Special Issue "High Performance Nonferrous Alloys: Composition, Microstructure and Properties"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 May 2020.

Special Issue Editor

Prof. Dr. Tomasz Czujko
Website
Guest Editor
Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Gen. S. Kaliskiego 2, 00-908 Warsaw, Poland
Interests: additive manufacturing: personalized implants, titanium alloys; clean energy: the hydrogen economy; nanotechnology: nanomaterials for solid state hydrogen storage; nanostructured magnetic and superconducting materials; intermetallics and other advanced materials
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Special Issue Information

Dear Colleagues,

Performance of nonferrous alloys in terms of their mechanical properties, corrosion and abrasion resistance, fatigue resistance, and so on, is significantly affected by their composition and microstructure, including their phase composition, grain shape and size, grain boundary distribution, dislocation density, dispersed particles and solutes, internal stresses, and so on. Therefore, studies on the relationships between the composition, microstructure, and various properties are of a great practical importance. The development of new nonferrous metallic constructive and functional materials with a desired structure results in beneficial combinations of mechanical properties and performance. Various thermo-mechanical treatments are widely used to produce metallic materials, with a preferred microstructure achieved owing to the diverse mechanisms of its evolution. The knowledge about the effect of the composition and applied techniques, as well as the processing window on the structural changes in the nonferrous alloys provides the development of manufacturing methods of structural materials with an enhanced performance. The aim of this Special Issue is to present the latest achievements in the theoretical and experimental investigations of the composition and microstructural changes in various nonferrous materials subjected to different processing methods, and of their performance. In conclusion, it is my pleasure to invite all researchers from the community of nonferrous metals and alloys to submit a manuscript in the field for this Special Issue.

Prof. Tomasz Czujko
Guest Editor

Manuscript Submission Information

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Keywords

  • Nonferrous metals
  • Nonferrous alloys
  • Chemical composition
  • Microstructure and texture
  • Strengthening mechanism
  • Grain size
  • Corrosion resistance
  • Abrasion resistance
  • Mechanical properties
  • Fatigue resistance

Published Papers (6 papers)

