Origin of an IsothermalR-Martensite Formation in Ni-rich Ti-Ni Solid Solution: Crystallization of Strain Glass

Abstract

We report that R martensite isothermally forms with time in a solution-treated Ti(48.7)Ni(51.3) single crystal. This abnormal formation originates from the growth of a short-range ordered R phase with time, i.e., the "crystallization" of strain glass. The established time-composition-temperature Ti-Ni diagram shows a time evolution of the R phase and composition-temperature phase diagram. The presence or absence of the R phase in this new diagram, as well as in other conditions (like doping Fe or aging), is explained in a unified framework of free-energy landscape. Our finding suggests a new mechanism for the isothermal martensite formation, which could be applied to other metal and ceramic martensitic systems to find new phases and novel properties.

Unusual strain glassy phase in Fe doped Ni2Mn1.5In0.5

“…It may be noted the compositions with x = 0.15 and x = 0.2 do not show any transition down to lowest measured temperature despite having sizable (> 10%) fraction of martensitic phase. Recently, crystallization of strain glass via a isothermal transformation has been reported in Ni rich NiTi alloys [13]. In order to check such a possibility of isothermal growth of martensitic phase in these alloys, DSC measurements were performed on x = 0.1 alloy using the same procedure as described in Ref.…”

Connecting the Simpler Structures to Topologically Close-Packed Phases

“…Phase transformations connecting vastly different crystal structures are ubiquitous in pure elements and multicomponent crystals and are exploited in shapememory [1][2][3][4][5][6], magnetocaloric [7,8] and precipitation strengthened alloys [9,10]. The structural pathways be- [12], which combines a macroscopic shape change with an internal atomic shuffle within the hcp unit cell.…”

Glass-ferroic composite caused by the crystallization of ferroic glass

“…From the results of Ti 48.7 Ni 51.3 and PLZT, it can be concluded that the crystallization transition of ferroic glasses produces the glass-ferroic. It originates from a time-dependent crystallization process, which can be understood in the context of a classical free-energy landscape containing multiple minima (basins) separated by local barriers [1, 20,21]. The associated microstructure evolution upon continuous cooling and heating was simulated by the phase field modeling [19].…”

“…4(a1)], will gradually trap in specific basins. Because of the low kinetic energy (k B T ), some local barriers caused by disorder (e.g., point defects [7,20,21] and nanosized precipitates [9]) cannot be overcome, thereby leading to "frozen" configurations (a glass state) [ Fig. 4(b1)].…”