Fracture of convoluted and lamellar α2 + γ TiAl alloys

Barbi, Nicolas; Diologent, Frédéric; Goodall, Russell; Mortensen, Alicja

doi:10.1016/j.intermet.2011.11.001

Cited by 12 publications

(2 citation statements)

References 39 publications

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“…However, more atomistic insights are still necessary to understand the thermomechanical deformation behavior of a single lamellar interface in γ-TiAl at elevated service temperatures. Our understanding of the combined microscopic effects and mechanisms occurring in plasticity and fracture of TiAl still remains limited (Appel et al, 2016), even though some small-scale testing has been conducted revealing the failure mechanisms in the microstructure (Werwer et al, 2007;Barbi et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the High-Temperature Separation Behavior of Lamellar Interfaces in γ-Titanium Aluminide Under Tensile Loading by Molecular Dynamics

2021

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γ-titanium aluminide (TiAl) alloys with fully lamellar microstructure possess excellent properties for high-temperature applications. Such fully lamellar microstructure has interfaces at different length scales. The separation behavior of the lamellae at these interfaces is crucial for the mechanical properties of the whole material. Unfortunately, quantifying it by experiments is difficult. Therefore, we use molecular dynamics (MD) simulations to this end. Specifically, we study the high-temperature separation behavior under tensile loading of the four different kinds of lamellar interfaces appearing in TiAl, namely, the γ/α2, γ/γPT, γ/γTT, and γ/γRB interfaces. In our simulations, we use two different atomistic interface models, a defect-free (Type-1) model and a model with preexisting voids (Type-2). Clearly, the latter is more physical but studying the former also helps to understand the role of defects. Our simulation results show that among the four interfaces studied, the γ/α2 interface possesses the highest yield strength, followed by the γ/γPT, γ/γTT, and γ/γRB interfaces. For Type-1 models, our simulations reveal failure at the interface for all γ/γ interfaces but not for the γ/α2 interface. By contrast, for Type-2 models, we observe for all the four interfaces failure at the interface. Our atomistic simulations provide important data to define the parameters of traction–separation laws and cohesive zone models, which can be used in the framework of continuum mechanical modeling of TiAl. Temperature-dependent model parameters were identified, and the complete traction–separation behavior was established, in which interface elasticity, interface plasticity, and interface damage could be distinguished. By carefully eliminating the contribution of bulk deformation from the interface behavior, we were able to quantify the contribution of interface plasticity and interface damage, which can also be related to the dislocation evolution and void nucleation in the atomistic simulations.

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Section: Introductionmentioning

confidence: 99%

Quantifying the High-Temperature Separation Behavior of Lamellar Interfaces in γ-Titanium Aluminide Under Tensile Loading by Molecular Dynamics

2021

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“…A new class of TiAl alloys showing an interesting balance of properties has been recently developed and obtained by thermal treating cast TiAl alloys. In these alloys each grain contains α2 lamellae embedded in γ, creating a "convoluted" structure [14]. One of these novel alloys displays fracture toughness values of 13 at room temperature and 19 at 923 K. Considering the bad workability of TiAl intermetallic alloys, toughness tests are often carried out according to the ASTM E1820 standard by using samples tested in 3-point bending.…”

Section: Introductionmentioning

confidence: 99%

Fracture toughness of TiAl-Cr-Nb-Mo alloys produced via centrifugal casting

Brotzu

Felli²,

Pilone³

2012

Frattura Ed Integrità Strutturale

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Fracture toughness of a TiAl base intermetallic alloy has been investigated at room temperature. The Ti-48Al-2.5Cr-0.5Nb-2Mo (at. %) alloy produced via centrifugal casting exhibits fine nearly lamellar microstructures, consisting mainly of fine lamellar grains, together with a very small quantity of residual β phases along lamellar colony boundaries. In order to determine the alloy fracture toughness compact tension specimens were tested and the results were compared with those available in literature.

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