Change in the Crystallographic Texture of the Martensitic Phase in Superelastic Ti–Zr–Nb Alloys with Increasing Tensile Strain

Superelastic alloys based on Ti–Zr–Nb are low-modulus biocompatible alloys for medical applications. We analyzed the regularities of the development of martensitic transformations (MT) β (bcc) → α′′ (orthorhombic lattice) in Ti–(17–19)Zr–(14–15)Nb (at.%) alloys, where α′′-phase arises under the influence of tensile or compressive stress. The crystallographic texture of β-titanium alloys was well studied. However, this is precisely what determines the recoverable strain in the material. Phase analysis using synchrotron radiation showed that the MT begins at 1% deformation, and at 1.5% the martensite lines are clearly distinguishable. The orientational dependences of the formation of domains of the martensite phase were studied using generalized direct pole figures. The main texture components of the cold rolled up to 97% and then recrystallized foils are {221}〈114〉 and {100}〈011〉. Under tensile deformation up to 1.4%, α′′-phase domains with the orientation (100)[001] is formed from β-grains compressed along the normal direction of the foil. With an increase in the degree of deformation to 1.6%, in addition to the main texture component, the second texture component appears. Its orientation depends on the direction of application of the external stress: (001)[110] in tension along the rolling direction and (\(\overline{1 }\)05)[501] in tension in the transverse direction.