| 1. |
- Hedström, Peter, et al.
(författare)
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Load partitioning and strain-induced martensite formation during tensile loading of a metastable austenitic stainless steel
- 2009
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 40:5, s. 1039-1048
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Tidskriftsartikel (refereegranskat)abstract
- In-situ high-energy X-ray diffraction and material modeling are used to investigate the strain-rate dependence of the strain-induced martensitic transformation and the stress partitioning between austenite and α′ martensite in a metastable austenitic stainless steel during tensile loading. Moderate changes of the strain rate alter the strain-induced martensitic transformation, with a significantly lower α′ martensite fraction observed at fracture for a strain rate of 10−2 s−1, as compared to 10−3 s−1. This strain-rate sensitivity is attributed to the adiabatic heating of the samples and is found to be well predicted by the combination of an extended Olson–Cohen strain-induced martensite model and finite-element simulations for the evolving temperature distribution in the samples. In addition, the strain-rate sensitivity affects the deformation behavior of the steel. The α′ martensite transformation at high strains provides local strengthening and extends the time to neck formation. This reinforcement is witnessed by a load transfer from austenite to α′ martensite during loading.
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| 2. |
- Oden, Magnus, et al.
(författare)
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In situ small-angle x-ray scattering study of nanostructure evolution during decomposition of arc evaporated TiAlN coatings
- 2009
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Ingår i: APPLIED PHYSICS LETTERS. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:5, s. 053114-
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Tidskriftsartikel (refereegranskat)abstract
- Small-angle x-ray scattering was used to study in situ decomposition of an arc evaporated TiAlN coating into cubic-TiN and cubic-AlN particles at elevated temperature. At the early stages of decomposition particles with ellipsoidal shape form, which grow and change shape to spherical particles at higher temperatures. The spherical particles grow at a rate of 0.18 A/degrees C while coalescing.
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| 3. |
- Terner, Mark, et al.
(författare)
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Residual stress evolution during decomposition of Ti(1-x)Al (x)N coatings using high-energy x-rays
- 2006
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Ingår i: RESIDUAL STRESSES VII. - : Transtec Publications; 1999. ; 524-525, s. 619-624, s. 619-624
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Konferensbidrag (refereegranskat)abstract
- Residual stresses and microstructural changes during phase separation in Ti33Al67N coatings were examined using microfocused high energy x-rays from a synchrotron source. The transmission geometry allowed simultaneous acquisition of x-ray diffraction data over 360 degrees and revealed that the decomposition at elevated temperatures occurred anisotropically, initiating preferentially along the film plane. The as-deposited compressive residual stress in the film plane first relaxed with annealing, before dramatically increasing concurrently with the initial stage of phase separation where metastable, nm-scale c-AlN platelets precipitated along the film direction. These findings were further supported from SAXS analyses.
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