ORCID Profile
0000-0002-5761-4981
Current Organisation
Max-Planck-Institut für Eisenforschung
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Publisher: Springer Science and Business Media LLC
Date: 28-04-2022
DOI: 10.1038/S41467-022-30019-X
Abstract: The enormous magnitude of 2 billion tons of alloys produced per year demands a change in design philosophy to make materials environmentally, economically, and socially more sustainable. This disqualifies the use of critical elements that are rare or have questionable origin. Amongst the major alloy strengthening mechanisms, a high-dispersion of second-phase precipitates with sizes in the nanometre range is particularly effective for achieving ultra-high strength. Here, we propose an alternative segregation-based strategy for sustainable steels, free of critical elements, which are rendered ultrastrong by second-phase nano-precipitation. We increase the Mn-content in a supersaturated, metastable Fe-Mn solid solution to trigger compositional fluctuations and nano-segregation in the bulk. These fluctuations act as precursors for the nucleation of an unexpected α-Mn phase, which impedes dislocation motion, thus enabling precipitation strengthening. Our steel outperforms most common commercial alloys, yet it is free of critical elements, making it a new platform for sustainable alloy design.
Publisher: Elsevier BV
Date: 2020
DOI: 10.2139/SSRN.3759133
Publisher: Springer Science and Business Media LLC
Date: 05-09-2020
DOI: 10.1007/S11661-020-05947-2
Abstract: This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, formable steels that are designed mainly as sheet products for the transportation sector. AHSS have often very complex and hierarchical microstructures consisting of ferrite, austenite, bainite, or martensite matrix or of duplex or even multiphase mixtures of these constituents, sometimes enriched with precipitates. This complexity makes it challenging to establish reliable and mechanism-based microstructure–property relationships. A number of excellent studies already exist about the different types of AHSS (such as dual-phase steels, complex phase steels, transformation-induced plasticity steels, twinning-induced plasticity steels, bainitic steels, quenching and partitioning steels, press hardening steels, etc .) and several overviews appeared in which their engineering features related to mechanical properties and forming were discussed. This article reviews recent progress in the understanding of microstructures and alloy design in this field, placing particular attention on the deformation and strain hardening mechanisms of Mn-containing steels that utilize complex dislocation substructures, nanoscale precipitation patterns, deformation-driven transformation, and twinning effects. Recent developments on microalloyed nanoprecipitation hardened and press hardening steels are also reviewed. Besides providing a critical discussion of their microstructures and properties, vital features such as their resistance to hydrogen embrittlement and damage formation are also evaluated. We also present latest progress in advanced characterization and modeling techniques applied to AHSS. Finally, emerging topics such as machine learning, through-process simulation, and additive manufacturing of AHSS are discussed. The aim of this viewpoint is to identify similarities in the deformation and damage mechanisms among these various types of advanced steels and to use these observations for their further development and maturation.
Publisher: Springer Science and Business Media LLC
Date: 10-08-2022
DOI: 10.1038/S41586-022-04935-3
Abstract: Soft magnetic materials (SMMs) serve in electrical applications and sustainable energy supply, allowing magnetic flux variation in response to changes in applied magnetic field, at low energy loss 1 . The electrification of transport, households and manufacturing leads to an increase in energy consumption owing to hysteresis losses 2 . Therefore, minimizing coercivity, which scales these losses, is crucial 3 . Yet meeting this target alone is not enough: SMMs in electrical engines must withstand severe mechanical loads that is, the alloys need high strength and ductility 4 . This is a fundamental design challenge, as most methods that enhance strength introduce stress fields that can pin magnetic domains, thus increasing coercivity and hysteresis losses 5 . Here we introduce an approach to overcome this dilemma. We have designed a Fe–Co–Ni–Ta–Al multicomponent alloy (MCA) with ferromagnetic matrix and paramagnetic coherent nanoparticles (about 91 nm in size and around 55% volume fraction). They impede dislocation motion, enhancing strength and ductility. Their small size, low coherency stress and small magnetostatic energy create an interaction volume below the magnetic domain wall width, leading to minimal domain wall pinning, thus maintaining the soft magnetic properties. The alloy has a tensile strength of 1,336 MPa at 54% tensile elongation, extremely low coercivity of 78 A m −1 (less than 1 Oe), moderate saturation magnetization of 100 A m 2 kg −1 and high electrical resistivity of 103 μΩ cm.
Publisher: Elsevier BV
Date: 03-2019
Publisher: Elsevier BV
Date: 07-2021
Publisher: Research Square Platform LLC
Date: 10-12-2021
DOI: 10.21203/RS.3.RS-1145535/V1
Abstract: Soft magnetic materials (SMMs) are indispensable components in electrified applications and sustainable energy supply, allowing permanent magnetic flux variations in response to high frequency changes of the applied magnetic field, at lowest possible energy loss1. The global trend towards electrification of transport, households and manufacturing leads to a massive increase in energy consumption due to hysteresis losses2. Therefore, minimizing coercivity, which scales the losses in SMMs, is crucial3. Yet, meeting this target alone is not enough: SMMs used for instance in vehicles and planes must withstand severe mechanical loads, i.e., the alloys need high strength and ductility4. This is a fundamental design challenge, as most methods that enhance strength introduce stress fields that can pin magnetic domains, thus increasing coercivity and hysteretic losses5. Here, we introduce a new approach to overcome this dilemma. We have designed a Fe-Co-Ni-Ta-Al multicomponent alloy with ferromagnetic matrix and paramagnetic coherent nanoparticles of well-controlled size (~91 nm) and high volume fraction (55%). They impede dislocation motion, enhancing strength and ductility. Yet, their small size, low coherency stress and small magnetostatic energy create an interaction volume below the magnetic domain wall width, leading to minimal domain wall pinning, thus maintaining the material’s soft magnetic properties. The new material exhibits an excellent combination of mechanical and magnetic properties outperforming other multicomponent alloys and conventional SMMs. It has a tensile strength of ~1336 MPa at 54% tensile elongation, an extremely low coercivity of ~78 A/m ( Oe) and a saturation magnetization of ~100 Am2/kg. The work opens new perspectives on developing magnetically soft and mechanically strong and ductile materials for the sustainable electrification of industry and society.
Location: Brazil
No related grants have been discovered for Isnaldi Rodrigues de Souza Filho.