亚稳β钛合金热压缩动态机械行为、组织演变与复原机制研究

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该文亮点：

测试了亚稳β钛合金TP1等温热压缩应力-应变曲线，计算了变形热，建立了基于Arrhenius模型的本构关系，揭示了TP1的热变形行为：低应变速率下，为动态再结晶；高应变速率下，动态再结晶被变形带取代。  

Highlights:

The isothermal compression stress-strain curves of a metastable β titanium alloy TP1 were tested. The deformation-producing heats were calculated. An Arrhenius constitutive model of TP1 was established. The hot deformation behavior of TP1 was revealed: the dynamic recrystallization (DRX) dominates the hot deformations at low strain rates, while the DRX is replaced by the deformation bands at high strain rates.

亚稳β钛合金强度高、密度低，已部分替代高强钢，用于制造飞机起落架，实现了飞机大幅减重。然而，当前应用的亚稳β钛合金依然存在强度与塑性难以兼得的矛盾：当强度超过1.5 GPa后，塑性急剧下降（一般＜5%），导致其加工性与服役可靠性较差，限制了其进一步广泛应用。该文针对上述问题，开展了亚稳β钛合金TP1等温热压缩变形研究，揭示其热机械加工行为，对于该合金大尺寸构件生产及其在轻量化机械系统上的应用具有重要意义。

南京理工大学陈光院士团队在《国际机械系统动力学学报（英文）》（International Journal of Mechanical System Dynamics, IJMSD）发表的“亚稳β钛合金热压缩动态机械行为、组织演变与复原机制研究”论文，通过等温热压缩测试和EBSD组织表征等手段，研究了亚稳β钛合金TP1的动态机械行为、组织演变规律与动态复原机制。结果表明，压缩应力-应变曲线表现出不连续屈服现象，流变应力随温度的降低或应变速率的增加而增大。流变行为表现出显著的相区依赖性：在α+β两相区，变形激活能Q=288 kJ/mol，在β单相区，变形激活能Q=194 kJ/mol，接近β相的自扩散激活能。不同相区内建立的本构方程很好地描述和预测了流变应力，验证了模型的可靠性。EBSD组织表征显示，动态再结晶程度随应变速率增加逐渐降低，高应变速率下，动态再结晶被变形带取代。研究结果揭示了亚稳β钛合金TP1的热变形行为。

Abstract:

Metastable β titanium alloys are promising materials for lightweight and energy-efficient applications due to their high strength and low density. In this regard, parts of them have successfully replaced some high-strength steels to fabricate the aircraft landing gear, achieving large weight reduction in aircraft. However, as a matter of fact, the current use of metastable β titanium alloys is limited largely due to the stubborn conflict between strength and ductility. When the strength of these alloys exceeds 1.5 GPa, the ductility is often less than 5%, which not only diminishes their machinability and service reliability but also constrains their widespread applications. Regarding this problem, we carried out the isothermal hot compression tests for a metastable β titanium alloy TP1, which revealed its thermal-mechanical processing (TMP) behavior and thus guiding its production of large critical structural components in lightweight mechanical systems.

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《国际机械系统动力学学报（英文）》（International Journal Mechanical System Dynamics, IJMSD ）由来自12个国家的15位院士、14位国际学会主席、13位其他国际期刊主编等53位科学家和国际出版巨头美国Wiley出版社合作创立。IJMSD 旨在为用机械系统动力学科学与技术为提升现代装备设计、制造、试验、评估和使用全生命周期性能提供先进的理论、软件、方法、器件、标准，为全球科学家和工程专家提供广泛的机械系统动力学国际交流平台。IJMSD 强调从“系统”视角及系统级工具理解动力学，所涉及的机械系统不仅包括各种不同尺度的机械系统和结构，还包括具有多物理场/多学科特征的综合机械系统。