| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Tabiri, S, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 5. |
- Bravo, L, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 6. |
|
|
| 7. |
- Bhattacharjee, T., et al.
(författare)
-
Effect of low temperature on tensile properties of AlCoCrFeNi2.1 eutectic high entropy alloy
- 2018
-
Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584. ; 210, s. 207-212
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of low temperature on tensile properties of a AlCoCrFeNi 2.1 eutectic high entropy alloy (EHEA) was investigated in the present work. Transmission electron microscopy (TEM) showed that the initial as-cast microstructure consisted of B2 (ordered body centered cubic structure) and L1 2 (ordered face centered cubic structure) phases. Upon tensile testing at temperatures ranging from room temperature (RT) to −196 °C (77 K), the L1 2 phase became disordered, changing to a simple FCC (face centered cubic) crystal structure whereas the B2 phase maintained an ordered structure. An increase over 300 MPa was observed in the ultimate tensile strength (σ UTS ) of the −196 °C tensile tested sample compared to the room temperature tensile tested sample, while keeping almost similar amount of total elongation. TEM results indicated an increase in the dislocation activity in the FCC phase as well as B2 phase in the −196 °C tensile tested sample compared to the sample deformed at room temperature.
|
|
| 8. |
- Bhattacharjee, T., et al.
(författare)
-
Simultaneous Strength-Ductility Enhancement of a Nano-Lamellar AlCoCrFeNi2.1 Eutectic High Entropy Alloy by Cryo-Rolling and Annealing
- 2018
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- Nano-lamellar (L1 2 + B2) AlCoCrFeNi 2.1 eutectic high entropy alloy (EHEA) was processed by cryo-rolling and annealing. The EHEA developed a novel hierarchical microstructure featured by fine lamellar regions consisting of FCC lamellae filled with ultrafine FCC grains (average size ∼200-250 nm) and B2 lamellae, and coarse non-lamellar regions consisting of ultrafine FCC (average size ∼200-250 nm), few coarse recrystallized FCC grains and rather coarse unrecrystallized B2 phase (∼2.5 μm). This complex and hierarchical microstructure originated from differences in strain-partitioning amongst the constituent phases, affecting the driving force for recrystallization. The hierarchical microstructure of the cryo-rolled and annealed material resulted in simultaneous enhancement in strength (Yield Strength/YS: 1437 ± 26 MPa, Ultimate Tensile Strength/UTS: 1562 ± 33 MPa) and ductility (elongation to failure/e f ∼ 14 ± 1%) as compared to the as-cast as well as cold-rolled and annealed materials. The present study for the first time demonstrated that cryo-deformation and annealing could be a novel microstructural design strategy for overcoming strength-ductility trade off in multiphase high entropy alloys.
|
|
| 9. |
- Wani, I. S., et al.
(författare)
-
Cold-rolling and recrystallization textures of a nano-lamellar AlCoCrFeNi2.1 eutectic high entropy alloy
- 2017
-
Ingår i: Intermetallics. - : Elsevier BV. - 0966-9795. ; 84, s. 42-51
-
Tidskriftsartikel (refereegranskat)abstract
- The development of texture during cold-rolling and recrystallization was investigated in a AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA). For this purpose, the as-cast alloy was cold-rolled to 90% reduction in thickness and annealed at temperatures ranging from 800 °C to 1200 °C. The microstructure of the as-cast EHEA showed a nano-lamellar mixture of L12 and B2 phases. The B2 phase was significantly harder than the L12 phase. Development of an ultrafine microstructure was observed after 90% cold-rolling. During cold-rolling, progressive disordering of the L12 phase was observed while the B2 phase maintained the ordered structure. The progressive disordering and development of a predominantly brass type texture in the L12 phase correlated well with profuse shear band formation during cold-rolling. The B2 phase showed the presence of the {111} component which was typical for cold-rolled B2 alloys. An ultrafine duplex structure of equiaxed L12 and B2 phases developed after complete recrystallization that showed significant resistance to grain growth up to very high annealing temperatures (?1300 °C). The remarkable resistance to grain growth compared to conventional or even other single or dual phase HEAs was due to the formation of a homogeneous duplex structure where growth of one phase was effectively retarded by the other phase. The strong presence of the ?-fiber components, but weak BR ({236} ) and D ({113} ) components in the recrystallization texture of the L12/FCC phase was due to the absence of strong preferential nucleation or growth. Presence of ND-fiber (ND// ) with strong {111} component in the recrystallization texture of the B2 phase indicated ease of nucleation from similarly oriented regions in the deformed microstructure.
|
|
| 10. |
- Patel, A., et al.
