The effect of precipitates on the superelastic response of [1 0 0] oriented FeMnAlNi single crystals under compression

Abstract

a b s t r a c tFeMnAlNi shape memory alloys were recently discovered to have a small temperature dependence of the superelastic critical stress in a large superelastic temperature window from À196°C to 240°C. In this work, we investigated the effect of B2 nanoprecipitates on the superelastic characteristics of [1 0 0] oriented Fe 43.5 Mn 34 Al 15 Ni 7.5 single crystals under compression, and found that the size, volume fraction and composition of precipitates strongly influence the transformation temperature, superelastic strain, critical stress for stress-induced martensitic transformation and stress hysteresis of the single crystals. The single crystals aged at 200°C for 3 h show 7.2% superelastic strain with the precipitate size of about 6-10 nm. Longer aging times or higher aging temperature reduces superelastic recovery due to the coarsening of the precipitates.

Electron beam welding of Fe–Mn–Al–Ni shape memory alloy: Microstructure evolution and shape memory response

“…15 min at 200 ○ C, already led to the formation of a large fraction of β-phase particles. 5 However, the inherent processing conditions leading to the evolution of β-phase particles imposed by EB welding need to be addressed in more detail in future studies. After solution annealing and water quenching (from 1225 ○ C to 80 ○ C according to Ref.…”

“…high transformation strains and high bearable stresses in both pseudoelastic and actuation experiments. [4][5][6][10][11][12][13][14][15] However, most Fe-based SMAs suffer rapid cyclic functional degradation, currently hindering industrial utilization. 10,15 In single crystalline material, the microstructural mechanisms for cyclic degradation are often related to dislocation formation and concomitant pinning of phase boundaries.…”

“…This however remains the major roadblock towards a widespread industrial application of Ni-Ti SMAs. [1][2][3][4][5][6] Therefore, alternative shape memory materials like Cu-based 7,8 and Fe-based [4][5][6]9,10 SMAs received a lot of attention due to distinctly lower processing costs compared to conventional Ni-Ti SMAs. Fe-based SMAs are of highest relevance, due to the fact, that alloying elements are cheap and processing routes from steel industry are supposed to be well suited for manufacturing of these alloys.…”

Cyclic degradation in bamboo-like Fe–Mn–Al–Ni shape memory alloys — The role of grain orientation

“…It is well known that pseudoelastic performance in iron-based SMAs is strongly related to its anisotropic behavior [18][19][20][21][22]. In account of this, two bamboo-like samples with selected grain orientations, i.e.…”

Microstructure and Mechanical Properties in B-Doped Fe-31.9Ni-9.6Co-4.7Ti Alloys

“…Recently, a number of research groups have reported three different kinds of ferrous SMAs, Fe-Ni-Co-Al-based alloys (from fcc to bct) [9][10][11][12][13][14][15][16][17][18][19][20], Fe-Mn-Ga alloy (from L2 1 to D0 22 ) [21,22], and Fe-Mn-Al-Ni alloy (from bcc to nano-twinned fcc) [23][24][25][26][27][28], showing thermoelastic transformation. In case of the Fe-Ni-Co-Al-based and Fe-MnAl-Ni alloys, strengthening of the parent phase resulting from fine and coherent precipitates of the c 0 phase with the L1 2 structure and the b phase with the B2 structure by aging heat treatment are important to realize thermoelastic transformation and SE properties, respectively.…”