Strain Glasses

Abstract

Since its discovery in 2005 in a Ni-rich Ti-Ni alloy, strain glass has drawn much attention in martensite/ferroelastic community and has been reported to be a rather general phenomenon in martensitic/ferroelastic systems. In this chapter we present a review of strain glass, including a brief history, its physical origin, its generic phase diagram, followed by presenting strain glasses in various martensitic/ferroelastic systems induced by 0D defects (point defects), 1D defects (dislocations), and 3D defects (nano-precipitates), respectively. The material systems include Ti-Ni-based systems, Ti-Pd-based systems, Ti-based alloys, ferromagnetic shape memory alloys and ceramics. We further show that strain glass can result in technologically important properties such as the “Gum metal” properties, high damping, and giant magnetostriction at small field, thus making strain glass a promising candidate for novel structural/functional materials. Finally, a “ferroic glass” concept (the glass form of ferroic materials) is introduced by combining three physically parallel glasses: strain glass, relaxor ferroelectrics, and cluster spin glass. It is expected that ferroic glasses and generic ferroic glasses may yield unique mechanical, electrical, magnetic properties, and thus may lead to a new class of structural/functional materials.