Effect of Heat Treatment on Microstructure and Mechanical Property of 45XD and 47XD TiAl Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 581-584 ◽  
Author(s):  
H. Zhu ◽  
Dong Yi Seo ◽  
Kouichi Maruyama
Keyword(s):  
Heat Treatment ◽  
Mechanical Property ◽  
Lamellar Structure ◽  
Tial Alloys ◽  
Fine Grained ◽  
Break Up ◽  
Fully Lamellar ◽  
Hardness Values ◽  
Microstructure And Mechanical Property ◽  
Microstructural Examination

The effect of heat treatment on microstructure and property of Ti-45 and 47Al-2Nb-2Mn+0.8%vol.%TiB2 alloys (45XD and 47XD) has been studied. Annealing and subsequent oil quench produced fine-grained fully lamellar structure (FGFL) in both alloys. For microstructural stabilization, the FGFL structures were subjected to different aging treatments. Microstructural examination showed that degradation of the FGFL structure, such as coarsening of γ lamellae, recrystallization of γ grains and break-up of a2 lamellae, presented to varying degrees after different aging treatments. Hardness values in the aged alloys decreased due to the degradation. The creep resistances were improved in the aged alloys though the degradation occurred, indicating that the aging treatments stabilized the FGFL structures effectively. The differences in the changes of properties caused by different aging treatments and compositions were compared in combination with the microstructural variants.

Influence of Step Aging on Creep Behavior and Microstructural Evolution of Fine-Grained Fully Lamellar XD TiAl Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1525-1530
Author(s):  
Han Liang Zhu ◽  
Dong Yi Seo ◽  
Kouichi Maruyama ◽  
Peter Au
Keyword(s):  
Creep Rate ◽  
Microstructural Evolution ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Lamellar Structure ◽  
Aging Condition ◽  
Tial Alloys ◽  
Fine Grained ◽  
Fully Lamellar ◽  
Multiple Step

Fine-grained fully lamellar (FGFL) structures of XD TiAl alloys (Ti-45 and 47Al-2Nb-2Mn+0.8vol.%TiB2) (at.%) were stabilized to varying degrees by different aging treatments. Specimens with and without aging were creep tested at 760°C and 207 MPa. It was found that during creep deformation, degradation of the lamellar structure involving coarsening within the colonies and spheroidization at colony boundaries occurred, forming fine globular structures at the colony boundaries and increasing the creep rate. Aging treatments stabilized the lamellar structure and retarded the coarsening and spheroidization processes during creep deformation. As a result, the aged specimens exhibited lower minimum creep rates and longer creep lives than the unaged specimens. A multiple step aging stabilized the lamellar structure to the greatest extent and suppressed other degradation processes during aging, resulting in the best creep resistance. These results demonstrate that the multiple step aging is the optimal aging condition for stabilizing FGFL XD TiAl alloys.

Ductile TiAl alloy with a Widmanstätten lamellar structure formed by rapid heating

2008 ◽  
Vol 23 (4) ◽  
pp. 949-953 ◽  
Author(s):  
J.P. Cui ◽  
M.L. Sui ◽  
Y.Y. Cui ◽  
D.X. Li
Keyword(s):  
Electric Current ◽  
Lamellar Structure ◽  
Tial Alloy ◽  
Rapid Heating ◽  
Pulse Treatment ◽  
Electric Current Pulse ◽  
Microstructural Refinement ◽  
Tial Alloys ◽  
Refinement Mechanism ◽  
Fully Lamellar

Instead of conventional grain-refinement treatments for improving the ductility of fully lamellar TiAl alloys, multiorientational, lamellar, subcolony refinement with good ductility has been achieved simply by using an electric-current pulse treatment. The microstructural refinement mechanism is attributed to the transformation on heating of γ laths in the prior large-grain lamellar structure to Widmanstätten α in several orientations, which on subsequent cooling forms lamellar structure colonies in multiple orientations. This kind of refined multiple-colony lamellar structure was found to enhance the ductility of the TiAl alloy.

Effects of Modification and Heat Treatment on Microstructure and Mechanical Property of Two-Step Foamed ZL111 Alloy Foam

2018 ◽  
Vol 933 ◽  
pp. 68-77
Author(s):  
Yu Yuan Jiang ◽  
Xiao Xu Luo ◽  
Qing Chen ◽  
Ming Wei Zhao ◽  
Jian Sheng Lu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Mechanical Property ◽  
Eutectic Silicon ◽  
Absorption Capacity ◽  
Compressive Property ◽  
Average Pore ◽  
T6 Heat Treatment ◽  
Sr Modification ◽  
Average Size ◽  
Microstructure And Mechanical Property

ZL111 alloy foams with a porosity of 80% and an average pore diameter of 3.5 mm were fabricated using a two-step foaming process, and the effects of modification and heat treatment on their microstructure and mechanical property were studied. The results indicates that by Y&Sr modification, most of the eutectic silicon in the ZL111 alloy foam is transformed from plate-like into dot-like forms, and the average size of evenly distributed α-Al grain is reduced from 80~100μm to 30~40μm, which is more efficient than separate Y or Sr modifications. By combining Y and Sr modification and T6 heat treatment, the α-Al grain size of ZL111 alloy foam maintains its previous modified effect, eutectic silicon remains spherical and well-distributed, and CuAl2and Al9FeMg3Si5are dispersed homogeneously at the α-Al grain boundary. The Y&Sr modification and T6 heat treatment also significantly improved the compressive property of ZL111 alloy foam, when we compared them with the untreated ZL111 alloy foam. The compressive strength rises from 13.3 MPa to 22.6 MPa, the densification strain improves from 59.3% to 76.9%, and the energy absorption capacity increases from 4.87 MJ/m3to 13.77 MJ/m3.