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Research

Open AccessArticle
Microstructure and Residual Stresses of AA2519 Friction Stir Welded Joints under Different Heat Treatment Conditions
Materials 2020, 13(4), 834; https://doi.org/10.3390/ma13040834 - 12 Feb 2020
Abstract
The aim of this research was to investigate the effect of different heat treatment conditions of AA2519 friction stir welded joints on their microstructure and residual stresses. The following welding parameters have been used: 500 rpm tool rotation speed, 150 mm/min tool traverse [...] Read more.
The aim of this research was to investigate the effect of different heat treatment conditions of AA2519 friction stir welded joints on their microstructure and residual stresses. The following welding parameters have been used: 500 rpm tool rotation speed, 150 mm/min tool traverse speed, tool tilt angle 2°, pressure force 17 kN. The welded material was investigated in three different configurations: HT0, HT1, and HT2. The first type of weld (HT-0) was made using AA2519 alloy in non-precipitation hardened state and examined in such condition. The second type of weld (HT-1) has been performed on AA2519-T62, that corresponds to precipitation hardening condition. The last type of weld (HT2) was performed on annealed AA2519 and the obtained welds were subjected to the post-weld precipitation hardening process. The heat treatment was carried out in two stages: solution heat treatment (530 °C/2 h + cooling in cold water) and aging (165 °C/1 0 h). Residual stresses were measured using X-Ray diffraction patterns obtained from Bruker D8 Discover X-ray diffractometer utilizing the concepts of Euler cradle and polycapillary primary beam optics. The conducted research indicates that the best material properties: homogenous microstructure and uniform distribution of microhardness and compressive state of residual stresses were obtained for the HT-2 series samples subjected to heat treatment after the friction stir welding (FSW) process. Full article
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Open AccessArticle
A New Ultra-High-Strength AB83 Alloy by Combining Extrusion and Caliber Rolling
Materials 2020, 13(3), 709; https://doi.org/10.3390/ma13030709 - 05 Feb 2020
Abstract
An exceptionally high-strength rare-earth-free Mg–8Al–3Bi (AB83) alloy was successfully fabricated via extrusion and caliber rolling. After three-pass caliber rolling, the homogenous microstructure of the as-extruded AB83 alloy was changed to a necklace-like bimodal structure consisting of ultra-fine dynamic recrystallized (DRXed) grains and microscale [...] Read more.
An exceptionally high-strength rare-earth-free Mg–8Al–3Bi (AB83) alloy was successfully fabricated via extrusion and caliber rolling. After three-pass caliber rolling, the homogenous microstructure of the as-extruded AB83 alloy was changed to a necklace-like bimodal structure consisting of ultra-fine dynamic recrystallized (DRXed) grains and microscale deformed grains. Additionally, both Mg17Al12 and Mg3Bi2 nanoprecipitates, undissolved microscale Mg17Al12, and Mg3Bi2 particles were dispersed in the matrix of caliber-rolled (CRed) AB83 alloy. The CRed AB83 sample demonstrated a slightly weakened basal texture, compared with that of the as-extruded sample. Consequently, CRed AB83 showed a tensile yield strength of 398 MPa, an ultimate tensile strength of 429 MPa, and an elongation of 11.8%. The superior mechanical properties of the caliber-rolled alloy were mainly originated from the combined effects of the necklace-like bimodal microstructure containing ultra-fine DRXed grains, the homogeneously distributed nanoprecipitates and microscale particles, as well as the slightly modified basal texture. Full article
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Open AccessArticle
Low Cycle Fatigue Properties of Sc-Modified AA2519-T62 Extrusion
Materials 2020, 13(1), 220; https://doi.org/10.3390/ma13010220 - 04 Jan 2020
Cited by 1
Abstract
This investigation presents the results of research on low cycle fatigue properties of Sc-modified AA2519-T62 extrusion. The basic mechanical properties of the investigated alloy have been established in the tensile test. The low cycle fatigue testing has been performed on five different levels [...] Read more.
This investigation presents the results of research on low cycle fatigue properties of Sc-modified AA2519-T62 extrusion. The basic mechanical properties of the investigated alloy have been established in the tensile test. The low cycle fatigue testing has been performed on five different levels of total strain amplitude: 0.4%; 0.5%; 0.6%; 0.7% and 0.8% with cycle asymmetry coefficient R = 0.1. For each level of total strain amplitude, the graphs of variations in stress amplitude and plastic strain amplitude in the number of cycles have been presented. The obtained results allowed to establish Ramberg-Osgood and Manson-Coffin-Basquin relationships. The established values of the cyclic strength coefficient and cyclic strain hardening exponent equal to k’ = 1518.1 MPa and n’ = 0.1702. Based on the Manscon-Coffin-Basquin equation, the values of the following parameters have been established: the fatigue strength coefficient σ’f = 1489.8 MPa, the fatigue strength exponent b = −0.157, the fatigue ductility coefficient ε’f = 0.4931 and the fatigue ductility exponent c = −1.01. The fatigue surfaces of samples tested on 0.4%, 0.6% and 0.8% of total strain amplitude have been subjected to scanning electron microscopy observations. The scanning electron microscopy observations of the fatigue surfaces revealed the presence of cracks in striations in the surrounding area with a high concentration of precipitates. It has been observed that larger Al2Cu precipitates exhibit a higher tendency to fracture than smaller precipitates having a higher concentration of scandium and zirconium. Full article
