The effect of copper doping on martensite shear stress in porous TiNi (Mo, Fe, Cu) alloys

The properties of alloys based on porous nickel-titanium (TiNi) with copper additives have bee

The equilibrium of martensite shear stress at phase transitions in TiNi-based alloy

Thermoelastic martensitic transformations play a fundamental role in the shape memory effect and related phenomena. Owing to their unique crystallographic and thermomechanical behaviour, martensitic transformations have generated considerable research in the areas of crystallography, thermodynamics and mechanical behaviour. In the area of thermodynamics a theoretical approach is now added which provides the basis for thermoelastic behaviour through consideration of the Gibbs energy change. In this paper, the interrelation of internal elastic stresses and martensite shear stresses in phase transitions has been defined. A thermoelastic stress equilibrium equation for a wide range of martensitic transformation temperatures has been presented. On the basis of the calculations made, an estimation of dislocation defects formation energy for the TiNi-based alloy has been made. For TiNi-based composition made of TN-10 brand alloy, commercially produced for medical goals, the energy of vacancy formation is about 0.06 kcal/mol. The study and calculations are shown to make clear, using a new approach, the considering of phase transitions in terms of external and internal stresses

Study of structural features of porous TiNi-based materials produced by SHS and sintering

Structural properties of porous TiNi-based materials produced by SHS method and sintering have been investigated. The material having different pore wall surface topography, porosity and pore size distribution was shown to be produced depending on the powder metallurgy method for porous TiNi-based alloy. All the materials having porosity of 55-70%, mean pore size 90-150 μm, as well as normal pore size distribution are most preferable. Ultimate strength and breaking point were determined to depend on porosity, pore size distribution, pore intersections and phase chemical composition of the material. Strength properties of the sintered alloy are twice as much compared to the SHS-produced ones due to homogeneity of its macrostructure, low chemical heterogeneity and TiNi3 precipitations strengthening the TiNi matrix.</jats:p

The structure and properties of functional titanium nickelide-based TN-10, TN-20, and TN-1V alloys

The interrelation among the structural features, martensitic transformation characteristics, and physical-mechanical properties of functional titanium nickelide-based TN–10, TN–20, and TN–1V alloys is investigated. Martensitic transformations in a TN–10 alloy at temperatures of 273 and 298 K are found to develop at lower martensite shear stresses than in TN–20 and TN–1V alloys. This is due to the internal structure formed in the production of the material. The degree of ultimate strain and the magnitude of ultimate stress for each of the alloys depend on the state of the matrix at a pre-assigned deformation temperature and on the contribution of the martensitic transformation mechanisms of deformation under applied load. The structure formed and the plastic component of deformation are shown to exert a dramatic effect on the type and characteristics of fracture

The effect of copper doping on martensite shear stress in porous TiNi (Mo, Fe, Cu) alloys

The properties of alloys based on porous nickel-titanium (TiNi) with copper additives have bee

The structure and properties of functional titanium nickelide-based TN-10, TN-20, and TN-1V alloys

The interrelation among the structural features, martensitic transformation characteristics, and physical-mechanical properties of functional titanium nickelide-based TN–10, TN–20, and TN–1V alloys is investigated. Martensitic transformations in a TN–10 alloy at temperatures of 273 and 298 K are found to develop at lower martensite shear stresses than in TN–20 and TN–1V alloys. This is due to the internal structure formed in the production of the material. The degree of ultimate strain and the magnitude of ultimate stress for each of the alloys depend on the state of the matrix at a pre-assigned deformation temperature and on the contribution of the martensitic transformation mechanisms of deformation under applied load. The structure formed and the plastic component of deformation are shown to exert a dramatic effect on the type and characteristics of fracture

The equilibrium of martensite shear stress at phase transitions in TiNi-based alloy

Thermoelastic martensitic transformations play a fundamental role in the shape memory effect and related phenomena. Owing to their unique crystallographic and thermomechanical behaviour, martensitic transformations have generated considerable research in the areas of crystallography, thermodynamics and mechanical behaviour. In the area of thermodynamics a theoretical approach is now added which provides the basis for thermoelastic behaviour through consideration of the Gibbs energy change. In this paper, the interrelation of internal elastic stresses and martensite shear stresses in phase transitions has been defined. A thermoelastic stress equilibrium equation for a wide range of martensitic transformation temperatures has been presented. On the basis of the calculations made, an estimation of dislocation defects formation energy for the TiNi-based alloy has been made. For TiNi-based composition made of TN-10 brand alloy, commercially produced for medical goals, the energy of vacancy formation is about 0.06 kcal/mol. The study and calculations are shown to make clear, using a new approach, the considering of phase transitions in terms of external and internal stresses