Alloying and strain hardening of high-entropy membrane storage nano and crystalline alloys

Abstract

The article presents both molecular dynamics calculations of binary Fe–Ni alloys and experimental studies of Ti and Co alloyed nanocrystalline alloys with a B2–Ti(Fe, Co) matrix structure as well as bcc-(Nb, Ti) and B2– eutectic phases Ti(Fe, Co). The structures of membrane alloys based on Fe–Ni (arrangement of atoms in coordination polyhedra and interatomic distances between atoms), as well as the kinetics of hydrogen - diffusion and permeability have been studied. It is shown that in the membranes of alloyed alloys with the substitution of Ni for cobalt Fe35-XCoXTi35Nb30, with an excess of Fe than for cobalt, mechanical brittleness is manifested in the B2–TiFe phase, and the plasticity of the B2 phase also decreases. At the same time, the resistance to an increase in hydrogen absorption is also weakened, up to mechanical destruction of membranes, so that in high-entropy alloys Fe0,2Ni0,2Cr0,2Co0,2Mn0,2, Fe0,2Co0,2Cr0,2 Ti0,2Al0,2 Fe and Co in equal parts. Other intermetallic alloys are also promising, having more complex compositions with high or moderate entropy, for example, Zr0,2Ti0,2Nb0,2V0,2Co0,2 and Zr0,2Ti0,2Ta0,2V0,2Co0,2, in addition to hydrogen evolution, also have storage properties. Within the framework of molecular dynamics, the effect of strain hardening of membrane HEA alloys is experimentally presented - the mechanism of synergy with multiple deformation. As a result of such hardening, a partial transformation of the austenitic phase into a martensite phase occurs with the formation of twinning in their fcc/hcp grains and the formation of a two-phase matrix structure.

Keywords

• nanocrystalline alloys
• modeling
• alloying
• work hardening
• matrix structure
• eutectic phases
• high-entropy alloys
• austenite
• martensite
• membranes
• hydrogen
• hydrides