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  • 1.
    Choi, Young Won
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Araujo, C. Moyses
    Karlstad Univ, Dept Engn & Phys, Karlstad, Sweden.;Uppsala Univ, Dept Phys & Astron, Div Mat Theory, Box 516, SE-75120 Uppsala, Sweden..
    Lizarrága, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Amorphisation-induced electrochemical stability of solid-electrolytes in Li-metal batteries: The case of Li3ClO2022Ingår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 521, artikel-id 230916Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy storage technologies that can meet the unprecedented demands of a sustainable energy system based on intermittent energy sources require new battery materials. In recent years, new superionic conducting glasses have been discovered that have captured the attention of the community due to their potential use as solid electrolytes for all-solid-state Li-ion batteries. New research is needed to understand the correlations between the non-crystalline structure of glasses and their advanced properties. Here we investigate the structural properties, the electronic structure and the electrochemical stability against Li metal of the high ionic conducting Li3ClO glass. We use the stochastic quenching method based on first principles theory to model the amorphous structure of the glass. We characterise the structure by means of radial distribution functions, angle distributions functions, bond lengths and coordination numbers. Our calculations of the electronic structure of Li3ClO for both phases, crystalline and amorphous, demonstrate that both materials are good insulators. We assess the electrochemical stability of the electrolyte against Li metal electrode and in particular we analyse the role of amorphisation. Our results show that crystalline Li3ClO is not stable against Li metal electrode and that the glass can be made stable if less oxygen is supplied, for instance, by producing an substoichiometric glass.

  • 2.
    Choi, Young Won
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Dong, Zhihua
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper. Chongqing Univ, Coll Mat Sci & Engn, State Key Lab Mech Transmission, Chongqing 400044, Peoples R China.;Chongqing Univ, Natl Engn Res Ctr Magnesium Alloys, Chongqing 400044, Peoples R China..
    Li, Wei
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper. Uppsala Univ, Div Mat Theory, Dept Phys & Astron, POB 516, SE-75121 Uppsala, Sweden..
    Lizarraga, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Kwon, Se-Kyun
    Pohang Univ Sci & Technol, Dept Phys, Pohang 37673, South Korea..
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper. Uppsala Univ, Div Mat Theory, Dept Phys & Astron, POB 516, SE-75121 Uppsala, Sweden.;Res Inst Solid State Phys & Optic, Wigner Res Ctr Phys, POB 49, H-1525 Budapest, Hungary..
    Density Functional Theory Description of Paramagnetic Hexagonal Close-Packed Iron2022Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, nr 4, artikel-id 1276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hexagonal close-packed (hcp) phase of iron is unstable under ambient conditions. The limited amount of existing experimental data for this system has been obtained by extrapolating the parameters of hcp Fe-Mn alloys to pure Fe. On the theory side, most density functional theory (DFT) studies on hcp Fe have considered non-magnetic or ferromagnetic states, both having limited relevance in view of the current understanding of the system. Here, we investigate the equilibrium properties of paramagnetic hcp Fe using DFT modelling in combination with alloy theory. We show that the theoretical equilibrium c/a and the equation of state of hcp Fe become consistent with the experimental values when the magnetic disorder is properly accounted for. Longitudinal spin fluctuation effects further improve the theoretical description. The present study provides useful data on hcp Fe at ambient and hydrostatic pressure conditions, contributing largely to the development of accurate thermodynamic modelling of Fe-based alloys.

