EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Since the discovery of magnetic skyrmions in the B20 compound MnSi [1], there has been a significant interest in the magnetic properties of this and other B20 compounds. Many experimental and theoretical studies addressed the effect of transition metal doping and one of the interesting observations was the emergence of skyrmions in an alloy of non-magnetic FeSi and CoSi [2].

In this work,...

Extensive modelling efforts have been devoted to the understanding of thermodynamics and diffusion in the fcc Fe-Ni system, which has a complicated magnetochemical phase diagram. However, the effects of magnetic excitations and transitions on these properties are unclear and usually neglected. Furthermore, a close interplay between the magnetic and chemical degrees of freedom is also expected,...

MIL-101(Cr) is one of the metal organic frameworks (MOFs) that has been successfully applied to gas/solute separation1 and catalysis2 because of its large specific surface area, pore accessibility and noticeable chemical and solvent stability.1 It has been modified in many studies to enhance its efficiency for customized applications. The modifications range from combination with other...

High-performance permanent magnets are needed for a large number of applications, especially ‘green’ energy conversion, such as electric motors and windmills, which require them in extremely large quantities. At the same time, the heavier rare-earth elements which are necessary for obtaining the good magnetic characteristics of these materials are often mined with methods that leave an...

The small-polaron hopping model has been used for several decades for modeling electronic charge transport in oxides. Despite its significance, the model was developed for binary oxides, and its accuracy has not been rigorously tested for higher-order oxides. To investigate this issue, we chose the MnxFe3-xO4 spinel system, which has exciting electrochemical and catalytic properties, and mixed...

Motivated by a recently reported martensitic transformation in the TiAl+Mointermetallic system, Density Functional Theory (DFT) has been used to investigate compositional trends in structural and mechanical properties of this model alloy system. Namely, two ordered phases, cubicβoand orthorhombicB19 (representing the fully ordered hexagonal phase), one hexagonal partially ordered...

Displacive solid-state phase transformations from the face centered cubic (fcc) austenite phase (γ) to body centered cubic (bcc) ferrite phase (α) play a pivotal role in the physical properties of steels and ferrous alloys. The rapid change in crystal structure inherently alters the mechanical properties of these materials, including fatigue, plasticity and strength [1,2].
In this work,...

Due to their good combination of properties such as strength and hardness, martensitic steels are extensively used in industry and the technological sector since many years. Despite its long history of usage and application, several phenomena observed and processes happening in martensitic steels are insufficiently understood, and hence are open questions in materials science.
When...

Several studies emphasise the impact of vacancies and impurities leading to severe degradation effects that have been observed experimentally in metals. To fully understand these effects first principle approaches are usually employed. However, such methods are constrained due to their computational cost and cannot simulate systems with more than 1000 atoms. On the other hand, interatomic...

In the present study, we employ a QM/MM approach, which couples DFT and MD to overcome limits inherent to both of the methods. The coupled algorithm is used to study interfaces at an atomistic level. While MM is applied to (chemically and structurally simpler) matrix regions, QM is used to treat chemical impurities and extended defects such as interfaces.

After introducing the methodology,...

High entropy alloys have attracted considerable attention in the past decade due to their excellent mechanical properties and thermal stability which often exceed values of those of their constituting species as well as commonly investigated intermetallic phases. Titanium aluminides are a class of light-weight high-temperature structural materials with excellent mechanical properties and a...

Recent developments in machine learning techniques has immensely benefited ab initio modeling of materials. Interatomic potentials such as the moment tensor potential (MTP) (Shapeev, 2016) that are trained to high temperature density-functional theory (DFT) data are able to predict energies and forces of atomic configurations highly accurately. They are thus able to statistically sample a...

Multi-principal element alloys (MPEAs) consist of four or more elements alloyed in approximately equal fractions and often crystallize in a simple crystal lattice. In many cases, their mechanical properties like structural stability or ductility exceed that of common modern alloys. Usually they contain transition or refractory metals whose bonds are dominated by their d-electrons. Up to now,...

Phase field crystal simulation of the structure transformation from cubic to hexagonal phase and its verification in TiAlN coating

Yi Kong, Chenshuang Wei, Xiong Shuai, Hong Mao, Li Chen, Sai Tang, Yong Du

State Key Lab of Powder Metallurgy, Central South University, Changsha 410083, China

Abstract:

TiAlN-based coatings have been extensively used as a protective layer for tools in...

Structures of amorphous CNx, SiCN, BCN and SiBCN materials are predicted by extensive ab-initio molecular-dynamics simulations (over 10 000 trajectories) in a wide range of compositions and densities [1,2]. When and only when the structures are allowed to include unbonded N2 molecules, the predicted lowest-energy densities are in agreement with the experiment. The main attention is paid to the...

Alloys of light main group elements are attractive due to a unique combination of properties ranging from high hardness through optical transparency to high temperature stability and oxidation resistance. The properties, in the first place electrical conductivity, can be further modulated by addition of early transition metals. Amorphous Hf(M)SiBCN thin films are investigated by combining...