Microstress evolution during in situ loading of a superalloy containing high volume fraction of γ′ phase

Ma, Shouxiang; Rangaswamy, P.; Majumdar, B.S.

doi:10.1016/s1359-6462(02)00504-3

Cited by 38 publications

(22 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The TEM micrograph in Figure 8 also confirms dislocation entry into γ'. Similar bendback was also noted for a tensile tested polycrystalline CM247LC sample at RT [11].…”

Section: Tension Test Of Ds Alloy At 900 Csupporting

confidence: 78%

“…For the corresponding (200) reflection, that includes intensity from both the  γ' and  γ phases, d 200 of  γ' was equated to d 100 /2. The intensity ratio of γ' to γ was determined from the structure factor and volume fraction, using equation below [11]: …”

Section: Methodsmentioning

confidence: 99%

“…Tests were conducted on a [001] oriented PWA1422 DS alloy (no Re) at 900°C, and on a PWA 1484 SX alloy (3 wt.% Re) at 1092 C. The tests were accompanied with micromechanical modeling and TEM observation of dislocation structures, although some of these details will not be presented in this paper. Publications related to this work may be obtained from [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Elastic Microstrains during Tension and Creep of Superalloys: Results from In Situ Neutron Diffraction

Lu¹,

Ma²,

Majumdar³

2008

Superalloys 2008 (Eleventh International Symposium)

Self Cite

View full text Add to dashboard Cite

In situ neutron diffraction experiments were conducted to monitor elastic microstrains during tension and creep of a directionally solidified (DS) superalloy PWA1422 and a single crystal (SX) alloy PWA 1484. The rationale was to obtain insight on internal stress evolution, and thereby improved understanding of deformation mechanisms. The misfit between the gamma (γ) and gamma-prime (γ') phases were determined as a function of temperature and deformation. The microstrains in the tension test were used to obtain the critical resolved shear stress (CRSS) of the phases. Results show a dramatic increase in the CRSS of the γ-phase compared to the bulk, and are consistent with dislocations bowing (Orowan type) between narrow γ-channels. A threshold stress is calculated for dislocation activity in the horizontal channel, and is suggested as a minimum stress for initiating any creep or rafting. Microstrains from the creep test at 900°C/425 MPa are consistent with the formation of dislocation networks, but the data do not suggest that the CRSS is exceeded for cutting of the γ'. Rather, rafting is suggested for the onset of tertiary creep. At 1092°C/120 MPa, the far-field creep strain exhibits an unusual behavior in the pre-steady-state low strain (<0.5%) regime. This is also accompanied with creep acceleration and decrease of elastic strain in γ'. The response is accompanied with the formation of a completely rafted microstructure. An explanation is provided in terms of deposition of actual misfit dislocations preferentially on the vertical interfaces.

show abstract

“…The TEM micrograph in Figure 8 also confirms dislocation entry into γ'. Similar bendback was also noted for a tensile tested polycrystalline CM247LC sample at RT [11].…”

Section: Tension Test Of Ds Alloy At 900 Csupporting

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Elastic Microstrains during Tension and Creep of Superalloys: Results from In Situ Neutron Diffraction

Lu¹,

Ma²,

Majumdar³

2008

Superalloys 2008 (Eleventh International Symposium)

Self Cite

View full text Add to dashboard Cite

show abstract

“…These are seen as beneficial effects particularly with reference to the eventual high temperature mechanical properties of the material. On the other hand, rapid cooling may encourage high residual stresses across the width of the weld Ma et al, 2003), promoting hot tearing during solidification (Thompson and Genculu, 1983) or post-solidification cracking (Dye, 2000). The control of heat flux is considered a key parameter, influencing internal stresses and component distortion and affecting the consistency of welding.…”

Section: Straight Line Single Stringer/multiple Layer Depositionsmentioning

confidence: 99%

Shaped metal deposition of a nickel alloy for aero engine applications

Clark

Bache

Whittaker

2008

Journal of Materials Processing Technology

197

View full text Add to dashboard Cite

“…[21] The reflection profiles were fitted using a Voigt function, and the profiles of the c and c¢ phases were separated from the measured raw profile by using the volume fractions of the phases as the constraint conditions in the refinement. [18,22] …”

Section: Internal Stress Calculationsmentioning

confidence: 99%

Neutron and X-Ray Diffraction Study of Internal Stress in Thermomechanically Fatigued Single-Crystal Superalloy

Wu¹,

Jin-Chao²,

Zhang³

et al. 2008

Metall Mater Trans A

View full text Add to dashboard Cite

The relationship between internal stress and thermomechanical fatigue (TMF) in a Ni-based single-crystal superalloy is studied by neutron and X-ray diffraction. The extents of internal stress, deformation, lattice mismatch, and distortion during TMF are characterized by the determined deviatoric stress invariants and lattice parameters and compared with relevant microstructural information from scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that, in general, the macroscopic stress, plastic deformation, lattice mismatch, and distortion have all increased during TMF. The lattice mismatches of the TMF samples are at a high level, where the values along [100]/[010] are negative, but those along [001] are positive. The tetragonal lattice distortion of the c matrix is slightly greater than that of the c¢ precipitates, where the c/a values of the c matrix are smaller than 1, but that of the c¢ precipitate larger than 1. The c matrix yields and becomes hardened at the initial TMF cycle and gradually loses most of its strength during the earlier TMF cycles, associated with stress relaxation and homogenous deformation. However, the c¢ precipitates yield and become hardened later, bearing the most stress up to the necking of the superalloy. This process is associated with a buildup of stress and significant concentrated and inhomogeneous distribution of deformation in the c¢ precipitate. The residual deformation states of the superalloy and its component phases at the earlier TMF are basically shearing, and only become stretched at a later stage of TMF. The microstructure of the TMF samples shows an initial stage of rafting, where the dislocations are accumulated at the c=c 0 interfaces of the c matrix channels, but both dislocation networks and stacking faults are inhomogeneously distributed in the c¢ precipitates.

show abstract

Microstress evolution during in situ loading of a superalloy containing high volume fraction of γ′ phase

Cited by 38 publications

References 4 publications

Elastic Microstrains during Tension and Creep of Superalloys: Results from In Situ Neutron Diffraction

Elastic Microstrains during Tension and Creep of Superalloys: Results from In Situ Neutron Diffraction

Shaped metal deposition of a nickel alloy for aero engine applications

Neutron and X-Ray Diffraction Study of Internal Stress in Thermomechanically Fatigued Single-Crystal Superalloy

Contact Info

Product

Resources

About