Physical metallurgy of Ti–Ni-based shape memory alloys

Shape memory alloys (SMAs) with high transformation temperatures can enable simplifications and improvements in operating efficiency of many mechanical components designed to operate at tem...

High temperature shape memory alloys

The super-elastic property of the Japanese NiTi alloy wire for use in orthodontics

Shape memory alloys, Part I: General properties and modeling of single crystals

Transformation pseudoelasticity and deformation behavior in a Ti-50.6at%Ni alloy

Superelasticity effects and stress-induced martensitic transformations in CuAlNi alloys

Successive stress-induced martensitic transformations and associated transformation pseudoelasticity in Cu-Al-Ni alloys

The Fracture of Cu–Al–Ni Shape Memory Alloy

The effect of heat treatments on martensitic transformations in monocrystalline Cu–14.1Al–4.2Ni (mass%) (alloy 1) and Cu–14.7Al–4.2Ni (mass%) (alloy 2) shape memory alloys has been investigated by means of differential scanning calorimetry measurements, optical microscopy and tensile tests of martensitic specimens. As a result, it was found in alloy 1 that not only transformation temperatures shifted but also thermally formed martensite changed from β1' to γ1' with heat treatment. Meanwhile, in alloy 2, the γ1' martensite was thermally formed regardless of heat treatment. To clarify the reason for the change of thermally formed martensite, equilibrium temperatures, To, for the β1_??_γ1' and β1_??_β1' transformations and their variation within heat treatment were estimated by utilizing previous data on stress-induced martensitic transformations and associated pseudoelasticity of the alloys (Trans. Jpn. Inst. Met., 28 (1987), 264). Consequently, by taking into consideration the variation of To temperatures and, in addition, supercooling neccessary for the nucleation of the γ1' and β1' martensites, the origin was successfully elucidated in terms of a simple scheme that the martensite phase with the highest MS temperature changed from the β1' to the γ1' with heat treatment. Applicability of this scheme was discussed on similar phenomena occurred in other alloy systems in which martensite phases changed with chemical composition.

/pdf/effect-of-heat-treatments-on-thermally-formed-martensite-2g53oie54g.pdf

H. Sakamoto

Papers

Superelasticity effects and stress-induced martensitic transformations in CuAlNi alloys

Successive stress-induced martensitic transformations and associated transformation pseudoelasticity in Cu-Al-Ni alloys

The Fracture of Cu–Al–Ni Shape Memory Alloy

Effect of Heat Treatments on Thermally Formed Martensite Phases in Monocrystalline Cu–Al–Ni Shape Memory Alloy

Fatigue and Fracture Characteristics of Polycrystalline Cu–Al–Ni Shape Memory Alloys