Magnetic field-induced magnetostructural transition and huge tensile superelasticity in an oligocrystalline Ni–Cu–Co–Mn–In microwire

Abstract

Meta-magnetic shape-memory alloys combine ferroelastic order with ferromagnetic order and exhibit attractive multifunctional properties, but they are extremely brittle, showing hardly any tensile deformability, which impedes their practical application. Here, for the first time, an Ni–Cu–Co–Mn–In microwire has been developed that simultaneously exhibits a magnetic field-induced first-order meta-magnetic phase transition and huge tensile superelasticity. A temperature-dependent in situ synchrotron high-energy X-ray diffraction investigation reveals that the martensite of this Ni43.7Cu1.5Co5.1Mn36.7In13 microwire shows a monoclinic six-layered modulated structure and the austenite shows a cubic structure. This microwire exhibits an oligocrystalline structure with bamboo grains, which remarkably reduces the strain incompatibility during deformation and martensitic transformation. As a result, huge tensile superelasticity with a recoverable strain of 13% is achieved in the microwire. This huge tensile superelasticity is in agreement with our theoretical calculations based on the crystal structure and lattice correspondence of austenite and martensite and the crystallographic orientation of the grains. Owing to the large magnetization difference between austenite and martensite, a pronounced magnetic field-induced magnetostructural transition is achieved in the microwire, which could give rise to a variety of magnetically driven functional properties. For example, a large magnetocaloric effect with an isothermal entropy change of 12.7 J kg−1 K−1 (under 5 T) is obtained. The realization of magnetic-field- and tensile-stress-induced structural transformations in the microwire may pave the way for exploiting the multifunctional properties under the coupling of magnetic field and stress for applications in miniature multifunctional devices.

Multifunctional behaviors in meta-magnetic shape-memory microwires

“…90 A m 2 kg À1 . In particular, in the temperature range from 160 to 180 K, the reversible field-induced magnetostructural transformation can be induced by a magnetic field of 5 T. Based on this, Chen et al (2019) also demonstrated a large reversible inverse magnetocaloric effect in the microwires, where a large reversible isothermal entropy change ÁS M of 12.7 J kg À1 K -1 under a field change of 5 T was obtained.…”

“…A promising option is to employ oligocrystalline-structured microwires with bamboo-like grains, because strain incompatibility during deformation and martensitic transformation can be greatly reduced (Ueland et al, 2012). In this issue of IUCrJ, Chen et al (2019) successfully prepared an Ni 43.7 Cu 1.5 Co 5.1 Mn 36.7 In 13 microwire using the Taylor-Ulitovsky method (Chiriac & Ó vá ri, 1996), with the integration of pronounced mechanical and magnetic properties demonstrated by the tensile superelasticity and the magnetocaloric effect, respectively. The realization of multifunctionality in microwires provides a solid foundation for exploiting potential intelligent applications in miniaturized devices under multifield coupling.…”

“…In the recent work of Chen et al (2019), oligocrystallinestructured Ni 43.7 Cu 1.5 Co 5.1 Mn 36.7 In 13 microwires with a diameter of 100~200 mm were successfully fabricated using the Taylor-Ulitovsky method (Chiriac & Ó vá ri, 1996), a costeffective way involving quenching and drawing to prepare the microwires. In the microwires, Co and Cu were added to Ni-Mn-In in order to improve the ferromagnetism of austenite and ductility, respectively.…”

“…The great improvement of mechanical properties in Ni-Mn-X meta-magnetic shape-memory microwires achieved by Chen et al (2019) represents a significant advance towards potential small scale applications in actuators, sensors and magnetic refrigeration. Above all, the combination of stress and magnetic-field-induced magnetostructural transformation in microwires could provide the ideal prototype materials to simultaneously achieve various caloric effects by utilizing the transformation latent heat, e.g.…”

External-Field-Induced Phase Transformation and Associated Properties in a Ni50Mn34Fe3In13 Metamagnetic Shape Memory Wire

“…The Taylor-Ulitovsky method, which involves rapid solidification and drawing, is prone to produce microwires with an oligocrystalline structure. This structure reduces the incompatibility between different grains and thus effectively enhances the mechanical properties of Ni-Mn-based MMSMAs [23,24]. Although scattered attempts have been made to investigate the external-fieldinduced transformation of Ni-Mn-based MMSMA microwires that were prepared using this method, the reported microwires with a magnetic-field-induced transformation exhibit a limited recoverable strain of superelasticity and those with a large recoverable strain barely display magnetic-field-induced transformation.…”