Atomic-scale analysis of the duplex full lamellar TiAl alloys with different modulation cycles for the mechanical properties

M Zheng and BQ Yi and DF Qu and YP Xu and HM Zhang and ZH Sun and ZX Zhu, MATERIALS TODAY COMMUNICATIONS, 40, 109514 (2024).

DOI: 10.1016/j.mtcomm.2024.109514

In the duplex full lamellar TiAl alloys, the influences of the modulation cycles on the plastic deformation behavior and mechanism of the system are not clear. In this research, using a spherical indenter, molecular dynamics simulations of nanoindentation on gamma(TiAl)/alpha 2(Ti3Al) multilayers with different modulation cycles have been carried out with the aim of investigating the influence of the interface and the number of layers on the plastic deformation of the material and its strong hardening mechanism. A systematic analysis of indentation force, hardness and modulus of elasticity, defect evolution and stress-strain has been performed at the atomic level. The results show that when the modulation cycle lambda is large, as lambda decreases or the number of layers increases, the indentation force and the hardness of the alloys increase, showing the Hall-Petch phenomenon. There exists a critical value of the modulation cycle lambda, after which the two-phase boundary of the alloy forms steps and localized damage regions and becomes a new site for dislocation nucleation, resulting in a softening phenomenon as the indentation force and hardness decrease with the thickness of the lamellae, presenting an inverse Hall-Petch effect. For samples with different modulation cycles, the atoms of high localized stresses are mainly concentrated around the indentation region, and as the number of layers increases or the thickness of each layer decreases, the plastic deformation zone increases significantly and appears to expand to both sides.

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