Sep 7 2020
At the Skolkovo Institute of Science and Technology (Skoltech), researchers have proposed new hard and super hard ternary compounds present in the tungsten-molybdenum-boron system with the help of computational techniques.
Ternary phase diagram of the W-Mo-B system at 0 K. Image Credit: A. Kvashnin et al./Chemistry of Materials.
This was achieved in collaboration with the Institute of Solid State Chemistry and Mechanochemistry (ISSC SB RAS), Pirogov Medical University, as well as Yerevan State University. The study was recently published in the Chemistry of Materials journal.
Alexander Kvashnin, a senior research scientist at Skoltech and a co-author of the study, thinks that the study is a natural follow-on to prolonged studies into binary systems.
In finding new materials, the researchers had to make a more complex system by incorporating a third element, which led to new compounds and heavily modified properties. Such variations were the area of interest for the researchers.
The researchers hypothesized the structure of possibly superhard ternary compounds in the W-Mo-B system with the help of the USPEX evolutionary algorithm that was designed by Artem Oganov, a Skoltech professor and another co-author of the study, together with his students.
We planned to predict a series of ternary compounds that would display better mechanical properties, such as hardness and fracture resistance, as compared to binary compounds. We did predict several ternary compounds which turned out to be high-entropy alloys. The mixing of tungsten and molybdenum atoms produced compounds that were disordered and, therefore, had varying stability depending on temperature.
Alexander Kvashnin, Senior Research Scientist, Skolkovo Institute of Science and Technology
In general, carbides—compounds with four or five components—are categorized as high-entropy compounds. The researchers think that their research is the initial step toward determining such compounds among boride systems.
Obvious prospects of this research may translate into new hard materials outperforming their existing counterparts and withstanding higher temperatures or pressures. Companies such as Gazpromneft may use those materials for drilling or other purposes.
Christian Tantardini, Study Author, Skolkovo Institute of Science and Technology
Tantardini is also an employee of ISSC. The researchers plan to follow their research efforts. They are keen to discover what happens to much more complex compounds when there are changes in pressure and temperature.
Journal Reference
Kvashnin, A. G., et al. (2020) Computational Search for New W-Mo-B Compounds. Chemistry of Materials. doi.org/10.1021/acs.chemmater.0c02440.