  • 3.
    Holmström, Erik
    et al.
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden..
    Lizarraga, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Linder, David
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Salmasi, Armin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Wang, Wei
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Kaplan, Bartek
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden..
    Mao, Huahai
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Thermocalc Software AB, Rasundavagen 18, SE-16967 Solna, Sweden..
    Larsson, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Thermocalc Software AB, Rasundavagen 18, SE-16967 Solna, Sweden..
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. ppsala Univ, Div Mat Theory, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden.;Wigner Res Ctr Phys, Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary..
    High entropy alloys: Substituting for cobalt in cutting edge technology2018Ingår i: Applied Materials Today, ISSN 2352-9407, Vol. 12, s. 322-329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cemented carbide, also known as hard metal, is one of the most outstanding composite engineering materials since its commercial introduction in the 1920s. The unique combination of strength, hardness and toughness makes cemented carbides highly versatile materials for the most demanding engineering applications. In their simplest form, these materials are composites of tungsten carbide (WC) grains that are cemented with a ductile metallic binder phase, typically cobalt. However, despite the superiority of Co as binder material, there is a long-standing need to find alternative binders due to serious health concerns that have haunted the industry for nearly 80 years. In the present study, we develop a new cemented carbide with a high entropy alloy binder phase (CoCrFeNi) from raw materials to a fully functional, coated and gradient-sintered cutting tool insert. The new hard metal with reduced Co content is designed by using first principles theory and the CALPHAD method. The cutting tool was made by pressing the new hard metal in a standard geometry, sintered to have a thin binder phase enriched surface zone, free from cubic carbides and coated with protective layers of Ti(C,N) and Al2O3. The resulting cutting insert was tested in a real machining operation and compared to a state-of-the-art reference that had Co as binder phase. The cutting tool made of the newly developed cemented carbide has an exceptionally high resistance against plastic deformation at all tested cutting speeds in the machining test, outperforming the reference insert, which shows a linear increase in edge depression when the cutting speed is increased. This result opens up the possibility to utilize the unique properties of high entropy alloys for industrial applications, in particular, as binder phase in new cemented carbides.

  • 4.
    Lamelas, Victor
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer.
    Tian, Liyun
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Bonvalet-Rolland, Manon
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer. UMET, Unité Matériaux et Transformations, Université de Lille, CNRS, INRAe, Centrale Lille, UMR 8207, 59000, Lille, France.
    Walbrühl, M.
    AB Sandvik Coromant R&D, Lerkrogsvägen 19, SE-126 80 Stockholm, Sweden.
    Lizarrága, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Borgenstam, Annika
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Strukturer.
    Modeling of the intrinsic softening of γ-carbides in cemented carbides2023Ingår i: Materials Today Communications, ISSN 2352-4928, Vol. 37, artikel-id 107454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cemented carbides are widely used materials in industrial applications due to their remarkable combination of hardness and toughness. However, they are exposed to high temperatures during service leading to a reduction of their hardness. A common practice to damp this softening is to incorporate transition metal carbides in cemented carbide compositions, which keeps the hardness relatively higher when temperature increases. Understanding the underlying mechanisms of this softening is crucial for the development of cemented carbides with optimal properties. In this work, atomic-scale mechanisms taking place during plastic deformation are analyzed and linked to the effect that they have on the intrinsic macro-scale softening of the most common TMC used in cemented carbides grades (TiC, ZrC, HfC, VC, NbC and TaC). The proposed model uses the generalized stacking fault energy obtained from density functional theory calculations as an input to Peierls-Nabarro analytical models to obtain the critically resolved shear stress needed for deformation to occur in different slip systems. Subsequently, this information is used to predict the hardness variation across the temperature service range experienced by cemented carbides in wear applications. In addition to the prediction of hot-hardness for TMC, the obtained results also offer valuable insights into the intrinsic mechanisms governing TMCs deformation. The results facilitate the identification of dominant dislocation types influencing plasticity within distinct temperature regimes, define energetically favorable slip systems, and predict the brittle-ductile transition temperature in these materials. For instance, for group IV carbides at low temperatures, the slip system with a lower GSFE is {110}<11̅0> and around 30% of their melting temperature, the GSFE of partial slip in {111}<12̅1> becomes lower, changing the dominant slip mechanism and characterizing the Brittle-Ductile transition.

  • 5.
    Lattemann, Martina
    et al.
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden..
    Xie, Ruiwen
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Lizarraga, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala Univ, Div Mat Theory, Dept Phys & Astron, POB 516, SE-75120 Uppsala, Sweden.;Wigner Res Ctr Phys, Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary..
    Holmström, Erik
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden..
    Understanding Quality Control of Hard Metals in Industry - A Quantum Mechanics Approach2019Ingår i: Advanced Theory and Simulations, E-ISSN 2513-0390, Vol. 2, nr 6, artikel-id 1900035Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For many decades, the magnetic saturation of, for example, hard metals (HM) such as WC-Co-based cemented carbides, has been used as process and quality control in industry to ensure consistency of product properties. In an urge to replace cobalt as a binder phase, a demand on understanding the magnetic response as a function of composition on the atomic scale is growing. In this paper, a theoretical description of the measured weight-specific magnetic saturation of hard metals as a function of the tungsten weight fraction present in the cobalt binder phase, based on first-principle calculations, is established for standard WC-Co. The predicted magnetic saturation agrees well with the experimental one. Furthermore, it is proposed that the theoretical description can be extended to alternative and more complex binder phases which allows to transfer the production control to those hard metals.

