| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Moverare, Johan, et al.
(author)
-
Thermomechanical Fatigue of Single-Crystal Superalloys : Influence of Composition and Microstructure
- 2012
-
In: Superalloys 2012. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9780470943205 - 9781118516430 ; , s. 369-377
-
Conference paper (peer-reviewed)abstract
- The thermomechanical fatigue (TMF) behaviour of a new high Cr-containing single crystal superalloy, known as STAL-15, is investigated. This is a candidate alloy for future industrial gas turbine (IGT) applications. TMF involves complex interactions between high and low temperature deformation mechanism, and this study highlights important factors controlling their interrelationship. Emphasis is placed particularly on the microslructural aspects which control deformation. It is demonstrated that the TMF performance of the new alloy is comparable to that of a second generation alloy such as CMSX-4, despite the absence of Re alloying. An addition of 0.25wt% Si significantly improves the resistance to TMF further; this is attributed to a greater resistance to recrystallization and cracking along the deformation bands that develops across the cross section of the specimen during testing. The TMF resistance increases with increasing primary γ′ size, but the degree of solutioning of the γ′ phase caused by the solution heat treatment seems to have no significant effect.
|
|
| 7. |
- Sadrossadat, Mohsen, 1963-, et al.
(author)
-
EBSD investigation of the effect of the solidification rate on the nucleation behavior of eutectic components in a hypoeutectic Al-Si-Cu alloy
- 2012
-
In: Metals and Materials International. - : Springer Science and Business Media LLC. - 1598-9623 .- 2005-4149. ; 18:3, s. 405-411
-
Journal article (peer-reviewed)abstract
- This article is devoted to a study of the influence of solidification rate on the crystallographic orientation of eutectic components with respect to primary α-Al in the tested hypoeutectic alloy. Electron backscattering diffraction (EBSD) patterns were produced from Al-Si cast specimens, solidified with different cooling rates, and prepared by ion etch polishing as a complementary method after mechanical polishing. Results indicated a strong orientation relationship between the primary α-Al and eutectic aluminum phase at all cooling rates. It is also found that the silicon eutectic flakes are nucleated heterogeneously in the interdendritic eutectic liquid. Increasing the cooling rate from 2 to 80 mm/min is observed to be effective in lowering the intensity of relationship between the primary α-Al and eutectic aluminum phase and changing the misorientation angle clustering between primary α-Al and eutectic silicon phase in the interval 41-60 to lower angle intervals.
|
|
| 8. |
- Segersäll, Mikael, et al.
(author)
-
Deformation and Damage Mechanisms During Thermomechanical Fatigue of a Single-crystal Superalloy in the <001> and <011> Directions
- 2012
-
In: Superalloy 2012. - : The Minerals, Metals, and Materials Society. - 9780470943205 ; , s. 215-223
-
Conference paper (peer-reviewed)abstract
- The purpose of this paper is to investigate the differences in mechanical response and microstructural behavior when the single-crystal Ni-based superalloy CMSX-4 is subjected to thermomechanical fatigue (TMF) in two different crystallographic directions, <001> and <011>. An out-of-phase (OP) straincontrolled TMF cycle with R=-∞ in the temperature range 100 to 850 °C was used. As expected, the material exhibited, when loaded in the <001> direction, a higher number of cycles to failure compared to the <011> direction, when equivalent strain ranges were compared. High strain ranges led to crystallographic fractures along one of the {111} planes while low strain ranges led to non-crystallographic fractures. This result was valid for both <001> and <011> directions. Specimens with random fractures also showed recrystallization close to the fracture surface. Twinning was found to be a major deformation mechanism for most specimens. A change in deformation mechanism from twinning to shearing was found in specimens subjected to loading in the <011> direction when going from low to high strain ranges. This investigation also indicated that crack propagation is a consequence of recrystallization and not the other way around.
|
|
| 9. |
- Xi, Wenjun, et al.
(author)
-
Al2O2 Nanoparticle Reinforced Fe-based Alloys Synthesized by Thermite Reaction
- 2012
-
In: Journal of Materials Science. - : Springer Berlin/Heidelberg. - 0022-2461 .- 1573-4803. ; 47:8, s. 3585-3591
-
Journal article (peer-reviewed)abstract
- It is very difficult to manufacture oxide nanoparticle strengthened alloys through the conventional casting in the gravity field or even in the space microgravity environment. A thermite reaction process was used to produce molten metal that was then solidified in a graphite mold in super gravity field caused by centrifugal force; we were able to obtain Al2O3 nanoparticle reinforced Fe-based alloys. The formation of Al2O3 nanoparticles was related to the addition of TiO2 xerogel to the thermite mixture, and their uniform distribution in the alloy can be explained by their assembly in (Ni, Fe)Al intermetallics during solidification owing to the low interfacial energy between them.
|
|
| 10. |
- Yuan, Kang, et al.
(author)
-
Analysis on Microstructural Evolution of PtAl Diffusion Coating on Ni-based Superalloy Influenced by Creep Process
- 2012
-
Conference paper (other academic/artistic)abstract
- The microstructural evolution of PtAl diffusion coating on a nickel-base superalloy IN792 was studied to assess the influence of high temperature (850 °C and 950 °C) and static creep loading conditions. The chemical composition analysis by EDS reveals that local enrichment of Cr, W and Mo is responsible for the formation of σ, Cr-α and μ/R particles in the different characteristic zones in the PtAl coating. Being taken as an approach to describe the coating’s microstructure evolution, a so-called Effective Coating Thickness (ECT) is defined and was measured for different creep conditions. It is found that the value of ECT is controlled by the inward diffusion of Al and Pt, being demonstrated by the existence of a linear correlation between ECT and diffusion coefficient of Al in substrate; t: diffusion time). Simulated ECT development of the PtAl diffusion coating agrees well with the experimental results at 850 °C and 950 °C.
|
|
