The project “Stress Corrosion Cracking of Zr-based Bulk Metallic Glasses” (SCC of Zr-BMGs) within PP1594 mainly dealt with mechanical–corrosive interactions and failure of this class of metastable materials. It focused on one of the most application-relevant zirconium (Zr)-BMG, Vit(reloy) 105, with composition Zr₅₂.₅Cu₁₇.₉Ni₁₄.₆Al₁₀Ti₅ (at.%). Even though this BMG is known as an extraordinary glass former, the metallurgical processing is still a critical issue. In contrast to conventional processing, i.e., arc melting of master alloy ingots from single constituents, a different route using binary pre-alloys for the master alloys production was applied and led to superior mechanical properties upon mechanical testing under tensile and three-point-bending (3PB) conditions in air. As a reference and for a detailed understanding of failure, fracture, and cracking of Zr-based BMG in air, notched specimen 3PB experiments with in situ microscopic observation were done and the still controversial interpretation of the mechanical behavior of BMG in the framework of fracture mechanics was addressed. The specimen from the in situ 3PB tests served for transmission electron microscopy (TEM) investigations on the structural nature of shear bands in BMG on the atomistic scale. Altogether, complete crack paths could be observed and analyzed, and based on this, details of the shear band-driven crack growth are described. While in first SCC studies using a newly developed setup full cross section (3PB) bars were investigated, in recent in situ experiments, notched specimens were tested in 0.01 M NaCl, yielding strong evidence for a catastrophic failure due to hydrogen embrittlement (HE). The known susceptibility to pitting corrosion in halide-containing environments is only the initial stage for failure under SCC conditions. Once pitting is initiated, the local electrode potential is severely reduced. Further, the hydrolysis reaction of oxidized Zr⁴⁺ to zirconyl ions ZrO²⁺ during local BMG dissolution produces H⁺ and, thus, a local acidic environment that enables proton reduction and hydrogen absorption in the stressed BMG region. The peculiar failure and fracture surface characteristics as well as the proven local reduction of the pH value in the vicinity of the notch during in situ experiments clearly account for the proposed HE-SCC failure mechanism.

PP1594中的“ Zr基块状金属玻璃的应力腐蚀开裂”（Zr-BMGs的SCC）项目主要处理此类亚稳材料的机械腐蚀相互作用和破坏。它着眼于与应用最相关的锆（Zr）-BMG之一，Vit（reloy）105，其成分为Zr ₅₂。₅铜₁₇。₉镍₁₄。₆铝₁₀钛₅（在。％）。尽管这种BMG被称为非凡的玻璃成型机，但冶金工艺仍然是一个关键问题。与常规工艺（即从单一成分对母合金锭进行电弧熔化）相反，采用了使用二元预合金生产母合金的不同方法，在拉伸和三点弯曲下进行机械测试时，其机械性能优异。 （3PB）在空气中的条件。作为参考，并详细了解空气中Zr基BMG的失效，断裂和开裂，带缺口的3PB标本实验原位进行了显微镜观察，并探讨了在断裂力学框架内对BMG力学行为仍存在争议的解释。来自的标本原位3PB测试用于透射电子显微镜（TEM）研究原子能级BMG剪切带的结构性质。总之，可以观察和分析完整的裂纹路径，并在此基础上描述了剪切带驱动的裂纹扩展的细节。在首次使用新开发的装置进行SCC研究时，对全截面（3PB）钢筋进行了研究，最近原位实验中，缺口试样在0.01 M NaCl中进行了测试，为氢脆（HE）造成的灾难性破坏提供了有力证据。在含卤化物的环境中，点蚀的已知敏感性只是在SCC条件下失效的初始阶段。一旦开始点蚀，局部电极电势将大大降低。此外，在局部BMG溶解过程中，氧化的Zr ⁴⁺氧化为锆基离子ZrO ²⁺的水解反应产生H ⁺，从而产生局部酸性环境，该环境能够使质子还原并在应力BMG区域吸收氢。特殊的失效和断裂表面特性，以及已证实的缺口附近pH值的局部降低原位 实验清楚地说明了提出的HE-SCC失效机制。