  • 6.
    Li, Xiaoqing
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Wei, Daixiu
    Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai, Miyagi 980-8577, Japan.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Lizarrága, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Micro-mechanical properties of new alternative binders for cemented carbides: CoCrFeNiWx high-entropy alloys2020Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 820, artikel-id 153141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-entropy alloys are a new type of materials with excellent properties that offer a great variety of possibilities due to the large degree of freedom in element composition. In particular, CoCrFeNiW alloys have recently attracted a lot of attention due to their potential use in solving the long-standing problem of substituting cobalt in the cemented carbide industry. The lack of experimental and theoretical studies on these multi-components alloys hinders their optimal development. In this work, we aim at filling in this gap by studying their mechanical properties employing first-principles alloy theory and experimental techniques. By using the calculated elastic parameters, we analyzed the mechanical stability, elastic anisotropy, Debye temperature, and derived polycrystalline moduli. Moreover, we fabricated CoCrFeNi and (CoCrFeNi)0.96W0.04 and analyzed them by means of X-ray diffraction and electron backscatter diffraction. The hardness and the Young's modulus were measured. The Young's moduli and the lattice parameters were compared to first principles calculations and good agreement was obtained. Hardness increases with the increment of W composition.

  • 7.
    Lizarraga, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Universidad Austral de Chile, Chile.
    Structural and magnetic properties of the Gd-based bulk metallic glasses GdFe2, GdCo2, and GdNi2 from first principles2016Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 94, nr 17, artikel-id 174201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A structural and magnetic characterization of Gd-based bulk metallic glasses, GdFe2, GdCo2, and GdNi2, was performed. Models for the amorphous structures for two magnetic configurations, ferromagnetic and ferrimagnetic, were obtained by means of a first-principles-based method, the stochastic quenching. In all three cases, the ferrimagnetic configuration was energetically more stable than the ferromagnetic one, in perfect agreement with experiments. In the structural analysis, radial and angle distribution functions as well as calculations of bond lengths and average coordination numbers were included. Structural properties are in good agreement with experiments and do not depend on the magnetic configuration. The distribution of magnetic moments shows that amorphous GdFe2 and GdCo2 are both ferrimagnets, with antiparallel alignment of the magnetic moments of the two magnetic sublattices, whereas Ni nearly loses its magnetic moment in amorphous GdNi2, similar to the situation in its crystalline counterpart.

  • 8.
    Lizarraga, Raquel
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Holmstrom, Erik
    Sandvik Coromant R&D, SE-12680 Stockholm, Sweden..
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala Univ, Div Mat Theory, Dept Phys & Astron, Box 516, SE-75121 Uppsala, Sweden.;Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary..
    Alloying effect of tungsten on the structural and magnetic properties of CoCrFeNiW high entropy alloys2018Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 2, nr 9, artikel-id 094407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent observation of the hexagonal-closed-packed (hcp) phase in CoCrFeNi-based multicomponent alloys has reopened the question of phase stability in these alloys. We investigate the alloying effect of tungsten on the crystal and magnetic structures of (CoCrFeNi)(1-x)W-x high entropy alloys using density functional theory by means of the exact muffin-tin orbital method. The body-centered-cubic (bcc), face-centered-cubic (fcc), and hcp phases are investigated in two magnetic states: ferrimagnetic and paramagnetic. Below 8 at. % W the ground state of (CoCrFeNi)(1-x)W-x is the ferrimagnetic hcp phase and above that, the ferrimagnetic bcc phase is stabilized. Our calculations show that the fcc and hcp phases are energetically very close in the whole range of studied W compositions and because CoCrFeNi and (CoCrFeNi)(0.93)W-0.07 are observed in the fcc phase at room temperature, the hcp-fcc structural phase transition is expected to occur at lower temperatures. The total magnetic moment in bcc is almost double the value calculated for the fcc and hcp structures, which is due to that Cr moments are nearly quenched in bcc but are coupled antiferromagnetically to Fe, Ni, and Co in both hcp and fcc. We calculated also the Curie temperature of these alloys using the mean-field approximation. The calculated value was found to be 155 K for fcc CoCrFeNi, in excellent agreement with experiments, and the addition of W decreases this value. Our results contribute to the development of these relatively unknown corrosion-resistant materials into industrial applications, such as cemented carbides.

