| Autor: |
Xueling Fei, O'Connell, Corey J., Grummon, D. S., Yang-Tse Cheng |
| Předmět: |
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| Zdroj: |
Journal of Materials Science; Dec2011, Vol. 46 Issue 23, p7401-7409, 9p, 1 Black and White Photograph, 4 Diagrams, 4 Charts, 6 Graphs |
| Abstrakt: |
Indentation-induced two-way shape memory leads to pronounced temperature dependence of the depth of spherical indents made in martensitic NiTi shapememory alloys. They are shallower when austenitic, and depth varies during both M → A and A → M transformations. If the impression is planarized, by metallographic grinding at Tf, a protrusion rises at the site when warmed past Af. If cooled again this ''exdent'' retreats, restoring optical flatness. The cycle is repeatable, and exdent heights can exceed 15% of prior indent depth. Since it maps between macroscopically distinguishable topographies, or forms, at orders greater length scale than the surface roughness, we call the effect ''surface form memory''-SFM. Notable regarding potential applications is that, when loaded in compression by planar contact with a strong base metal, exdents exert sufficient pressure to indent the latter, suggesting that subsurface transformational mechanisms operate at volumetric work-energy densities >107 J/m3, fully ∼10% of the M → A enthalpy. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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