by 1629

Abstract

In this study, composite plates of 6061/TA1 were successfully manufactured using additive friction stir deposition (AFSD). The impact of preheating temperatures (room temperature, 100 °C, 200 °C) on the interfacial microstructure and interface mechanical properties at various deposition zones was studied. The results showed that as the preheating temperature increased or when the deposit zone shifted from the boundary to the center, the diffusion width of Al and Ti increased, accompanied by an increase in bonding shear strength. Moreover, in the boundary zone of the sample preheated at room temperature (P-RT), only mechanical bonding was observed, resulting in the lowest bonding shear strength. Conversely, the other samples exhibited a combination of mechanical and metallurgical bonding. Under the preheating temperature of 200 °C, interfacial intermetallic compounds were observed near the center zone, which exhibited the highest bonding shear strength. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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14 pages, 5522 KiB

Open AccessArticle

Design of Ti64/Ta Hybrid Materials by Powder Metallurgy Mimicking Bone Structure

by Francisco Alvarado-Hernández, Elena Mihalcea, Omar Jimenez, Rogelio Macías, Luis Olmos, Enrique A. López-Baltazar, Santiago Guevara-Martinez and José Lemus-Ruiz

Materials 2023, 16(12), 4372; https://doi.org/10.3390/ma16124372 - 14 Jun 2023

Cited by 2 | Viewed by 1250

Abstract

This work reports on the fabrication of a novel two-layer material composed of a porous tantalum core and a dense Ti6Al4V (Ti64) shell by powder metallurgy. The porous core was obtained by mixing Ta particles and salt space-holders to create large pores, the green compact was obtained by pressing. The sintering behavior of the two-layer sample was studied by dilatometry. The interface bonding between the Ti64 and Ta layers was analyzed by SEM, and the pore characteristics were analyzed by computed microtomography. Images showed that two distinct layers were obtained with a bonding achieved by the solid-state diffusion of Ta particles into Ti64 during sintering. The formation of β-Ti and α′ martensitic phases confirmed the diffusion of Ta. The pore size distribution was in the size range of 80 to 500 µm, and a permeability value of 6 × 10⁻¹⁰ m² was close to the trabecular bones one. The mechanical properties of the component were dominated mainly by the porous layer, and Young’s modulus of 16 GPa was in the range of bones. Additionally, the density of this material (6 g/cm³) was much lower than the one of pure Ta, which helps to reduce the weight for the desired applications. These results indicate that structurally hybridized materials, also known as composites, with specific property profiles can improve the response to osseointegration for bone implant applications. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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15 pages, 6865 KiB

Open AccessArticle

The Effect of Initial Texture on the Plastic Deformation of Gradient Aluminum

by Hao Lyu, Yaxin Zhang, Yuan Bao and Jiahui Zhang

Materials 2023, 16(7), 2603; https://doi.org/10.3390/ma16072603 - 24 Mar 2023

Viewed by 1434

Abstract

The effect of specific processing-induced surface textures in gradient aluminum has not yet been investigated. A dislocation-based multi-scale framework is employed to explore the influence of various initial shearing textures and the depth from the surface of the region featuring each texture on the macroscopic behavior of gradient aluminum. By assigning different textures to the same grain size gradient aluminum sample, the initial texture was found to significantly affect the plastic deformation and macroscopic behavior of gradient aluminum. Specifically, the {111} texture can enhance the strength–ductility synergy, and this effect is dependent on the depth from the surface where the texture is located. This texture can lead to a slow stress/strain gradient in the assigned texture region and a sharp stress/strain gradient in the grain size gradient region connecting this region with the coarse grain region. Particularly, the sharp stress/strain gradient can result in extra strengthening by adjusting the stress/strain localization. These findings provide valuable insights for the design and optimization of surface textures in gradient aluminum. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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Review

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56 pages, 6314 KiB

Open AccessReview

Current Trends in Metallic Materials for Body Panels and Structural Members Used in the Automotive Industry

by Tomasz Trzepieciński and Sherwan Mohammed Najm

Materials 2024, 17(3), 590; https://doi.org/10.3390/ma17030590 - 25 Jan 2024

Cited by 17 | Viewed by 4108

Abstract

The development of lightweight and durable materials for car body panels and load-bearing elements in the automotive industry results from the constant desire to reduce fuel consumption without reducing vehicle performance. The investigations mainly concern the use of these alloys in the automotive industry, which is characterised by mass production series. Increasing the share of lightweight metals in the entire structure is part of the effort to reduce fuel consumption and carbon dioxide emissions into the atmosphere. Taking into account environmental sustainability aspects, metal sheets are easier to recycle than composite materials. At the same time, the last decade has seen an increase in work related to the plastic forming of sheets made of non-ferrous metal alloys. This article provides an up-to-date systematic overview of the basic applications of metallic materials in the automotive industry. The article focuses on the four largest groups of metallic materials: steels, aluminium alloys, titanium alloys, and magnesium alloys. The work draws attention to the limitations in the development of individual material groups and potential development trends of materials used for car body panels and other structural components. Full article

(This article belongs to the Special Issue Mechanical and Microstructural Behaviour of Heterogeneous Metallic Materials)

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