低循环疲劳NiTi基超弹合金微纳米尺度相设计的研究进展

    Research Progress on Phase Design at Micro and Nano Scales of Low-cycle-fatigue NiTi Based Superelastic Alloys

    • 摘要: 形状记忆合金功能特性的循环疲劳问题是制约其长期服役模式下功能应用的共性关键问题。反复加载-卸载条件下应力诱发奥氏体的塑性变形会影响应力驱动超弹性的循环稳定性。近期的研究进展表明,通过合理的成分设计可以引入合适体积分数的第二相,进而显著提升合金超弹响应的循环稳定性。本文综述了Ni-Ti基合金薄膜、增材制造块体合金和大塑性变形合金微柱三类低循环疲劳超弹合金的相设计,分析了合金的基体相和第二相的相结构、相界面、相分数、相模量等特征,并对低循环疲劳相设计策略的潜在应用进行了展望。

       

      Abstract: The cycle fatigue of functional characteristics of shape memory alloys is a general key issue in restricting its functional application under long-term service conditions.Under cyclic loading-unloading conditions, stress-induced plastic deformation in austenite affects the cycling stability of stress-driven superelasticity.The recent research advances show that reasonable alloy design results in the introduction of a second phase with an appropriate volume fraction, which can dramatically enhance the cyclic stability of superelastic response.In this article, the phase design strategy of three low-cycle-fatigue NiTi based superelastic alloys was reviewed, ranging from NiTi based alloy film, additive manufactured bulk alloy to severely plastic deformed alloy pillar.The phase structure, phase interface, volume fraction and modulus of both the matrix phase and the second phase in each alloy were discussed.Finally, the potential application fields of the low-cycle-fatigue phase design strategy were highlighted.

       

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