Unprecedented plastic flow channel in gamma-B-28 through ultrasoft bonds: A challenge to superhardness

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27740%2F18%3A10241966" target="_blank" >RIV/61989100:27740/18:10241966 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.researchgate.net/publication/329634776_Unprecedented_plastic_flow_channel_in_g_-_B_28_through_ultrasoft_bonds_A_challenge_to_superhardness" target="_blank" >https://www.researchgate.net/publication/329634776_Unprecedented_plastic_flow_channel_in_g_-_B_28_through_ultrasoft_bonds_A_challenge_to_superhardness</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevMaterials.2.123602" target="_blank" >10.1103/PhysRevMaterials.2.123602</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Unprecedented plastic flow channel in gamma-B-28 through ultrasoft bonds: A challenge to superhardness

Popis výsledku v původním jazyce

A longstanding controversy remains whether gamma-B-28 is intrinsically superhard or not, i.e., H-upsilon &gt;= 40 GPa. Here we perform comprehensive investigations on the mechanical properties of gamma-B-28 to reveal the plasticity and failure mode of gamma-B-28 through the unique combination of microindentation experiment, the ideal strength approach, and the ab initio informed Peierls-Nabarro model. A low load-invariant hardness of similar to 30 GPa is found for both polycrystalline and monocrystalline gamma-B-28. By carefully checking the strength anisotropy and strain facilitated phonon instability, a surprising ideal strength of 23.1 GPa is revealed along the (001)[010] slip system for gamma-B-28, together with an inferior Peierls stress of 3.2 GPa, both of which are close to those of B6O and ZrB12 yet much lower than those of diamond and c-BN. These results suggest that gamma-B-28 could not be intrinsically superhard. Atomistic simulation and electronic structure analysis uncover an unprecedented plastic flow channel through the specific ultrasoft bonding, which causes a dramatic softening of gamma-B-28. These findings highlight an approach to quantifying the realistic hardness by means of two plasticity descriptors beyond the elastic limit, i.e., the ideal strength approach and the Peierls-Nabarro model.

Název v anglickém jazyce

Unprecedented plastic flow channel in gamma-B-28 through ultrasoft bonds: A challenge to superhardness

Popis výsledku anglicky

A longstanding controversy remains whether gamma-B-28 is intrinsically superhard or not, i.e., H-upsilon &gt;= 40 GPa. Here we perform comprehensive investigations on the mechanical properties of gamma-B-28 to reveal the plasticity and failure mode of gamma-B-28 through the unique combination of microindentation experiment, the ideal strength approach, and the ab initio informed Peierls-Nabarro model. A low load-invariant hardness of similar to 30 GPa is found for both polycrystalline and monocrystalline gamma-B-28. By carefully checking the strength anisotropy and strain facilitated phonon instability, a surprising ideal strength of 23.1 GPa is revealed along the (001)[010] slip system for gamma-B-28, together with an inferior Peierls stress of 3.2 GPa, both of which are close to those of B6O and ZrB12 yet much lower than those of diamond and c-BN. These results suggest that gamma-B-28 could not be intrinsically superhard. Atomistic simulation and electronic structure analysis uncover an unprecedented plastic flow channel through the specific ultrasoft bonding, which causes a dramatic softening of gamma-B-28. These findings highlight an approach to quantifying the realistic hardness by means of two plasticity descriptors beyond the elastic limit, i.e., the ideal strength approach and the Peierls-Nabarro model.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physical Review Materials

ISSN

2475-9953

e-ISSN

—

Svazek periodika

2

Číslo periodika v rámci svazku

12

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

6

Strana od-do

—

Kód UT WoS článku

000452971600001

EID výsledku v databázi Scopus

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