(författare)
-
Strain-path controlled microstructure, texture and hardness evolution in cryo-deformed AlCoCrFeNi2.1 eutectic high entropy alloy
- 2018
-
Ingår i: Intermetallics. - : Elsevier BV. - 0966-9795. ; 97, s. 12-21
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of strain path on microstructure, texture and hardness properties of AlCoCrFeNi 2.1 eutectic high entropy alloy containing ordered FCC (L1 2 ) and ordered BCC (B2) was investigated. The EHEA was cryo-rolled using UCR, MSCR (during which the samples were rotated by 90° around the ND between each pass) and TSCR(45°) (in which the samples were deformed by unidirectional rolling to half of the total strain and then diagonally rolled for rest half of the strain). The UCR processed material showed a rather heterogeneous microstructure. The textures of the L1 2 /FCC and B2 phases in the MSCR processed material agreed with the cross-rolling texture of the corresponding single phase materials, while the texture of the two phases in the TSCR(45°) processed materials appeared rather weak. Upon annealing at 800 °C, the UCR processed materials showed a novel heterogeneous microstructure, while the MSCR and TSCR(45°) processed materials revealed microduplex structure. The heterogeneous microstructure was replaced by the usual microduplex structure at higher annealing temperatures. The annealing texture of the L1 2 /FCC phase showed the presence of α-fiber (ND// < 011 > ) components while the B2 phase showed strong ND-fiber (ND// < 111 > ) components. The UCR processed material with novel heterogeneous microstructure showed much greater hardness as compared to the MSCR and TSCR(45°) processed materials. The present results indicate that strain path exerted significant influence in controlling microstructure, texture and hardness properties of EHEA.
|
|
| 11. |
- Wani, I. S., et al.
(författare)
-
Effect of severe cold-rolling and annealing on microstructure and mechanical properties of AlCoCrFeNi 2.1 eutectic high entropy alloy
- 2017
-
Ingår i: IOP Conference Series: Materials Science and Engineering. - 1757-8981 .- 1757-899X. ; 194:1
-
Konferensbidrag (refereegranskat)abstract
- The possibility of microstructural refinement and improvement of mechanical properties by severe cold-rolling was investigated in an AlCoCrFeNi2.1 lamellar eutectic high entropy alloy (EHEA). The as-cast alloy revealed fine scale eutectic mixture of L12 (ordered FCC) and B2 (ordered BCC) phases. During severe cold-rolling up to 90% reduction in thickness the B2 phase maintained the ordered structure, while the L12 phase showed the evolution of a nanocrystalline structure and progressive disordering. Annealing of the severely cold-rolled material resulted in the formation of duplex microstructures composed of two different phases with equiaxed morphologies and significant resistance to grain growth up to 1200°C. Annealing at 1000°C resulted in an optimum strength-ductility balance with the tensile strength of 1175 MPa and the total elongation of 23%. The present results showed that severe cold-rolling and annealing can impart very attractive mechanical properties in complex EHEAs.
|
|
| 12. |
- Wani, I. S., et al.
(författare)
-
Tailoring nanostructures and mechanical properties of AlCoCrFeNi2.1 eutectic high entropy alloy using thermo-mechanical processing
- 2016
-
Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 675, s. 99-109
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of thermo-mechanical processing on the evolution of microstructure and mechanical properties was investigated in an AlCoCrFeNi2.1 high entropy alloy. For this purpose, the alloy was cold-rolled to 90% reduction in thickness and annealed at temperatures ranging from 800 °C to 1200 °C. The as-cast alloy revealed eutectic lamellar mixture of (Ni, Al) rich but Cr depleted B2 phase and Al-depleted L12 phases, having volume fractions of ~35% and 65%, respectively. Nanosized precipitates enriched in Cr and having disordered BCC structure were found dispersed inside the B2 phase. Cold-rolling resulted in progressive disordering of the L12 phase but the B2 phase maintained the ordered structure. The disordering of the L12 phase was accompanied by the evolution of ultrafine lamellar structure and profuse shear band formation. Annealing of the 90% cold-rolled material at 800 °C resulted in the formation of a duplex microstructure composed of two different phases with equiaxed morphologies, having significant resistance to grain growth up to 1200 °C. The annealed materials showed disordered FCC and precipitate-free B2 phases. This indicated that quenching of the annealed specimens to room temperature was sufficient to prevent the ordering of the L12 phase and the formation of the Cr-rich nano-precipitates which were dissolved in the B2 phase during annealing. Significant improvement in tensile properties compared to the as-cast alloy could be achieved by thermo-mechanical processing. All the specimens annealed at 800 °C to 1200 °C were having good tensile ductility over 10% as well as high tensile strength greater than 1000 MPa. These indicated that the properties of the EHEA could be successfully tailored using thermo-mechanical processing for a wide range of engineering applications.
|
|
| 13. |
- Wani, I. S., et al.
(författare)
-
Ultrafine-Grained AlCoCrFeNi2.1 Eutectic High-Entropy Alloy
- 2016
-
Ingår i: Materials Research Letters. - : Informa UK Limited. - 2166-3831. ; 4:3, s. 174-179
-
Tidskriftsartikel (refereegranskat)abstract
- The development of microstructure and mechanical properties was investigated in a heavily cold-rolled and annealed AlCoCrFeNi2.1 high-entropy alloy. The as-cast alloy having a eutectic morphology consisting of alternate bands of ordered L1(2) and B2 phases was 90% cold-rolled. The deformed microstructure showed profuse shear banding and disordering of the L12, but no transformation of the B2 phase. A duplex microstructure consisting of ultrafine equiaxed grains (similar to 0.60 mu m) of disordered face centered cubic and B2 was observed after annealing at 800 degrees C. The annealed material showed remarkable strength-ductility combination having ultimate tensile strength similar to 1.2 GPa and elongation to failure similar to 12%.
|
|
