Architecting micro-and nanoscale heterostructure for exceptional strength-ductility synergy in additively manufactured titanium alloy

IF 12.8 1区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Plasticity Pub Date : 2025-09-21 DOI:10.1016/j.ijplas.2025.104488

Fu Chen , Huaqiang Liu , Yuanfei Han , Jiaming Zhang , Xiaoyan Wang , Yongqiang Ye , Chunyu Shen , Yimin Zhuo , Jianwen Le , Guangfa Huang , Weijie Lu , Di Zhang

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引用次数: 0

Abstract

Strength-ductility trade-off in additively manufactured titanium alloys has been a critical bottleneck, significantly limiting their engineering applications. Our work demonstrated that this dilemma was overcome by tailoring a hierarchical heterostructure (HHS) in laser-directed energy deposited titanium alloy (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si). The designed HHS consisted of coarse micro-sized α phases (α_p, soft region) and ultrafine nano-sized α precipitates (α_s, hard region), generating hierarchical heterointerfaces including microscale α_p/β_t and nanoscale α_s/β_r interfaces. The HHS enhanced the total elongation to failure by 476.2 % without sacrificing strength compared to the conventional α-β lamella structure, achieving exceptional strength-ductility synergy. Micro/nano-scale mechanical deformation analyses showed that hetero-deformation between coarse α_p and ultrafine α_s regions caused noticeable accumulation of geometrically necessary dislocations (GNDs) at heterointerfaces, inducing the pronounced hetero-deformation induced (HDI) strengthening effect on the soft α_p, and the HDI hardening effect improving ductility. The HDI stress facilitated the formation and growth of dislocation networks in soft α_p, promoting the accumulation of interfacial GNDs, enhancing the HDI hardening effect. Compared to single-level α/β interfaces, hierarchical heterointerface generated higher GND density with a dual-gradient distribution, further improving the HDI stress and producing multiscale HDI hardening. This resultant high HDI stress activated high-proportioned pyramidal 〈c + a〉 slip modes with significant increment of GND density, overcoming deformation incompatibility. Moreover, hierarchical heterointerface exhibited a multi-scale crack buffering effect, synergistically contributing to the excellent ductility. Finally, a two-level homogenization model was established to comprehensively elucidate the intrinsic strengthening-toughening mechanism of the HHS. This work provided theoretical guidance for developing additively manufactured titanium alloys with high-performance.

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在增材制造钛合金中构建微纳米异质结构以实现卓越的强度-延性协同作用

增材制造钛合金的强度与延性权衡一直是制约其工程应用的关键瓶颈。我们的工作表明，通过在激光定向能沉积的钛合金（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si）中定制分层异质结构（HHS）可以克服这一难题。设计的HHS由粗大的微尺度α相（αp，软区）和超细的纳米尺度α相（αs，硬区）组成，形成了微尺度αp/βt和纳米尺度αs/βr界面的分层异质界面。与传统的α-β片层结构相比，HHS在不牺牲强度的情况下将总延伸率提高了476.2%，实现了优异的强度-延性协同效应。微纳尺度的力学变形分析表明，αp粗区和αs超细区之间的异质变形导致异质界面上明显的几何必要位错（GNDs）积累，对软αp产生明显的异质变形诱导（HDI）强化作用，HDI硬化作用提高了塑性。HDI应力促进了软αp中位错网络的形成和生长，促进了界面GNDs的积累，增强了HDI硬化效果。与单能级α/β界面相比，分层异质界面以双梯度分布产生更高的GND密度，进一步提高了HDI应力，产生了多尺度HDI硬化。由此产生的高HDI应力激活了高比例的锥体<；c+ >；滑移模式，并显著增加GND密度，克服了变形不相容。此外，分层异质界面具有多尺度的裂纹缓冲作用，协同促进了优异的延性。最后，建立了两级均匀化模型，全面阐明了HHS的内在强韧机理。该工作为开发高性能增材钛合金提供了理论指导。

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来源期刊

International Journal of Plasticity 工程技术-材料科学：综合

CiteScore

15.30

自引率

26.50%

发文量

256

审稿时长

46 days

期刊介绍： International Journal of Plasticity aims to present original research encompassing all facets of plastic deformation, damage, and fracture behavior in both isotropic and anisotropic solids. This includes exploring the thermodynamics of plasticity and fracture, continuum theory, and macroscopic as well as microscopic phenomena. Topics of interest span the plastic behavior of single crystals and polycrystalline metals, ceramics, rocks, soils, composites, nanocrystalline and microelectronics materials, shape memory alloys, ferroelectric ceramics, thin films, and polymers. Additionally, the journal covers plasticity aspects of failure and fracture mechanics. Contributions involving significant experimental, numerical, or theoretical advancements that enhance the understanding of the plastic behavior of solids are particularly valued. Papers addressing the modeling of finite nonlinear elastic deformation, bearing similarities to the modeling of plastic deformation, are also welcomed.