大量间隙固溶作为高熵合金的强化途径

Substantial Interstitial Solid Solutions as a Route to High-Strength High-Entropy Alloys

摘要: 间隙固溶能够引发显著晶格畸变并有效强化金属，然而传统合金设计受限于固有的热力学固溶度极限，难以容纳足量间隙原子。同时，间隙含量的增加往往诱发脆性相析出并损害塑性，致使强度与塑性的协同提升长期面临挑战。在此，我们提出大量间隙固溶合金概念，将超高冷却速率的磁控溅射非平衡沉积与大晶格畸变的Co-Cr-Ni高熵合金相结合，成功突破B与N元素的热力学溶解限制。衍射分析证实，间隙原子持续撑开晶格，晶格失配随固溶量增加由2.1%扩大至3.7%，直至接近固溶极限。该近极限间隙固溶状态使合金硬度与杨氏模量分别达到16.7 GPa和195 GPa，较无间隙原子合金提升26.5%和23.4%，同时抗蠕变性能显著优化，蠕变位移降至1.2 nm。锯齿流变分析揭示其内在机制，高密度间隙原子一方面大幅提升位错形核能垒，另一方面促进位错增殖并强化应变硬化，从而协同驱动强度与塑性的同步改善。本研究颠覆了依赖微量间隙掺杂的传统设计范式，为开发兼具超高强度与优异塑性的新一代高性能合金提供了清晰的成分与结构设计策略。

Abstract: Interstitial solid solutioning induces pronounced lattice distortion and effectively strengthens metals, yet conventional alloy design remains constrained by inherent thermodynamic solubility limits, which restrict the incorporation of sufficient interstitial atoms. Raising interstitial content often triggers brittle phase precipitation and degrades ductility, making the simultaneous enhancement of strength and plasticity a long-standing challenge. Here we propose the concept of substantial interstitial solid solution (SISS) alloys by integrating ultra-high-cooling-rate magnetron sputtering non-equilibrium deposition with highly distorted Co-Cr-Ni high-entropy alloy, successfully transcending the thermodynamic dissolution limits of B and N. Diffraction analyses confirm that interstitial atoms continuously expand the lattice, with lattice mismatch enlarging from 2.1% to 3.7% as solute content increases until approaching the solubility limit. This near-limit interstitial solid solution state elevates hardness and Young’s modulus to 16.7 GPa and 195 GPa respectively, representing enhancements of 26.5% and 23.4% over the interstitial-free alloy, while improving creep resistance with creep displacement reduced to 1.2 nm. Serrated flow analyses unravel the underlying mechanisms, where high-density interstitial atoms substantially raise the dislocation nucleation barrier and simultaneously promote dislocation multiplication and strain hardening, synergistically driving concurrent improvements in strength and plasticity. This work disrupts the conventional paradigm of trace interstitial doping and establishes a clear compositional and structural design strategy for developing next-generation high-performance alloys combining ultra-high strength with excellent ductility.