Exploring the brittle-to-ductile transition and microstructural responses of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"> <mml:mrow> <mml:mi>γ</mml:mi> </mml:mrow> </mml:math> −TiAl alloy with a crystal plasticity model

This study developed a crystal plasticity finite element model that couples dislocation density and twinning evolution. By employing Bayesian optimization to identify the crystal plasticity parameters, the model simulates the tensile behavior of γ −TiAl alloys, thereby revealing the micro-mechanisms underlying the brittle-to-ductile transition in γ −TiAl alloys. • A crystal plasticity finite element model based on dislocation density and twinning evolution was constructed. • The crystal plasticity simulation parameters were identified using the Bayesian optimization method due to its efficiency and accuracy. • The simulations revealed that the increase in temperature significantly increase the plasticity of the α 2 phase, thereby achieving the brittle-to-ductile transition. γ −TiAl alloy, with its high specific strength and creep resistance, is ideal for aerospace engines and gas turbines, but its brittleness poses significant manufacturing and processing challenges. To address these issues, this study employs a crystal plasticity finite element method incorporating dislocation and twinning to analyze the brittle-to-ductile transition behavior of γ −TiAl alloy at different temperatures. Additionally, the Bayesian optimization methods are employed to efficiently and accurately obtain parameters related to numerical calculations of crystal plasticity. The results indicate that at room temperature, the high activation resistance of the slip systems in the α 2 phase leads to limited slip activity, resulting in poor plasticity. However, at 750 °C and 850 °C, the strength of the slip systems decreases significantly, allowing more α 2 phase lamellae in the γ -TiAl alloy to undergo greater plastic deformation. This enhancement in the plastic deformation capacity of the α 2 phase lamellae reduce the overall deformation incompatibility in the TiAl alloy, thereby improving the overall ductile of the γ -TiAl alloy.