Zr_0.8Ti_0.2Co alloy shows tremendous potential for handling hydrogen isotopes in fusion reactors. However, its severe cyclic fading remains a big challenge for achieving engineering application. Herein, we report a comprehensive study on hydrogenation phase transformation and structural evolution in cyclic stabilizing process of Zr_0.8Ti_0.2Co alloy. It is clarified that the stable capacity is provided by a metastable phase (Zr_0.8Ti_0.2CoH_1.4) because the cyclic reaction transforms from Zr_0.8Ti_0.2Co↔Zr_0.8Ti_0.2CoH₃ (heterogeneous structural phase transformation) into Zr_0.8Ti_0.2Co↔Zr_0.8Ti_0.2CoH_1.4 (homogeneous structural phase transformation). In addition, structural analysis reveals the cyclic hydrogenation phase transformation mechanism. The in situ ZrCo₂ and ZrH₂ phases compose a porous cage structure with remarkable mechanical property on the surface, which tightly restricts hydriding volume expansion of ZrCo phase. Thus, generation of ZrCoH₃ phase with higher volume expansibility (21%) is replaced by Zr_0.8Ti_0.2CoH_1.4 phase (ΔV = 8%). The sparkling concept of forming metastable phase within homogeneous structural phase transformation reaction will serve as a pioneer on cyclic optimization in energy storage materials.

Zr _0.8 Ti _0.2 Co合金显示出在聚变反应堆中处理氢同位素的巨大潜力。然而，其严重的周期性衰落仍然是实现工程应用的巨大挑战。本文中，我们对Zr _0.8 Ti _0.2 Co合金的循环稳定过程中的氢化相变和结构演变进行了全面的研究。据澄清，稳定的容量由亚稳相（锆提供_0.8的Ti _0.2治疗之环_1.4），因为由Zr环状反应变换_0.8的Ti _0.2 Co↔Zr _0.8的Ti _0.2治疗之环₃（异质结构相转变）转换成的Zr _0.8的Ti _0.2 Co↔Zr _0.8的Ti _0.2治疗之环_1.4（均相结构相变换）。另外，结构分析揭示了环状氢化相变机理。该原位ZrCo ₂和ZRH _2个相组成与表面，其紧紧限制ZrCo相的氢化体积膨胀上显着的机械性能的多孔笼状结构。因此，用Zr _0.8 Ti _0.2 CoH _1.4代替了具有更高体积膨胀性（21％）的ZrCoH ₃相的生成。相（ΔV= 8％）。在均相结构相变反应中形成亚稳态相的闪耀概念将成为储能材料循环优化的先驱。