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Exceptional crystal strain hardening determined over macro- to micro- to nano-size scales in continuous spherical indentation tests.
- Source :
-
Materials Science & Engineering: A . May2019, Vol. 757, p95-100. 6p. - Publication Year :
- 2019
-
Abstract
- Calculations of an order of magnitude greater strain hardening coefficient over compression or tensile test measurements are demonstrated for continuous indentation hardness measurements past "pop-in". Analyses were performed at small indentation strains for a macro-ball test on a NaCl crystal and at larger strains measured for rounded points of micro- and nano-tipped indenters in tests of MgO and copper crystal surfaces. The exceptional strain hardening is attributed to the smaller spacing and consequent interactions of the plastically-induced dislocations, including for MgO, the formation of nano-scale sessile dislocations accompanying the imposed three-dimensional deformation. The dislocation-based hardening is much greater than the smaller so-called "Indentation Size Effect (ISE)" of softening obtained at larger, constant strain, penetration depths with Berkovich-type indenters. Such ISE softening is attributed rather to the reverse effect of increasingly larger dislocation separations accompanying the greater plastic indentation depths. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09215093
- Volume :
- 757
- Database :
- Academic Search Index
- Journal :
- Materials Science & Engineering: A
- Publication Type :
- Academic Journal
- Accession number :
- 136560787
- Full Text :
- https://doi.org/10.1016/j.msea.2019.04.090