scholarly journals Effect of Post Processing Heat Treatment Routes on Microstructure and Mechanical Property Evolution of Haynes 282 Ni-Based Superalloy Fabricated with Selective Laser Melting (SLM)

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 629
Author(s):  
Anagh Deshpande ◽  
Subrata Deb Nath ◽  
Sundar Atre ◽  
Keng Hsu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Property ◽  
High Temperature ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Step Heat Treatment ◽  
Microstructure And Mechanical Property ◽  
In Situ Heat Treatment

Selective laser melting (SLM) is one of the most widely used additive manufacturing technologies. Fabricating nickel-based superalloys with SLM has garnered significant interest from the industry and the research community alike due to the excellent high temperature properties and thermal stability exhibited by the alloys. Haynes-282 alloy, a γ′-phase strengthened Ni-based superalloy, has shown good high temperature mechanical properties comparable to alloys like R-41, Waspaloy, and 263 alloy but with better fabricability. A study and comparison of the effect of different heat-treatment routes on microstructure and mechanical property evolution of Haynes-282 fabricated with SLM is lacking in the literature. Hence, in this manuscript, a thorough investigation of microstructure and mechanical properties after a three-step heat treatment and hot isostatic pressing (HIP) has been conducted. In-situ heat-treatment experiments were conducted in a transmission electron microscopy (TEM) to study γ′ precipitate evolution. γ′ precipitation was found to start at 950 °C during in-situ heat-treatment. Insights from the in-situ heat-treatment were used to decide the aging heat-treatment for the alloy. The three-step heat-treatment was found to increase yield strength (YS) and ultimate tensile strength (UTS). HIP process enabled γ′ precipitation and recrystallization of grains of the as-printed samples in one single step.

Investigation of Microstructure and Property of the Fe3Al/Al2O3 Composites Fabricated by Mechanical Alloying Process and Plasma Active Sintering Process

2011 ◽  
Vol 194-196 ◽  
pp. 1689-1692
Author(s):  
Tao Jiang
Keyword(s):  
Heat Treatment ◽  
Mechanical Property ◽  
Phase Composition ◽  
Mechanical Alloying ◽  
Sintering Process ◽  
Composite Powders ◽  
Al Content ◽  
The Mean ◽  
Xrd Patterns ◽  
Microstructure And Mechanical Property

The Fe3Al/Al2O3composites were fabricated by plasma active sintering process. The Fe3Al intermetallics compounds powders were fabricated by mechanical alloying and heat treatment, then the Fe3Al powders and Al2O3powders were mixed and the Fe3Al/Al2O3composite powders were prepared, so the Fe3Al/Al2O3composites were fabricated by plasma active sintering process at 1200°C for 5min under the pressure of 30MPa. The phase composition and microstructure of the Fe3Al intermetallics compounds powders produced by mechanical alloying and heat treatment were investigated. The phase composition, microstructure and mechanical property of the Fe3Al/Al2O3composites sintered bulks were investigated. The XRD patterns results showed that there existed Fe3Al phase and Al2O3phase in the sintered composites. The Fe3Al/Al2O3composites sintered bulks exhibited the homogenous and compact microstructure, the Fe3Al particles were homogenously distributed in the Al2O3matrix. The mean particles size of Fe3Al intermetallics was about 2-3μm and mean particles sizes of Al2O3was about 2-3μm. The density and relative density of the Fe3Al/Al2O3composites increased gradually with the increase of Fe3Al content. The fracture strength and fracture toughness of the Fe3Al/Al2O3composites increased gradually with the increase of Fe3Al content. The elastic modulus and hardness(HRA) of Fe3Al/Al2O3composites decreased gradually with the increase of Fe3Al content.

Beneficial Effects of Boron Addition into γ-TiAl Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1451-1456 ◽  
Author(s):  
Z.X. Li ◽  
Xia Huang ◽  
L.C. Qi ◽  
Chun Xiao Cao
Keyword(s):  
Lamellar Structure ◽  
Tial Alloy ◽  
Eutectic Reaction ◽  
Rupture Life ◽  
Boron Addition ◽  
Tial Alloys ◽  
Beneficial Effects ◽  
Rich Alloy ◽  
Fully Lamellar ◽  
Thermal Stability Of

The beneficial effects of boron addition on microstructure transformations and mechanical properties of γ-TiAl alloys were investigated. Two growth mechanisms of boride (TiB2) in γ-TiAl alloy were confirmed, the curved flaky borides are products of irregular eutectic reaction growing coupled with matrix, while some faceted blocky borides in boron-rich alloy are primary TiB2 phase growing directly in melt. The core of flaky TiB2 is ultra-fine B2 phase and there has an orientation relationship [1210] TiB2//[001]B2, (1010) //(010)B2. In addition to the well-known grain refinement effect, boron addition can suppress the formation of metastable feathery and Widmastätten structure and broadens cooling-rate-range for the formation of fully lamellar structure, consequently, it improves thermal stability of the lamellar structure and accordingly prolongs the creep rupture life significantly. Another beneficial effect of boron addition is that boride can restrain discontinuous coarsening on lamellar grain boundary by pinning action and accelerates recrystallization of γ grain by introducing TiB2/matrix interfaces as nuclear sites during homogeneous treatment at 1150°C. Therefore, compared with boron-free alloy more homogeneous and refined near γ microstructure can be obtained in boron modified alloy.

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