Understanding imprint formation, plastic instabilities and hardness evolutions in FCC, BCC and HCP metal surfaces

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388998%3A_____%2F21%3A00544732" target="_blank" >RIV/61388998:_____/21:00544732 - isvavai.cz</a>

Alternative codes found

RIV/49777513:23640/21:43962528

Result on the web

<a href="https://www.sciencedirect.com/science/article/pii/S1359645421005024" target="_blank" >https://www.sciencedirect.com/science/article/pii/S1359645421005024</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.actamat.2021.117122" target="_blank" >10.1016/j.actamat.2021.117122</a>

Result language

angličtina

Original language name

Understanding imprint formation, plastic instabilities and hardness evolutions in FCC, BCC and HCP metal surfaces

Original language description

Nanoindentation experiments in metal surfaces are characterized by the onset of plastic instabilities along with the development of permanent nanoimprints and dense defect networks. This investigation concerns massive molecular dynamics simulations of nanoindentation experiments in FCC, BCC and HCP metals using blunted (spherical) tips of realistic size, and the detailed comparison of the results with experimental measurements. Our findings shed light on the defect processes which dictate the contact resistance to plastic deformation, the development of a transitional stage with abrupt plastic instabilities, and the evolution towards a self-similar steady-state characterized by the plateauing hardness at constant dislocation density . The onset of permanent nanoimprints is governed by stacking fault and nanotwin interlocking, the buildup of nanostructured regions and crystallites throughout the imprint, the cross-slip and cross-kinking of surfaced screw dislocations, and the occurrence of defect remobilization events within the plastic zone. As a result of these mechanisms, the ratio between the hardness and the Young's modulus becomes higher in BCC Ta and Fe, followed by FCC Al, HCP Mg and large stacking fault width FCC Ni and Cu. Finally, when nanoimprint formation is correlated with the uniaxial response of the indented minuscule material volume, the hardness to yield strength ratio, , varies from 7 to 10, which largely exceeds the continuum plasticity bound of 2.8. Our results have general implications to the understanding of indentation size-effects, where the onset of extreme nanoscale hardness values is associated with the occurrence of unique imprint-forming processes under large strain gradients.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

20301 - Mechanical engineering

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

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

Name of the periodical

Acta Materialia

ISSN

1359-6454

e-ISSN

1873-2453

Volume of the periodical

217

Issue of the periodical within the volume

September

Country of publishing house

GB - UNITED KINGDOM

Number of pages

14

Pages from-to

117122

UT code for WoS article

000691327100002

EID of the result in the Scopus database

2-s2.0-85111040252