Ti60合金微观组织演变及力学性能预测的模拟研究

Simulation Study on Microstructure Evolution and Mechanical Property Prediction of Ti60 Alloy

  • 摘要: 通过模拟的方法对Ti60合金的组织及力学性能进行预测已成为材料研发的重要手段。本研究将Ti60合金折算为Ti-Al-Mo三元合金体系,通过建立相应的热动力学数据框架和多相场动力学模型,描述了Ti60合金双态微观组织的演变,并结合晶体塑性有限元模型评估了其力学性能。研究表明,随着热处理温度升高,体系内初生与次生α相的体积分数均降低,内应力对变体的选择作用增强。同时,Al元素在α相中的富集程度提高,而Mo元素相对贫乏。在双态微观组织变形过程中,β相是高应力分配相,次生α相周围易发生应力集中,且初生α相的平均应变显著高于次生α相的。随着温度升高,片层增厚,变体选择效应增强,导致应力协调性和分布均匀性降低,加剧了应变分布的不均匀性,使合金塑性降低。本研究为通过热处理工艺优化Ti60合金的显微组织和力学性能提供了理论依据。

     

    Abstract: To predict the microstructure and mechanical properties of the Ti60 alloy by the simulation method is an important way for the material development. In this study, Ti60 alloy is converted into a Ti-Al-Mo ternary alloy based on its composition. On the foundation of establishing a quantitative thermodynamic data framework for Ti-Al-Mo alloys, a multiphase field kinetics model is developed to describe the bimodal microstructure evolution of Ti60 alloy, and by utilizing crystal plasticity finite element models, the mechanical properties of the microstructure obtained through phase field simulations are evaluated. The research reveals that with the increasing of heat treatment temperature, the volume fraction of the primary and secondary α phase decreases, and the the role of internal stress in variant selection is enhanced. Concurrently, the enrichment of Al within the α phase increases, while the depletion of Mo decreases gradually. During the bimodal deformation process, the β phase acts as the phase with high stress distribution, causing stress concentration around smaller secondary α phases. The average strain in primary α phases is notably higher than that in the secondary α phases. As the temperature rises, the lamellar thickens within the microstructure and the variant selection effects intensify, reducing the alloy’s stress coordination and uniform distribution, exacerbating uneven strain distribution and differential allocation characteristics, thereby decreasing alloy ductility. This study provides a model and data foundation for regulating the microstructural morphology of Ti60 alloy through heat treatment regimes.

     

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