Effect of hydrogen on superelasticity of the titanium nickelide-based alloy

Hydrogen’s Effect on the Shape Memory Effect of TiNi Alloy Single Crystals

“…It is known that alloying with hydrogen atoms leads to a significant change in the properties of metals and alloys, for instance, to a decrease in plasticity at high hydrogen concentrations [1][2][3][4][5], to a decrease or increase in the shear modulus depending on the hydrogenation conditions [1,6], to a change in the strain hardening coefficient, etc. [7][8][9][10]. Hydrogen's effect on the deformation becomes especially noticeable when the system approaches the point of concentration or phase transition [1].…”

“…By now, hydrogen's effect on MT has been studied mainly on TiNi polycrystals [1,[3][4][5][6][7][8][22][23][24][25][26]. These studies have shown that hydrogen's effect on the mechanical and functional properties is determined by the state of hydrogen in the initial B2 phase (as metal hydrides or atoms in a solid solution), its concentration, and the type of initial phase itself (austenite or martensite) upon hydrogenation.…”

“…At low concentrations below 400 wppm (wppm represents weight part per million), hydrogen contributes to an increase in the plasticity of the martensite phase and superelasticity. When hydrogen concentrations are greater than 400 wppm, hydrogen reduces plasticity; suppresses shape memory; and in TiNi alloys with a one-stage B2-B19 MT, induces the R phase through stresses [1,[3][4][5][6][7][8][9][10][22][23][24][25][26]. Nevertheless, despite numerous experimental data, interest in studying the effect of hydrogen on the functional properties of binary TiNi alloys remains due to their wide use in the dental and medical fields [11,18,21].…”

Effect of Hydrogen Redistribution during Aging on the Martensitic Transformation and Superelasticity of Nanocrystalline TiNi Alloy

“…However, it is known that nickel titanium can absorb up to 40 atomic percent hydrogen atoms [1]. At present, it has been reliably established that the hydrogenation of wire samples made from nickel titanium based alloys leads to the degradation of their superelastic and mechanical properties (hydrogen embrittlement), regardless of the grain size [2,3].…”