Details
| Original language | English |
|---|---|
| Title of host publication | Mechanically Active Materials |
| Publisher | Materials Research Society |
| Pages | 19-24 |
| Number of pages | 6 |
| ISBN (print) | 1558998071, 9781558998070 |
| Publication status | Published - 2004 |
| Externally published | Yes |
| Event | 2004 MRS Fall Meeting - Boston, MA, United States Duration: 29 Nov 2004 → 3 Dec 2004 |
Publication series
| Name | Materials Research Society Symposium Proceedings |
|---|---|
| Volume | 855 |
| ISSN (Print) | 0272-9172 |
Abstract
The objective of this study is to examine the effect of heat treatment on polycrystalline Ti50.9 at.%Ni subsequent to hot-rolling. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation processed NiTi. The results constitute a fundamental understanding of the effect of heat treatment on thermal/stress induced martensite, which is critical for optimizing mechanical properties. The high temperature of the hot-rolling process caused recrystallization, recovery, and hindered precipitate formation, essentially solutionizing the NiTi. Subsequent heat treatments were carried out at various temperatures for 1.5 hours. Transmission Electron Microscopy (TEM) observations revealed that Ti3NI4 precipitates progressively increased in size and changed their interface with the matrix from being coherent to incoherent with increasing heat treatment temperature. Accompanying the changes in precipitate size and interface coherency, transformation temperatures were observed to systematically shift, leading to the occurrence of the R-phase and multiple-stage transformations. Room temperature stress-strain tests illustrated a variety of mechanical responses for the various heat treatments, from pseudoelasticity to shape memory. The changes in stress-strain behavior are interpreted in terms of shifts in the primary martensite transformation temperatures, rather then the occurrence of the R-phase transformation. The results confirm that Ti 3Ni4 precipitates can be used to elicit a desired isothermal stress-strain behavior in polycrystalline NiTi.
ASJC Scopus subject areas
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
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Mechanically Active Materials. Materials Research Society, 2004. p. 19-24 (Materials Research Society Symposium Proceedings; Vol. 855).
Research output: Chapter in book/report/conference proceeding › Conference contribution › Research › peer review
}
TY - GEN
T1 - Thermal processing of polycrystalline NiTi shape memory alloys
AU - Frick, Carl P.
AU - Ortega, Alicia M.
AU - Tyber, Jeff
AU - Gall, Ken
AU - Maier, Hans J.
AU - Maksound, A. El M.
AU - Liu, Yinong
N1 - Funding Information: The U.S. authors gratefully thank financial support for this work from the Department of Energy through a Presidential Early Career Award for Scientists and Engineers (PECASE), as well as the Joint Institute for Laboratory Astrophysics (JILA) for use of their Atomic Force Microscope. The German authors gratefully thank financial support for this work from Deutsche Forschungsgemeinschaft.
PY - 2004
Y1 - 2004
N2 - The objective of this study is to examine the effect of heat treatment on polycrystalline Ti50.9 at.%Ni subsequent to hot-rolling. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation processed NiTi. The results constitute a fundamental understanding of the effect of heat treatment on thermal/stress induced martensite, which is critical for optimizing mechanical properties. The high temperature of the hot-rolling process caused recrystallization, recovery, and hindered precipitate formation, essentially solutionizing the NiTi. Subsequent heat treatments were carried out at various temperatures for 1.5 hours. Transmission Electron Microscopy (TEM) observations revealed that Ti3NI4 precipitates progressively increased in size and changed their interface with the matrix from being coherent to incoherent with increasing heat treatment temperature. Accompanying the changes in precipitate size and interface coherency, transformation temperatures were observed to systematically shift, leading to the occurrence of the R-phase and multiple-stage transformations. Room temperature stress-strain tests illustrated a variety of mechanical responses for the various heat treatments, from pseudoelasticity to shape memory. The changes in stress-strain behavior are interpreted in terms of shifts in the primary martensite transformation temperatures, rather then the occurrence of the R-phase transformation. The results confirm that Ti 3Ni4 precipitates can be used to elicit a desired isothermal stress-strain behavior in polycrystalline NiTi.
AB - The objective of this study is to examine the effect of heat treatment on polycrystalline Ti50.9 at.%Ni subsequent to hot-rolling. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation processed NiTi. The results constitute a fundamental understanding of the effect of heat treatment on thermal/stress induced martensite, which is critical for optimizing mechanical properties. The high temperature of the hot-rolling process caused recrystallization, recovery, and hindered precipitate formation, essentially solutionizing the NiTi. Subsequent heat treatments were carried out at various temperatures for 1.5 hours. Transmission Electron Microscopy (TEM) observations revealed that Ti3NI4 precipitates progressively increased in size and changed their interface with the matrix from being coherent to incoherent with increasing heat treatment temperature. Accompanying the changes in precipitate size and interface coherency, transformation temperatures were observed to systematically shift, leading to the occurrence of the R-phase and multiple-stage transformations. Room temperature stress-strain tests illustrated a variety of mechanical responses for the various heat treatments, from pseudoelasticity to shape memory. The changes in stress-strain behavior are interpreted in terms of shifts in the primary martensite transformation temperatures, rather then the occurrence of the R-phase transformation. The results confirm that Ti 3Ni4 precipitates can be used to elicit a desired isothermal stress-strain behavior in polycrystalline NiTi.
UR - http://www.scopus.com/inward/record.url?scp=34249872428&partnerID=8YFLogxK
U2 - 10.1557/proc-855-w1.9
DO - 10.1557/proc-855-w1.9
M3 - Conference contribution
AN - SCOPUS:34249872428
SN - 1558998071
SN - 9781558998070
T3 - Materials Research Society Symposium Proceedings
SP - 19
EP - 24
BT - Mechanically Active Materials
PB - Materials Research Society
T2 - 2004 MRS Fall Meeting
Y2 - 29 November 2004 through 3 December 2004
ER -