  • 9.
    Lizarraga, Raquel
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Pan, Fan
    KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Bergqvist, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Holmstrom, Erik
    Gercsi, Zsolt
    Vitos, Levente
    First Principles Theory of the hcp-fcc Phase Transition in Cobalt2017Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 7, artikel-id 3778Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Identifying the forces that drive a phase transition is always challenging. The hcp-fcc phase transition that occurs in cobalt at similar to 700 K has not yet been fully understood, although early theoretical studies have suggested that magnetism plays a main role in the stabilization of the fcc phase at high temperatures. Here, we perform a first principles study of the free energies of these two phases, which we break into contributions arising from the vibration of the lattice, electronic and magnetic systems and volume expansion. Our analysis of the energy of the phases shows that magnetic effects alone cannot drive the fcc-hcp transition in Co and that the largest contribution to the stabilization of the fcc phase comes from the vibration of the ionic lattice. By including all the contributions to the free energy considered here we obtain a theoretical transition temperature of 825 K.

  • 10.
    Lizarrága, Raquel
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Department of Industrial Production, Royal Institute of Technology, Stockholm SE-100 44, Swede.
    Li, Xiaojie
    Taizhou Univ, Dept Phys, Taizhou 318000, Peoples R China..
    Wei, Daixiu
    Tohoku Univ, Inst Mat Res, 2-1-1 Katahira, Sendai, Miyagi 9808577, Japan..
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Uppsala Univ, Div Mat Theory, Dept Phys & Mat Sci, POB 516, SE-75120 Uppsala, Sweden. Res Inst Solid State Phys & Opt, Wigner Res Ctr Phys, POB 49, H-1525 Budapest, Hungary..
    Li, Xiaoqing
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    The effect of Si and Ge on the elastic properties and plastic deformation modes in high- and medium-entropy alloys2021Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 119, nr 14, s. 141904-, artikel-id 141904Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We employ quantum mechanics modeling to investigate the effects of Ge and Si solute elements on the elastic properties and plastic deformation modes in two families of high-entropy alloys, CoCrFeMnNi and CoCrFeNi, and medium-entropy alloy, CoCrNi. The static lattice constants and single-crystal elastic parameters are calculated for these three face-centered-cubic random solid solutions as a function of composition. Using the elastic constants, we analyzed mechanical stability, derived polycrystalline modulus, and evaluated solid-solution strengthening for these multi-component alloys. We fabricated (CoCrFeNi)(100-x) Si-x (x = 0, 4, 6) and measured the polycrystalline modulus and hardness. The calculated trends for Young's and shear modulus as well as lattice parameters were verified by our measurements. The dependence of generalized stacking fault energy on Ge and Si was studied in detail for the considered multi-component alloys. The competition between various plastic deformation modes was revealed based on effective energy barriers. Our calculations predict that the activated deformation modes in all the alloys studied here are the stacking fault mode (dominant) and the full-slip mode (secondary), and as the concentrations of Ge and Si increase, twining becomes favored.

