Abstract
In recent years, multicomponent alloys with shape memory effects (SMEs), based on the ordered intermetallic compounds B2–TiNi, L21–Ni2MnGa, B2– and D03–Cu–Me (Me = Al, Ni, Zn), which represent a special important class of intelligent materials, have been of great interest. However, only a small number of known alloys with SMEs were found to have thermoelastic martensitic transformations (TMTs) at high temperatures. It is also found that most of the materials with TMTs and related SMEs do not have the necessary ductility and this is currently one of the main restrictions of their wide practical application. The aim of the present work is to design and develop multicomponent alloys with TMTs together with ways to improve their strength and ductile properties, using doping and advanced methods of thermal and thermomechanical treatments. The structure, phase composition, and TMTs were investigated by transmission- and scanning electron microscopy, as well as by neutron-, electron- and X-ray diffraction. Temperature measurements of the electrical resistance, magnetic susceptibility, as well as tests of the tensile mechanical properties and special characteristics of SMEs were also used. Temperature–concentration dependences for TMTs in the binary and ternary alloys of a number of quasi-binary systems were determined and discussed. It is shown that the ductility and strength of alloys required for the realization of SMEs can be achieved through optimal alloying, which excludes decomposition in the temperature range of SMEs’ usage, as well as via various treatments that ensure the formation of their fine- (FG) and ultra-fine-grained (UFG) structure.
Highlights
For more than 50 years, so-called intelligent binary and low-doped alloys based on titanium nickelide undergoing reversible thermoelastic diffusionless martensitic transformations (TMTs) attract great attention owing to the best combination of excellent structural and functional properties [1,2,3,4,5,6]
Ternary close to quasi-binary alloys based on the Ti–Ni–X system
Ternary close to quasi-binary alloys based on the Ti–Ni–X system and, for comparison, alloys of two actual systems Ni–Mn–Ga and Cu–Al–Ni were selected to investigate the possibilities for the creation of strength and ductile materials with TMTs and related SMEs due to multicomponent alloying and extreme external treatments
Summary
For more than 50 years, so-called intelligent (or smart) binary and low-doped alloys based on titanium nickelide undergoing reversible thermoelastic diffusionless martensitic transformations (TMTs) attract great attention owing to the best combination of excellent structural and functional properties [1,2,3,4,5,6] These alloys are distinguished by unusual effects of the thermomechanical shape memory (SMEs), pseudoelasticity (PE) and damping in combination with high-strength and ductile characteristics, excellent long-term strength and durability, corrosion resistance and biocompatibility. A unique key feature of the B2-austenite of titanium nickelide alloys in the pre-martensitic state is Materials 2019, 12, x FOR PEER REVIEW Materials. In this case, according to inelastic neutron scattering there is a significant
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