Futuristic technologies such as morphing aircrafts and super-strong artificial muscles depend on metal alloys being as strong as ultrahigh-strength steel yet as flexible as a polymer^1,2,3. However, achieving such ‘strong yet flexible’ alloys has proven challenging^4,5,6,7,8,9 because of the inevitable trade-off between strength and flexibility^5,8,10. Here we report a Ti–50.8 at.% Ni strain glass alloy showing a combination of ultrahigh yield strength of σ_y ≈ 1.8 GPa and polymer-like ultralow elastic modulus of E ≈ 10.5 GPa, together with super-large rubber-like elastic strain of approximately 8%. As a result, it possesses a high flexibility figure of merit of σ_y/E ≈ 0.17 compared with existing structural materials. In addition, it can maintain such properties over a wide temperature range of −80 °C to +80 °C and demonstrates excellent fatigue resistance at high strain. The alloy was fabricated by a simple three-step thermomechanical treatment that is scalable to industrial lines, which leads not only to ultrahigh strength because of deformation strengthening, but also to ultralow modulus by the formation of a unique ‘dual-seed strain glass’ microstructure, composed of a strain glass matrix embedded with a small number of aligned R and B19′ martensite ‘seeds’. In situ X-ray diffractometry shows that the polymer-like deformation behaviour of the alloy originates from a nucleation-free reversible transition between strain glass and R and B19′ martensite during loading and unloading. This exotic alloy with the potential for mass producibility may open a new horizon for many futuristic technologies, such as morphing aerospace vehicles, superman-type artificial muscles and artificial organs.

变形飞机和超强人造肌肉等未来技术依赖于像超高强度钢一样坚固、像聚合物一样灵活的金属合金^1,2,3 。然而，事实证明，实现这种“坚固而柔韧”的合金具有挑战性^4,5,6,7,8,9 ，因为强度和柔韧性之间不可避免地需要权衡^5,8,10 。在这里，我们报道了一种Ti-50.8 at.% Ni应变玻璃合金，它具有σ _y ≈ 1.8 GPa的超高屈服强度和E ≈ 10.5 GPa的类聚合物超低弹性模量，以及超大的类橡胶弹性应变约8%。因此，与现有结构材料相比，它具有σ _y / E ≈ 0.17 的高灵活性品质因数。此外，它可以在-80°C至+80°C的宽温度范围内保持此类性能，并在高应变下表现出优异的抗疲劳性。该合金通过简单的三步热机械处理制成，可扩展到工业生产线，不仅通过变形强化实现超高强度，而且通过形成独特的“双晶种应变玻璃”微观结构实现超低模量，由嵌入少量排列整齐的 R 和 B19' 马氏体“种子”的应变玻璃基体组成。原位X射线衍射表明，合金的类聚合物变形行为源于加载和卸载过程中应变玻璃与R和B19'马氏体之间的无核可逆转变。 这种具有大规模生产潜力的奇异合金可能会为许多未来技术开辟新的视野，例如变形航空航天器、超人型人造肌肉和人造器官。