Berkovich nanoindentation on single SiGe epitaxial films

Duan, Lian; Lin, Pei Li

doi:10.1016/j.microrel.2015.11.001

Cited by 8 publications

(2 citation statements)

References 29 publications

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“…Interesting was the shape evolution of the corresponding P-h curves (Figure 37a): while the second cycle exhibited a steeper slope corresponding to the highest hardness value, the P-h curves of the subsequent cycles, correlated with supereleastic behavior, exhibited a kink in their slope, similar to the elbows reported elsewhere [190][191][192][193][194][195][196][197][198] . Pan et al did not mention this issue, however within the scope of the present thesis the origin of these elbows is discussed.…”

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confidence: 72%

“…Kinks observed in the present study are designated in literature as elbows, and they are regularly observed in nanoindentation curves of Si and other semiconductors. They have been related to reversible amorphization under load [196][197][198] , annealing treatments 195 , and also to reversible phase transformation [190][191][192][193] . Also polymers and gold were found to exhibit elbows related to phase transformation 194 .…”

Section: Evaluation Of Elbow Formation In Cyclic P-h Curves Under Loa...mentioning

confidence: 99%

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Deformation mechanisms of metastable stainless steels accessed locally by monotonic and cyclic nanoindentation

Sapezanskaia

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Metastable austenitic stainless steels feature an abundance of different deformation mechanisms, which contribute to the distinguished mechanical properties of these alloys. However, these properties are known to depend on the local microstructure and also are highly anisotropic. Furthermore, deformation is expected to be different for the bulk and the surface of a sample. In this sense, a discrete study is not trivial. The present work aims at investigation of the main deformation mechanisms and their gradual evolution, by employing controlled deformation of individual austenite grains via monotonic and cyclic nanoindentation. The corresponding loading–unloading curves have given extensive information about underlying mechanical properties, which could be related to an exhaustive reconstruction of the deformation substructure, both in surface and bulk, by different small scale characterization techniques. Amongst others, features such as time-dependent deformation, reversible phase transformation under load, crystalline anisotropy and grain size influences, besides plasticity transmission and fatigue behavior have been found and analyzed. Los aceros inoxidables austeníticos metaestables pueden experimentar una amplia gama de mecanismos de deformación diferentes, los cuales contribuyen a sus extraordinarias propiedades mecánicas. Sin embargo, estas propiedades dependen de la microestructura y son altamente anisotrópicas. Además, la deformación es diferente en la superficie y en el interior de una muestra. Por lo tanto, un estudio detallado no resulta trivial. El objetivo de este trabajo es el estudio de los principales mecanismos de deformación, así como de su desarrollo gradual. Para ello se han realizado ensayos de nanoindentación, tanto monotónica como cíclica, los cuales han permitido la deformación controlada de granos austeníticos preseleccionados. Las curvas de carga y descarga de los ensayos de nanoindentación han proporcionado amplia información sobre el comportamiento mecánico del acero, la cual se ha podido correlacionar con la reconstrucción detallada de las subestructuras de deformación, tanto a nivel superficial como en el interior, la cual se ha llevado a cabo mediante técnicas de caracterización a escala microscópica. Entre otros, se encontraron y estudiaron fenómenos como las transformaciones de fase reversibles bajo carga, la influencia tanto de la anisotropía cristalina como del tamaño de grano, mecanismos dependientes del tiempo, junto con la transmisión de plasticidad y la respuesta a fatiga. Les aciers inoxydables austénitiques métastables sont le siège de différents mécanismes de déformation qui sont à l'origine des propriétés mécaniques qui distinguent ce type d’alliages. Cependant, ces dernières, dépendant de la microstructure locale, sont fortement anisotropes. Par ailleurs, la déformation d'un échantillon massif serait différente de celle obtenue en surface. De ce fait, une étude détaillée trouve tout son intérêt. Le présent travail vise donc à identifier les principaux mécanismes de déformation et de leur évolution progressive, en se basant sur une déformation contrôlée de grains austénitiques individuels par des tests mécaniques de nanoindentation monotoniques et cycliques. Les courbes correspondantes au chargement-déchargement révèlent des informations détaillées sur les propriétés mécaniques sous-jacentes qui pourraient être liées à une étude complète de la structure de déformation en surface et en volume par différentes techniques de caractérisation à une échelle très fine. La déformation en fonction du temps, les phénomènes de transformation de phase réversible sous charge, l'anisotropie cristalline, l'influences de la taille des grains, la transmission de la plasticité et la tenue en fatigue ont été mis en évidence et étudiés.

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confidence: 72%

Section: Evaluation Of Elbow Formation In Cyclic P-h Curves Under Loa...mentioning

confidence: 99%

Deformation mechanisms of metastable stainless steels accessed locally by monotonic and cyclic nanoindentation

Sapezanskaia

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Reversible Phase Transformation in Polycrystalline TRIP Steels Induced by Cyclic Indentation Performed at the Nanometric Length Scale

Rovira

Sapezanskaia

Fargas

et al. 2018

steel research int.

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Metastable austenitic stainless steels are an interesting group of materials, which exhibit the Transformation Induced Plasticity effect. In this regard, phase transformation from austenite to martensite enhances the work hardening of the metastable austenitic stainless steels affecting the deformation dynamics and mechanical properties including fatigue properties. Within this context, the reversible load-induced phase transformation from γ to e-martensite is investigated at the local scale under cyclic indentation. This reversible phase transformation is manifested itself by a combination of hysteresis loops, elbow formation, and reversible pop-ins in the loading curve. The initial cyclic achieved through the nanoindentation technique allows to identify three different deformation regimes for the <111> austenitic grains. Firstly, a softening effect takes place due to the dislocation activation; subsequently the phase transformation induces a hardening effect and finally, the load deformation curve reaches a plateau where no more plastic deformation is observed. Experimental Section

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