Mechanical Properties of Novel Arc-Sprayed Partially Amorphous Iron-Based Alloys Under Cryogenic Temperature and Hydrogen Influence

Previous own works revealed that novel partially amorphous Fe-based alloys have a combination of properties that are beneficial for the application in liquid hydrogen (LH2) tanks, such as low thermal diffusivity, little porosity, and good adhesion. The influence of cryogenic temperatures or hydrogen on coating tensile strength, on the other hand, has not been investigated yet for this material. However, this is crucial for the long-term durability of the coatings under hydrogen and other alternative fuels. Thus, in this work, tubular coating tensile (TCT) tests were performed at room temperature, cryogenic temperatures and after hydrogen charging. For this, a methodology for hydrogen charging was developed to identify a possible regime being sufficient for inducing a measurable amount of hydrogen. Subsequently, the fracture surfaces were evaluated analytically, optically and profilometrically. Under cryogenic conditions, a significant increase in tensile strength and finer structures of the fracture surfaces were observed. The TCT tests with ex-situ hydrogen charging revealed a small reduction in tensile strength and ductility compared to specimens tested at room temperature, proven by the coarse structure of the fracture surface.