Orientational dependence of shape memory effects and superelasticity in CoNiGa, NiMnGa, CoNiAl, FeNiCoTi, and TiNi single crystals

Abstract

The dependence of deforming stresses, shape memory effect (SME), and superelasticity (SE) on the orientation of the single crystal axis, test temperature, and disperse particle size is examined for CoNiGa, NiMnGa, CoNiAl, FeNiCoTi, and TiNi single crystals. The orientational dependence of SME, SE, and temperature interval of the development of martensitic transformations (MT) under loading and SE is established. The influence of disperse particles on magnitudes of SME, SE, and mechanical hysteresis is discussed.

Tension - Compression Asymmetry in Co₄₉Ni₂₁Ga₃₀ High-Temperature Shape Memory Alloy Single Crystals

“…Many of the properties of CoNiGa HTSMAs such as structural and phase transformation characteristics [11,12] and fundamental shape memory and pseudoelastic behavior (i.e. transformation strains, stress and thermal hysteresis and cyclic stabilities as functions of temperature and stress) [13][14][15][16][17] have been thoroughly examined.…”

High-temperature superelasticity in CoNiGa, CoNiAl, NiFeGa, and TiNi monocrystals

“…In alloys which experience thermoelastic martensitic transformations (MTs) on cooling/heating and under load, the shape memory effect (SME) and superelasticity (SE) are observed [1][2][3][4][5][6][7][8]. Superelasticity is related to reversible MTs which develop under load, and it is usually observed at temperatures T > A f (M s , M f and А s , А f are the temperatures at the start and at the finish of direct and reverse MT, respectively).…”

“…It has been shown that the crystal orientation affects, first, α 1 whose minimum values are observed for [001] crystals and increase two times in going to [011] crystals(Table 2); second, the temperature and stress at which the transition from the first to the second stage takes place (see Figs 8. and 9); third, the temperature M d and σ 0.1 (M d ) (for [001] crystals the maximum M d ≈ 745 K is attained at the minimum stress σ 0.1 (M d ) = 380 MPa, whereas for [011] crystals M d = 685 K, σ 0.1 (M d ) = 930 MPa), and, fourth, the SE temperature range ΔT SE and the temperature Т 2 at which SE disappears.…”

Research Progress of Effect of Heat Treatment on Microstructure, Phase Transformation Behaviors and Memory Properties in Ti-Ni Based Shape Memory Alloys

“…The lower the aging temperature and the shorter the time, the better the alloy can obtain superelasticity. Chumlyakov et al [47] found that the stress-induced martensite transformation critical stress of Ti-Ni based SMAs depends on As temperature and grain orientation. The higher of As, the more favorable the orientation of the parent phase grains, and the lower the critical stress.…”