Special Issue "Advances in Cermets"
A special issue of Metals (ISSN 2075-4701).
Deadline for manuscript submissions: 1 April 2014
Dr. Marta Ziemnicka-Sylwester
Faculty of Engineering, Hokkaido University, Kita 18, Nishi 8, 060- 8628, Sapporo, Japan
Website: http:// http://www.eng.hokudai.ac.jp/labo/MSESC/marta/?id=cv
Interests: ultra-high temperature materials; cermets; strengthening; hardness and fracture toughness; wear and corrosion resistance; combustion synthesis; sintering; powder metallurgy
Advanced technologies development requires foolproof materials with excellent wear resistance, hardness and fracture toughness. Cermets are ideally designed to combine the optimal properties of both high temperature resistant tough ceramics and ductile metals which possess the ability to reduce cracks propagations and prevent catastrophic failure. Therefore, much better reliability is expected from cermet composites than from any other particular components. Thanks to their superior qualities, cermets are important components in spacecrafts and rocket engines, cutting and drilling tools, fuselage of supersonic planes, combustors in flame vents, among many others.
The precise technology of fabrication is essential, since microstructure refinement and uniform distribution of matrix phase can significantly enhance fracture toughness. However, it is still a challenge for materials engineering to develop new cermets for more severe applications, with matrix phase consisting of ductile metal, rather than brittle intermetallics.
In this Special Issue on “Advances in Cermets” we are soliciting original experimental and theoretical papers, as well as comprehensive reviews which are focused on new and advanced cermets. The scope of this Special Issue covers a very broad range of topics from fundamental concepts, such as phase equilibrium in refractory metal-superhard ceramics systems, hardness and fracture toughness of metal matrix composites, creep and wear resistance, to recent advances in technology development for cemented carbides and borides.
Dr. Marta Ziemnicka-Sylwester
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed Open Access quarterly journal published by MDPI.
Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.
- metal matrix composites MMC
- technical ceramics
- cemented carbides
- fracture toughness
The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.
Type of Paper: Article
Title: Crystallization of Supercooled Liquid Elements Induced by Homogeneous Nucleation and Growth of Superclusters Containing Magic Atom Numbers
Author: Robert F. Tournier
Affiliation: CRETA/CNRS, Université Joseph Fourier, B.P. 166, 38042 Grenoble cedex 09, France
Abstract: An undercooled liquid gives rise to superclusters with icosahedral order, when the temperature decreases. They could be transformed in growth nuclei of crystallized phase. The intrinsic growth nuclei would contain stable magic atom numbers such as 13, 55, 147, 309 and 561 surviving in melts above the melting temperature Tm or being condensed by homogeneous nucleation. Surviving nuclei are known to texture materials by slow solidification between liquidus and solidus temperatures where crystals growing by heterogeneous nucleation still have easy-magnetization axis being free to align in magnetic field. Their existence raises numerous questions about our current understanding of the crystallization process. They survive in melts if all surface atoms have the same fusion heat than core atoms. The classical Gibbs free energy change from melt to crystal neglects the volume difference between liquid and solid which induces an enthalpy saving −Vm × Δp where Δp is the Laplace pressure change acting on the nucleus. An energy saving −εls ΔHm equal to −Vm × Δp per molar volume Vm is introduced in the volume energy where ΔHm is the fusion enthalpy of bulk materials while the surface energy is multiplied by (1 + εls). In liquid elements, these quantities are calculated by considering a virtual transfer of nΔz free electrons from a n-atom nucleus to melt equalizing their Fermi energies. The number nΔz of s-electrons bound to this spherical attractive potential is obtained when the potential energy associated with the critical radius R* at Tm is equal to the quantified solution of the Schrödinger equation εls0 × ΔHm = 0.217 × ΔHm in all liquid elements. The coefficient εnm of a n-atom cluster being a function of θ2 with θ = (T − Tm)/Tm and (dεls/dT)Tm = 0, any nucleus has the same fusion heat than a bulk sample as expected. The concept of homogeneous nucleation temperature is revised because a 13-atom cluster homogeneously condensed during cooling always reduces the critical energy barrier when its own barrier depending on nm and R authorizes it to grow beyond its own radius. The undercooling rate increases when the sample volume v decreases. The undercooling temperatures of 38 elements are predicted as a function of v in agreement with a lot of experimental results. The undercooling rates are smaller when intrinsic nuclei containing 55, 147, 309 and 561 atoms have not been melted above Tm by liquid homogeneous nucleation. The observed undercooling rates of Cr, Hg, V, Al, Cd and Sn are controlled by impurities and the theoretical values are much larger. Superclusters with magic atom numbers control the crystallization.
Last update: 23 December 2013