  • 11.
    Tian, Liyun
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Lizárraga, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Larsson, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Holmström, E.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Uppsala University, Sweden.
    A first principles study of the stacking fault energies for fcc Co-based binary alloys2017Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 136, s. 215-223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stacking fault energy is closely related to structural phase transformations and can help to understand plastic deformation mechanisms in materials. Here we perform first principles calculations of the stacking fault energy in the face centered cubic (fcc) Cobalt-based binary alloys Co1−x Mx, where M = Cr, Fe, Ni, Mo, Ru, Rh, Pd and W. We investigate the concentration range between 0 and 30 at.% of the alloying element. The results are discussed in connection to the phase transition between the low-temperature hexagonal close packed (hcp) and the fcc structures observed in Co and its alloys. By analyzing the stacking fault energies, we show that alloying Co with Cr, Ru, and Rh promotes the hcp phase formation while Fe, Ni and Pd favor the fcc phase instead. The effect of Mo and W on the phase transition differs from the other elements, that is, for concentrations below 10% the intrinsic stacking fault energy is lower than that for pure fcc Co and the energy barrier is higher, whereas above 10% the situation reverses. We carry out also thermodynamic calculations using the ThermoCalc software. The trends of the ab initio stacking fault energy are found to agree well with those of the molar Gibbs energy differences and the phase transition temperature in the binary phase diagrams and give a solid support for the phase stability of these alloys.

  • 12.
    Tian, Liyun
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Astron, Div Mat Theory, Box 516, SE-75120 Uppsala, Sweden..
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Uppsala Univ, Dept Phys & Astron, Div Mat Theory, Box 516, SE-75120 Uppsala, Sweden.;Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Lizarrága, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Temperature effects on the elastic and thermodynamic properties of Al1-xLix and Al1-xCrx alloys from first principles2021Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 5, nr 6, artikel-id 063604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal effects on the elastic and thermodynamic properties of face-centered cubic (fcc) Al-Li and Al-Cr alloys are investigated here by means of density-functional theory. We calculate the polycrystalline Young's modulus, Poisson's ratio, bulk modulus and shear modulus as a function of alloying concentration and temperature. The calculated elastic and thermodynamic properties are in good agreement with available experimental data. Increasing temperature lowers the values of the moduli of both alloys. The results show that both alloying elements increase the Young's modulus. In the case of Al-Li alloys, below 8 at.% Li the Young's modulus increases due to solid solution formation. Further improvement of the stiffness at higher concentrations is due to formation of precipitates. Cr increases almost linearly the Young's modulus, which at 10 at.% Cr becomes almost 34% higher than that of pure Al. The formation of precipitates do not affect the value of the elastic moduli at low Cr concentrations. We estimate the solid solution hardening effect in these alloys by combining the Labusch-Nabarro theory with density-functional theory data.

  • 13.
    Wang, Wei
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Dept Chemical Engineering, Northeast Electric Power University, Jilin, 132012, China.
    Hou, Ziyong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Lizarrága, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Tian, Ye
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Holmström, Erik
    Coromant R & D, SE-12680, Stockholm, Sweden.
    Mao, Huahai
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Thermo-Calc Software, Råsundav. 18, SE-16767, Solna, Sweden.
    Larsson, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Thermo-Calc Software, Råsundav. 18, SE-16767, Solna, Sweden.
    An experimental and theoretical study of duplex fcc+hcp cobalt based entropic alloys2019Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 176, s. 11-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Martensitically formed duplex fcc + hcp Co-based entropic alloys have been investigated both experimentally and theoretically. Theoretical predictions are in good agreement with experimental observations. A fair correlation is found between calculated driving forces for a partitionless fcc→hcp transformation and experimentally obtained phase fractions.

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  • 14.
    Xie, Ruiwen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Lizárraga, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Linder, David
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hou, Ziyong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Ström, Valter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Lattemann, M.
    Holmström, E.
    Li, Wei
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Quantum mechanics basis of quality control in hard metals2019Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 169, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Non-destructive and reliable quality control methods are a key aspect to designing, developing and manufacturing new materials for industrial applications and new technologies. The measurement of the magnetic saturation is one of such methods and it is conventionally employed in the cemented carbides industry. We present a general quantum mechanics based relation between the magnetic saturation and the components of the binder phase of cemented carbides, which can be directly employed as a quality control. To illustrate our results, we calculate the magnetic saturation of a binder phase, 85Ni15Fe binary alloy, using ab-initio methods and compare the theoretical predictions to the magnetic saturation measurements. We also analyse interface and segregation effects on the magnetic saturation by studying the electronic structure of the binder phase. The excellent agreement between calculations and measurements demonstrates the applicability of our method to any binder phase. Since the magnetic saturation is employed to ensure the quality of cemented carbides, the present method allows us to explore new materials for alternative binder phases efficiently.

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