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Open AccessArticle
Standard Hot Pressing as a Possible Solution to Obtain Dense K0.5Na0.5NbO3 Ceramic Doped by Er2O3 and Yb2O3
Materials 2019, 12(24), 4171; https://doi.org/10.3390/ma12244171 - 12 Dec 2019
Abstract
In this study, the influence of the addition of rare earth oxides on the phase composition and density of KNN piezoelectric ceramics was investigated. The initial powders of Na2CO3 and K2CO3 were dried at 150 °C for [...] Read more.
In this study, the influence of the addition of rare earth oxides on the phase composition and density of KNN piezoelectric ceramics was investigated. The initial powders of Na2CO3 and K2CO3 were dried at 150 °C for 2 h. Then, a powder mixture for synthesis was prepared by adding a stoichiometric amount of Nb2O5 and 5 and 10 wt % overabundance of Na2CO3. All powders were mixed by ball-milling for 24 h and synthesized at 950 °C. The phase composition of the reaction bed was checked by means of X-ray diffraction (XRD). It had an appearance of tetragonal and monoclinic K0.5Na0.5NbO3 (KNN) phases. Then, 1 and 2 wt % of Er2O3 and Yb2O3, were added to the mixture. Green samples of 25 mm diameter and 3 mm thickness were prepared and sintered by hot pressing at 1000 °C for 2 h under 25 MPa pressure. The final samples were investigated via scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS), XRD, Rietveld, and ultrasonic methods. Phase analysis showed tetragonal and orthorhombic KNN phases, and a contamination of (K2CO3·1.5H2O) was present. The obtained KNN polycrystals had a relative density above 95%. Texturing of the material was confirmed as a result of hot pressing. Full article
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Open AccessArticle
The Influence of A Cross-Channel Extrusion Process on The Microstructure and Properties of Copper
Materials 2019, 12(23), 3995; https://doi.org/10.3390/ma12233995 - 02 Dec 2019
Abstract
A new cross-channel extrusion (CCE) method with the application of a back pressure (BP) is proposed and experimentally tested. The introduction of pressure blocks the free flow of material by using an additional set of pistons, which prevents the loss of consistency. The [...] Read more.
A new cross-channel extrusion (CCE) method with the application of a back pressure (BP) is proposed and experimentally tested. The introduction of pressure blocks the free flow of material by using an additional set of pistons, which prevents the loss of consistency. The paper presents results of experimental trials of CCE process. Between one and eight passes of CCE with and without a BP were applied to pure copper billets to refine their initial coarse-grained microstructure at room temperature. It was found that processing by CCE results in the formation of a lamellar structure along the extruded axis and the fine-grained structure in the remaining volume. The material exhibited dynamic recrystallization, which results in the formation of 0.5- to 2-μm grains after one pass and 2- to 8-μm grains after four CCE passes. The fine-grained material had YS of 390-415 MPa. An increase in the microhardness from 70 to 130 HV02 after one pass and then a decrease after four passes were observed. This might indicate that secondary recrystallization and selective grain growth occur, because an exothermic peak (158.5 °C, 53 ± 2.1 J/mol) was observed during DSC (differential scanning calorimetry) testing. The resistivity of the once deformed copper significantly decreases, while its further processing causes the resistivity to increase. Full article
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Open AccessArticle
Effect of Ni/Si Mass Ratio and Thermomechanical Treatment on the Microstructure and Properties of Cu-Ni-Si Alloys
Materials 2019, 12(13), 2076; https://doi.org/10.3390/ma12132076 - 27 Jun 2019
Cited by 4
Abstract
The effect of the Ni/Si mass ratio and combined thermomechanical treatment on the microstructure and properties of ternary Cu-Ni-Si alloys is discussed systematically. The Cu-Ni-Si alloy with a Ni/Si mass ratio of 4–5 showed good comprehensive properties. Precipitates with disc-like shapes were confirmed [...] Read more.
The effect of the Ni/Si mass ratio and combined thermomechanical treatment on the microstructure and properties of ternary Cu-Ni-Si alloys is discussed systematically. The Cu-Ni-Si alloy with a Ni/Si mass ratio of 4–5 showed good comprehensive properties. Precipitates with disc-like shapes were confirmed as the Ni2Si phase with orthorhombic structure through transmission electron microscopy, high-resolution transmission electron microscopy, and 3D atom probe characterization. After the appropriate thermomechanical treatment, the studied alloy with a Ni/Si mass ratio of 4.2 exhibited excellent mechanical properties: a hardness of 290 HV, tensile strength of 855 MPa, yield strength of 782 MPa, and elongation of 4.5%. Compared with other approaches, the thermomechanical treatment increased the hardness and strength without sacrificing electrical conductivity. Theoretical calculations indicated that the high strength was primarily attributed to the Orowan precipitation strengthening and secondarily ascribed to the work hardening, which were highly consistent with the experimental results. The appropriate Ni/Si mass ratio with a low content of Ni and Si atoms shows high strength and excellent electrical conductivity through combined thermomechanical treatment. This work provides a guideline for the design and preparation of multicomponent Cu-Ni-Si-X alloys with ultrahigh strength and excellent electrical conductivity. Full article
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