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Nanoindentation of a Pseudoelastic NiTiFe Shape Memory Alloy
Author(s) -
PfetzingMicklich Janine,
Wagner Martin FranzXaver,
Zarnetta Robert,
Frenzel Jan,
Eggeler Gunther,
Markaki Athina Emmanuel,
Wheeler Jeff,
Clyne Trevor William
Publication year - 2010
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.200900266
Subject(s) - nanoindentation , materials science , shape memory alloy , pseudoelasticity , indentation , plasticity , austenite , martensite , creep , composite material , phase (matter) , diffusionless transformation , deformation (meteorology) , metallurgy , microstructure , chemistry , organic chemistry
Nanoindentation is a suitable tool for characterizing the local mechanical properties of shape memory alloys (SMA) and to study their pseudoelastic behavior. There is a special interest in indenting with different indenter tips (as not all tips are associated with strain states that predominantly induce the martensitic transformation) and in indenting at different temperatures, where different phases are present. In this study, we perform nanoindentation on a ternary NiTiFe SMA with different indenter tips and at various testing temperatures. For nanoindentation with spherical tips, load–displacement hystereses clearly indicate pseudoelastic behavior, whereas indentation with Berkovich tips results in more pronounced plastic deformation. Testing at different temperatures is associated with different volume fractions of austenite, martensite, and R‐phase. The corresponding nanoindentation responses differ considerably in terms of pseudoelastic behavior. Best pseudoelastic recovery is found at testing temperatures close to the R‐phase start temperature, even though this temperature is below the austenite finish temperature, which is a well‐known lower temperature bound for full recovery in macroscopic tests. Our results are discussed considering micromechanical aspects and the interaction between stress‐induced phase transformation and dislocation plasticity.