Internal Mismatch Stresses in Nickel-Based Superalloys : A Finite Element Approach

Hazotte, Alain; Racine, A.; Denis, S.

doi:10.1051/jp4:1996112

“…The amorphous nature of the nitride precipitates makes it impossible for this morphology to be of crystallographic origin. It is rather thought that it is due to the matrix elastic anisotropy and that this particular shape minimizes the elastic strain energy related to precipitation, as similar morphologies have already been explained with this parameter in different systems,17 especially when the precipitate is stiffer than the matrix,18 exactly the situation described in this paper.…”

Section: Resultssupporting

confidence: 69%

Investigation of a Ferrite/Silicon Nitride Composite Concept Aimed at Automotive Applications

Landeghem

¹

,

Gouné

²

,

Redjaïmia

³

2012

steel research int.

View full text Add to dashboard Cite

This paper presents the investigation of the behavior of a Fe–1.5 wt% Si thin sheet upon plasma‐assisted nitriding at 570°C. It had been confirmed that a very fine and intense precipitation of amorphous silicon nitride occurs as nitrogen diffuses into the sheet. The precipitates, the size of which is comprised between several and several tens of nanometer, display a cubic morphology in spite of their amorphous structure. These cubes adopt a particular morphology in relation to the matrix with their faces parallel to the {100} plane family. These precipitates cause a notable hardening of the alloy and it was possible to harden a 1 mm sheet across its whole thickness in under 8 h.

show abstract

“…( 2 –5) 64 – 69 : where M = 3.06 for FCC structure (Taylor factor) 68 , α ε = 2.6 (a constant) 66 , 67 , m = 0.85 (a constant) 70 , 71 , δ c = 2 δ /3 66 , 67 , the constrained lattice misfit. G = 81 GPa and ΔG = 4 GPa are the shear modulus of the matrix and the shear modulus misfit between precipitates and matrix, respectively 72 ; b = 0.254 nm is the Burgers vector 6 , 72 ; r is the average particle size (i.e., the average edge length of cuboidal precipitates measured from experimental observations) and f is the volume fraction of the γ′ precipitates, respectively; γ APB = 0.12 J/m 2 is the anti-phase boundary energy of γ′-Ni 3 Al 72 ; ν is the Poisson ratio ( ν = 0.35 for Ni-base superalloys 73 ), and λ p is the inter-precipitate space.…”

Section: Correlations Among Lattice Misfit Particle Morphology and mentioning

confidence: 99%

Composition rules of Ni-base single crystal superalloys and its influence on creep properties via a cluster formula approach

Chen

¹

,

Wang

²

,

Chen

³

et al. 2020

Sci Rep

View full text Add to dashboard Cite

The present work investigated the composition evolution of the TMS series of Ni-base single crystal (SC) superalloys in light of the cluster formula approach systematically. The cluster formula of SC superalloys could be expressed with $${[}\overline{{{\text{Al}}}} {-} \overline{{{\text{Ni}}}} 12{](}\overline{{{\text{Al}}}} {, }\overline{{{\text{Cr}}}} {)}m$$ [ Al ¯ - Ni ¯ 12 ] ( Al ¯ , Cr ¯ ) m , in which all the alloying elements were classified into three groups, Al series ($$\overline{{{\text{Al}}}}$$ Al ¯ ), Cr series ($$\overline{{{\text{Cr}}}}$$ Cr ¯ ), and Ni series ($$\overline{{{\text{Ni}}}}$$ Ni ¯ ). It was found that the total atom number (Z) of the cluster formula units for TMS series of superalloys varies from Z ~ 17 to Z ~ 15.5, and then to Z ~ 16 with the alloy development from the 1st to the 6th generation, in which the superalloys with prominent creep resistance possess an ideal cluster formula of $${[}\overline{{{\text{Al}}}} {-} \overline{{{\text{Ni}}}} 12{](}\overline{{{\text{Al}}}} 1.5\overline{{{\text{Cr}}}} 1.5{)}$$ [ Al ¯ - Ni ¯ 12 ] ( Al ¯ 1.5 Cr ¯ 1.5 ) with Z = 16. Similar tendency of composition evolution also appears in the PWA and CMSX series of SC superalloys. Typical TMS series of superalloys with prominent creep properties generally exhibit a moderate lattice misfit of γ/γ′ which could render alloys with appropriate particle size of cuboidal γ′ precipitates to acquire a maximum strength increment by precipitation strengthening mechanism. More importantly, the relationship between the lattice misfit (δ) of γ/γ′ and the creep rupture lifetime (tr) of superalloys was then established, showing a linear correlation in the form of lgtr–lg|δ|3/2 at both conditions of 900 °C/392 MPa and 1100 °C/137 MPa. Combined with the lattice misfit, the cluster formula approach would provide a new way to modify or optimize the compositions of Ni-base superalloys for further improvement of creep property.

show abstract

“…The same reflection type of the precipitate (220 TiC ) and an extra spot of compressed matrix planes (220 γ-def ) are marked in the picture. It is known that TiC carbide precipitates in "cube-to-cube "orientation and, due to a large mismatch between the precipitate and the matrix lattice (a γ = 0.360 nm, a TiC = 0.433 nm), precipitation causes strong strain around the particles [31,32]. Some of the carbides were surrounded with dislocation loops to reduce the elastic strain in the matrix [33].…”

Section: Transmission Electron Microscopymentioning

confidence: 99%

Influence of Higher Stabilization Temperatures on the Microstructure and Mechanical Properties of Austenitic Stainless Steel 08Ch18N10T

Janda

¹

,

Jeníček

²

,

Opatová

³

et al. 2023

Metals

View full text Add to dashboard Cite

Precipitation strengthening in titanium-stabilized austenitic stainless steels can improve the hot yield strength, as requested, e.g., for nuclear industry applications. The resulting properties depend mainly on the parameters of the heat treatment and previous forming. The influence of the heat treatment parameters on the development of the microstructure and mechanical properties was determined for steel 08Ch18N10T (GOST). Solution annealing and stabilization with different temperatures and holds were performed on the steel, which was, in delivered condition, stabilized at 720 °C. Heat-treated samples were subjected to static tensile testing at room temperature and at 350 °C, microstructural analysis using light, scanning electron and transmission electron microscopy focused on precipitates, and HV10 hardness testing. The strengthening mechanism and its dependence on the stabilization parameters are described. The results of the experiment show the influence of the state of the input material on the final effect of heat treatment—repeated heat treatment achieved lower-strength characteristics than the initial state, while almost all modes showed above-limit values for the mechanical properties. Stabilization temperatures of 720 to 800 °C were found to be optimal in terms of the achieved hot yield strength. At higher temperatures, slightly lower strengths were achieved, but at significantly shorter dwell times.

show abstract

Internal Mismatch Stresses in Nickel-Based Superalloys : A Finite Element Approach

Cited by 12 publications

References 14 publications

Investigation of a Ferrite/Silicon Nitride Composite Concept Aimed at Automotive Applications

Investigation of a Ferrite/Silicon Nitride Composite Concept Aimed at Automotive Applications

Composition rules of Ni-base single crystal superalloys and its influence on creep properties via a cluster formula approach

Influence of Higher Stabilization Temperatures on the Microstructure and Mechanical Properties of Austenitic Stainless Steel 08Ch18N10T

Contact Info

Product

Resources

About