Effect of magnetic field on interfacial energy and precipitation behavior of carbides in reduced activation steels

Understanding the nature of the magnetic-field-induced precipitation behaviors represents a major step forward towards unravelling the real nature of interesting phenomena in Fe-based alloys and especially towards solving the key materials problem for the development of fusion energy. Experimental results indicate that the applied high magnetic field effectively promotes the precipitation of M23C6 carbides. We build an integrated method, which breaks through the limitations of zero temperature and zero external field, to concentrate on the dependence of the stability induced by the magnetic effect, excluding the thermal effect. We investigate the intimate relationship between the external field and the origins of various magnetics structural characteristics, which are derived from the interactions among the various Wyckoff sites of iron atoms, antiparallel spin of chromium and Fe-C bond distances. The high-magnetic-field-induced exchange coupling increases with the strength of the external field, which then causes an increase in the parallel magnetic moment. The stability of the alloy carbide M23C6 is more dependent on external field effects than thermal effects, whereas that of M2C, M3C and M7C3 is mainly determined by thermal effects.

Section: Introductionmentioning

confidence: 99%

Magnetism and high magnetic-field-induced stability of alloy carbides in Fe-based materials

Hou

Liu

et al. 2018

“…The BCC and B2 structure is coherently present in CoFeCrNi–Al x 15 , 16 and results in a change in strain and interfacial energy 17 , 18 . This may change the magnetisation of the composition as magnetic fields have been shown to affect interfacial energy in steel 19 , which have similar alloying elements to CoFeCrNi–Al x . Taken together, this suggests that to maximise saturation magnetisation in this composition, heat treatment to promote nucleation and growth of the disordered structure is required.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of the complex concentrated alloy system CoFeNi0.5Cr0.5Alx

Morley

Quintana-Nedelcos

et al. 2020

We study the change in magnetisation with paramagnetic Al addition in the CoFeNi 0.5 cr 0.5-Al x (x: 0, 0.5, 1, and 1.5) complex concentrated alloy. The compositions were developed utilising the Mulliken electronegativity and d-electron/atom ratio. Spherical FeCr rich nanoprecipitates are observed for X: 1.0 and 1.5 in an AlCoNi-rich matrix. A ~ 5 × increase in magnetisation (from 22 to 96 Am 2 /kg) coincides with this nanoprecipitate formation-the main magnetic contribution is determined to be from FeCr nanoprecipitates. The magnetisation increase is strange as paramagnetic Al addition dilutes the ferromagnetic Fe/Co/Ni additions. In this paper we discuss the magnetic and structural characterisation of the cofeni 0.5 cr 0.5-Al x composition and attempt to relate it to the interfacial energy. The innovation of new materials has been deemed to be the key topic for development of new technologies in our modern world. For alloys, the traditional approach has been to consider the effect of multiple dilute additions to a larger alloy matrix. New complex concentrated alloys (CCAs), which are near-equimolar multiple element alloys (> 3) challenge this view and have pushed alloy research towards the centre of phase diagrams 1,2. Multiple alloying components mean that they can possess large property permutations owing to the vast compositional space that they cover. Considerable work has been done on understanding how compositionalstructure affects mechanical properties. However, their functional properties are rarely the primary focus. As the base elements of CCAs are often CoFeNi (which is a known soft magnetic alloy), this can provide a basis for alloy design 1-5. Our motivation in this work is to therefore investigate the potential of CCAs as soft magnetic materials.

“…For example, it is well-known that electrical resistivity can be tuned by interfaces which usually act as obstacles to charge carriers10. More over, it has been suggested that the density and atomic structure of dissimilar interfaces underpin the mechanical and physical properties of the materials by exerting influence on nucleation and slip of dislocations, the kinetics of charge carriers and so on111213141516. Extensive studies on metallic multilayers have demonstrated that the strength of multilayers increases with decreasing monolayer thicknesses while the total thicknesses of the films remain constant1718.…”

mentioning

confidence: 99%

What determines the interfacial configuration of Nb/Al2O3 and Nb/MgO interface

Fang

et al. 2016

Nb films are deposited on single crystal Al2O3 (110) and MgO(111) substrates by e-beam evaporation technique. Structure of Nb films and orientation relationships (ORs) of Nb/Al2O3 and Nb/MgO interface are studied and compared by the combination of experiments and simulations. The experiments show that the Nb films obtain strong (110) texture, and the Nb film on Al2O3(110) substrate shows a higher crystalline quality than that on MgO(111) substrate. First principle calculations show that both the lattice mismatch and the strength of interface bonding play major roles in determining the crystalline perfection of Nb films and ORs between Nb films and single crystal ceramic substrates. The fundamental mechanisms for forming the interfacial configuration in terms of the lattice mismatch and the strength of interface bonding are discussed.