Stress-induced and thermoelastic properties of Ni–Fe–Al melt-spun ribbon

Abstract

Lattice parameters, elastic modulus, internal friction, superelasticity, and shape memory effect are studied in the vicinity of martensitic transformation (MT) exhibited by the Ni55Fe20Al25 melt-spun ribbon. In comparison to the melt-spun ribbons of other ferromagnetic shape memory alloys, Ni–Fe–Al ribbon has abnormally low elastic modulus, a record-breaking strength (>350 MPa), and large recoverable strain (up to 5%) due to both the superelastic and ordinary shape memory effects. The critical stress versus temperature phase diagram consists of two straight lines, indicating the formation of different stress-induced martensitic phases. The structural and thermodynamic results proved to be self-consistent.

Shape memory behavior of Ni-Fe-Ga and Ni-Mn-Sn ribbons

“…It is worth noting that, for the temperatures between M S and A F , the stresses required to induce the whole transition are, in practice, unachievable due to the enhanced brittleness of the studied material. The recoverable strain in the martensite phase (about 3%) is comparable to the Ni-Fe-Al ribbons [7]. In the austenite phase, increasing the temperature produces a reduction of the strain recovery (below 2%) but larger stresses can be applied.…”

“…5). Due to the smooth shape of V-H curves, we have defined the numerical values of the critical stress by a tangent method, i.e., at the cross points of the linearly extrapolated initial slope and the slope during transformation [7]. The data in Fig.…”

“…The melt-spinning is a frequently used cost effective way to produce SMAs in the form of the ribbons representing a ready material for the tensile applications, e.g., in solid state refrigeration. Recent studies of Ni-Fe-Al ribbons obtained by the meltspinning technique have shown an enhanced strength and considerable recoverable strain [7][8]. This technique apparently presents interesting fabrication advantages, as it makes unnecessary plastic deformation routes to machine the material with the appropriate geometries, and the high temperature thermal treatment step usually needed to obtain single-phase alloy with given functional properties [9].…”

Structural, Magnetic and Transport Properties of Ni-Fe-Al Alloys

“…Rectangular strips of dimensions 40 x 2.5 x 0.5 mm 3 and spheres of 3 mm diameter were spark-cut from the rods. The spark-cut samples were annealed at 520 °C for 16 days in a sealed quartz tube filled with 99.999% purity argon gas and subsequently quenched in ice water.…”

“…Recently, excellent thermo-mechanical properties such as abnormally low elastic modulus, record-breaking strength > 350 MPA and large recoverable strains (up to 5%) have been reported [3] in the MSR of sitedisordered Ni-Fe-Al alloys with B2 structure. These properties are far superior to those of other well-known FSMAs such as Ni-Mn-Ga, Ni-Fe-Ga, Co-Ni-Al, etc., [4 -6].…”