The recycling of steel scrap gains increasing attention as global decarbonization efforts intensify, driving the development of sustainable alloy design that prioritizes scrap tolerance. A challenge is the presence of tramp elements such as copper (Cu) and tin (Sn), which can significantly influence material properties even at low concentrations. In this study, eight Fe–Cu and Fe–Cu–Sn alloys are investigated to elucidate the effects of chemical composition on solidification microstructure and micromechanical behavior. The results reveal a pronounced grain refinement effect induced by Cu and Sn in as-cast conditions, reducing grain size from about 130 to 13 μm. Micromechanical testing of boundaries with segregation reveals that: in Fe–Cu alloys, the boundaries are harder than the matrix due to solid solution strengthening by Cu atoms in the ferrite lattice, whereas in Fe–Cu–Sn alloys, the boundaries appeared softer, which is suggestive of the possible formation of (Cu, Sn) precipitates during solidification. These findings advance understanding of the influence of Cu and Sn on microstructure and micromechanical properties of recycled steels. Further elucidating these mechanisms and their dependence on alloying will support the development of steels with extended compositional tolerance, enhancing recyclability and promoting sustainable steel production.

Powder bed fusion laser beam (PBF-LB) is particularly effective for fabricating compositionally complex alloys such as high-entropy alloys (HEAs) or medium-entropy alloys (MEAs). Fabricating non-equiatomic metastable MEAs using PBF-LB can lead to the formation of unique microstructures that enhance the mechanical performance of these alloys. Nevertheless, plastic anisotropy in materials prepared by additive manufacturing routes including PBF-LB remains to be a technical challenge. This work presents the fabrication of a metastable non-equiatomic Co45Cr25(FeNi)30 MEA using PBF-LB. As-printed samples exhibited the formation of nano-scaled ε-martensite (HCP) phase along with the FCC phase. The HCP phase exhibited Shoji-Nishiyama orientation relationship with the FCC phase. High energy synchrotron X-ray diffraction (HEXRD) and electron backscatter diffraction (EBSD) in-situ tensile testing were employed to investigate the influence of the HCP phase on the alloy's deformation behavior. The presence of the HCP phase initiates stress-induced martensitic transformation well below the macroscopic yield strength. This transformation led to the non-linear stress and strain response for the FCC phase. Further straining resulted in significant load partitioning, with the HCP phase taking the majority of the load as it formed, significantly strain hardening the alloy and reducing the plastic anisotropy induced by texture in the as-printed material.

A crucial component of lowering the current 8% greenhouse gas emissions (GHG) from the steel industry is increasing circularity. The major obstacle toward enhanced recycling of steel is the impurities that accumulate when a larger fraction of recycled, low-quality steel needs to be used to achieve circularity. In particular, the role of tramp elements (impurities, such as Cu and Sn), which get concentrated during the recycling processes, must be better understood. In this work, we present a study on the model Fe–Cu–Sn system with binary Fe–Cu (up to 5-wt% Cu) and ternary Fe–Cu–Sn (up to 5-wt% Cu, 0.7-wt% Sn) variants. We studied the micro-segregation behavior of Cu and Sn using both experimental and computational thermodynamics and kinetics tools. We saw that up to 4–6 times segregation of Cu and Sn could be confirmed. Moreover, the high alloyed variants (greater than Fe–3Cu and Fe–1Cu–0.15Sn) showed solidification cracking which could be confirmed via microscopy and supported by Scheil solidification calculations. At the same time, alloying with Cu and Sn was seen to refine the ferrite grains in the as-cast material by more than an order of magnitude (from 108 µm → 4.9 µm average diameter). It is proposed that Cu could be successfully used in larger amounts than the current industry practice as an alloying element in steels in cases when hot shortness can be avoided. This would provide an enhanced opportunity for upcycling of lower-quality grades by providing a pathway toward increased strength due to precipitation hardening—making the process of increasing recycling of steel much more lucrative.

Powder bed fusion-laser beam (PBF-LB), an additive manufacturing process, takes advantage of rapid cooling rates (103-106 K/s) to enable novel aluminium alloys. This study reports the mechanical properties of one such alloy system (Al-Mn-Cr-Zr based). The alloys based on this system are designed to be precipitation hardenable with high service temperatures. To elucidate the precipitation hardening, three alloy variants were studied involving different heat-treated conditions. Uniaxial tensile testing at room temperature revealed yield strengths between 250–500 MPa with elongation to fracture of 5–25 % with high repeatability. To demonstrate high-temperature resistance, two alloy variants in peak hardened condition were tested at temperatures of up to 573 K. Yield strength up to 170 MPa at 573 K was observed. These properties in combination demonstrate highly competitive Al-alloys for high-temperature applications.

Featured Application The paper demonstrates key structural characteristics of a novel aluminum alloy conceived for AM-based components in the aviation frame.Abstract The recent advances achieved in additive manufacturing (AM) technology demonstrate the potential to realize customized metal components, ensuring weight reduction opportunities. These benefits make AM attractive for high-cost aerospace applications, especially where high geometric complexity is required. In the context of an EU research scenario, the H2020 MANUELA (Additive Manufacturing Using Metal Pilot Line) project promotes the development of new technologies for design optimization by enabling the application of novel materials in AM. This paper illustrates recent advances in a new aluminum alloy (Al-HS1) with high strength emphasizing all of the characterization steps at the coupon level. This material has been employed in the re-engineering of a conventional hydraulic manifold using a powder bed fusion-laser beam (PBF-LB) process. Both the simulations and structural tests allowed for proving its compliance and technological maturity with industrial standards and applicable airworthiness requirements.

Novel alloy concepts enabled via additive manufacturing processes have opened up the possibility of tailoring properties beyond the scope of conventional casting and powder metallurgy processes. The authors have previously presented a novel Al–Mn–Cr–Zr-based alloy system containing three times the equilibrium amounts of Mn and Zr. The alloys were produced via a powder bed fusion-laser beam (PBF-LB) process taking advantage of rapid cooling and solidification characteristics of the process. This supersaturation can then be leveraged to provide high precipitation hardening via direct ageing heat treatments. The hardening is enabled with Zr-rich and Mn-rich precipitates. Literature study confirms that Mn-rich precipitates have a notable solubility of Cr, for example, the Al12Mn precipitate. This study aims to clarify the effect of Cr solubility in the thermodynamics and kinetics simulation and compare the precipitation simulations with samples subject to >1000 h isothermal heat treatment, thus creating an equilibrium-like state. The results show that Cr addition to the precipitates stabilizes the Al12Mn precipitate while slowing the precipitation kinetics thus producing a favourable hardening response. Such observations could be insightful while designing such alloys and optimising heat treatments of the current or even a future alloy system.