Abstract:γ/γ interfaces drive plastic deformation in lamellar TiAl alloys. Due to the ordering and resulting tetragonal nature of γ phase, γ/γ twin interfaces exist as different variants, some of which exhibit coherency stresses or semicoherent interface structures. While geometric parameters, such as the lamella spacing and orientation, are explored extensively in experiments, the isolation of individual influence of different interfaces in a nanolamellar microstructure remains a challenge. Herein, the range of γ/γ in… Show more
“…These interface types are classically characterized by the lattice mismatch between both phase and resulting in the formation of interfacial defects, and do behave rather differently. In literature, the fcc/fcc coherent and semi-coherent interfaces are the most studied [6][7][8][9][10][11][12][13][14]. Besides, many experimental works and simulations are devote to incoherent interface [15][16][17][18][19][20][21].…”
Semi-coherent interfaces can have a strong influence on the mechanical behavior of bilayer systems, which is seen very clearly under indentation conditions where a well-defined plastic zone interacts directly with the interface. The main aim of this work is to study the influence of a semi-coherent bcc/bcc interface in the V/Fe bilayer system with molecular dynamics (MD) simulations. In particular, the influence of the V layer thicknesses on the apparent hardness of the bilayer system is investigated. Our results show that the deformation behavior of pure V and pure Fe resulting from the MD simulations is in good agreement with the literature. Moreover, the MD simulations reveal a significant enhancement of the hardness of V/Fe bilayer system for thinner vanadium layers, resulting from the crucial role of the semi-coherent interface as a barrier to dislocation propagation. This is seen from a detailed analysis of the interaction of mobile dislocations in the plastic zone with misfit dislocations in the interface. Our work shows that dislocation pile-ups at the interface and formation of horizontal shear loops are two key mechanisms dominating the rate and magnitude of plastic deformation and thus contributes to our understanding of mechanical behavior of bilayer systems with semi-coherent interfaces.
“…These interface types are classically characterized by the lattice mismatch between both phase and resulting in the formation of interfacial defects, and do behave rather differently. In literature, the fcc/fcc coherent and semi-coherent interfaces are the most studied [6][7][8][9][10][11][12][13][14]. Besides, many experimental works and simulations are devote to incoherent interface [15][16][17][18][19][20][21].…”
Semi-coherent interfaces can have a strong influence on the mechanical behavior of bilayer systems, which is seen very clearly under indentation conditions where a well-defined plastic zone interacts directly with the interface. The main aim of this work is to study the influence of a semi-coherent bcc/bcc interface in the V/Fe bilayer system with molecular dynamics (MD) simulations. In particular, the influence of the V layer thicknesses on the apparent hardness of the bilayer system is investigated. Our results show that the deformation behavior of pure V and pure Fe resulting from the MD simulations is in good agreement with the literature. Moreover, the MD simulations reveal a significant enhancement of the hardness of V/Fe bilayer system for thinner vanadium layers, resulting from the crucial role of the semi-coherent interface as a barrier to dislocation propagation. This is seen from a detailed analysis of the interaction of mobile dislocations in the plastic zone with misfit dislocations in the interface. Our work shows that dislocation pile-ups at the interface and formation of horizontal shear loops are two key mechanisms dominating the rate and magnitude of plastic deformation and thus contributes to our understanding of mechanical behavior of bilayer systems with semi-coherent interfaces.
The fracture behavior of the TiAl alloy is significantly affected by its nano-lamellar structure. However, further investigation is still required to fully comprehend how the initial crack configuration influences the lamellar TiAl’s deformation behavior. Although molecular dynamics simulations are a great way to study crack-tip interactions in interface dominated microstructures, the design of the simulation can have an impact on the behavior that is predicted. To shed light on this matter and at the same time to understand the impact of the specific interface structure, a systematic study of crack-tip interface interactions in nano lamellar two-phase TiAl was carried out. The type of interface and crack configuration were varied in these simulations to distinguish between the effects of the microstructure and the crack geometry. Results show that the semi-coherent pseudo twin (γ/PT) interface is the strongest barrier for crack propagation while the coherent true twin interface (γ/TT) is the weakest. After a thorough review of the contributing factors, it is evident that the orientation of the crack has a greater impact on its propagation than the aspect ratio of the crack. The stress shielding effectiveness of lamellar interfaces is strongly dependent on the crack configuration. However, regardless of the initial crack set-up, the coherent γ/TT interface appears to be the most effective interface in terms of shielding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.