Strain glass state in Ni-rich Ni-Ti-Zr shape memory alloys

Abstract

[eng] This work reports the existence of the strain glass state in Ni-rich Ni-Ti-Zr shape memory alloys induced by the precursor stages of the H-phase precipitation, typical of this alloy system. The strain glass is detected from dynamic mechanical testing and microstructural observations by electron diffraction and Transmission Electron Microscopy (TEM). The elastic modulus measurements also suggest the elinvar effect in these alloys. The strain glass state of this material exhibits superelastic effect in compression with recoverable strain levels over 4% and very little temperature dependence of the stress-strain curves over a temperature range of 230 to 300 K.