Structure and Physical-Mechanical Properties of a Nb–Ti Alloy after Different Kinds of Mechanical-Thermal Impacts

Abstract

The work presents experimental results on influence of five regimes of mechanical-thermal treatments (MTT), including different types of deformation (extrusion, drawing, draft, extrusion, deformation under quasi-comprehensive compression and their combination) on physical and mechanical as well as structural characteristics of NT-50 alloy. The dependences of the shear modulus at 20–400°C, strength characteristics at 20°C, temperature dependences of internal friction and relative resistivity within the 20–450°C after all MTT regimes are measured. It is shown that shear modulus and strength characteristics of HT-50 alloy have qualitatively different dependences on deformation degree, and hence on concentration of strain defects and quantity of α-Ti phase precipitated of β-solid solution. According to the results of measurements of temperature dependences of internal friction and relative resistivity, the levels of internal stresses in HT-50 alloy after different MTT regimes are determined. It is revealed that during the process of deformations along different directions (DDD) at 20 and 400°C, relaxation processes resulting to reduction in the internal stress levels in the alloy are occurring. The mechanisms of influence of different MTT regimes on physical and mechanical properties of NT-50 alloy are discussed.

Keywords