Analysis of deformation mechanism and temperature dependence of 3D printed TiAl nano-polycrystalline alloys based on molecular dynamics

doi:10.13251/j.issn.0254-6051.2021.11.001

Abstract

Abstract: By using the results from TEM observation and molecular dynamic simulation, the deformation behaviour and its temperature dependence of the 3D printed Ti-6Al-4V alloys were investigated. The results show that, the temperature plays a key role in the competition of deformation mechanisms of the TiAl nano-polycrystalline alloys. When the temperature is lower than 800 K, the single-phase TiAl nano-polycrystalline alloy with average grain size of less than 8.3 nm has dislocation movement first, and the stacking faults remain in the grains and form a staggered structure. At the same time, large grains (≥8.3 nm) provide enough space for dislocation movement, and stacking faults are rarely formed in the grains. In the dual-phase TiAl+Ti₃Al nano-polycrystalline alloy, the delivery of stacking faults is the main deformation mechanism of low strain (ε<18.0%) TiAl grains, and the Ti₃Al grains maintain their original structure. When the strain(ε) exceeds 18.0%, the dislocations in the Ti₃Al grains begin to move and form stacking faults. When the temperature is over 800 K, Ti and Al atoms are in a high-energy state, and the main deformation mechanism is related to the slip boundary with an amorphous structure. The amorphous slip boundary and recrystallization are the most important characteristics of the microstructure deformation of the dual-phase TiAl+Ti₃Al nano-polycrystalline alloy.

Key words: TiAl alloy, 3D printing, deformation mechanism, molecular dynamics

CLC Number:

TG146.2

Li Pengtao, Luo Xian, Chen Jianxin. Analysis of deformation mechanism and temperature dependence of 3D printed TiAl nano-polycrystalline alloys based on molecular dynamics[J]. Heat Treatment of Metals, 2021, 46(11): 1-8.

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