Fatigue life and fracture mechanics of unconstrained Ni–Mn–Ga single crystals in a rotating magnetic field

Lawrence, Theodore Bryson; Lindquist, Paul; Ullakko, K.; Müllner, Peter

doi:10.1016/j.msea.2015.12.045

Cited by 13 publications

(3 citation statements)

References 30 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the first observation of the magnetic field induced strain in Ni2MnGa by Ullakko [1], the ferromagnetic shape memory alloys (FSMAs) have attracted a great attention as a kinds of intelligent material for actuator and sensor. In past two decades, based on twin martensite variants remigration, numerous FSMAs, such as Ni-Mn-Ga [2][3][4], Co-Ni-Al [5,6], Mn-Ni-Sn [7], and Ni-Fe-Ga [8,9], achieved 8-10% giant stain. However, the actuator and sensor made of FSMAs did not get a wide range of applications due to their low phase transition temperature and poor mechanical properties [10].…”

Section: Introductionmentioning

confidence: 99%

Martensite Transformation and Mechanical Properties of Polycrystalline Co-Ni-Al Alloys with Gd Doping

Liu

Shuai

et al. 2018

Metals

View full text Add to dashboard Cite

In order to improve the mechanical properties and phase transition temperature, the influence of Gd doping on the microstructure, phase transition temperature and mechanical properties of Co35Ni32Al33 alloy was investigated. The results show that the γ+β phase was observed in the microstructure of the sample with less Gd doping and the γ phase+martensite was found with more Gd content. The phase transition temperature apparently increases with Gd doping and the phase transition temperature goes over room temperature when the Gd is 3 at.% or more. With increasing Gd doping, more γ phase appears in the sample which results in decrease in hardness. The compressive strength decreases from 2274 to 1630 MPa and the ductility increase from 4.2 to 12.9% with increasing Gd content.

show abstract

Section: Introductionmentioning

confidence: 99%

Martensite Transformation and Mechanical Properties of Polycrystalline Co-Ni-Al Alloys with Gd Doping

Liu

Shuai

et al. 2018

Metals

View full text Add to dashboard Cite

show abstract

“…In MSM-polymer hybrids the MSM particles are embedded in the polymer matrix and bonded to the matrix, the strength depending on the adhesion properties of the polymer with MSM. It has been reported that the brittleness of Ni-Mn-Ga may cause cracks into the material [12]. In such a case the polymer would hold the structure together and a hybrid component could be still usable despite of the cracks.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Shape Memory - Polymer Hybrids

Aaltio

Nilsén

Lehtonen

et al. 2016

MSF

View full text Add to dashboard Cite

Martensitic Ni-Mn-Ga based alloys are known for the Magnetic Shape Memory (MSM) effect, which upon application of an external magnetic field can generate a strain up to 12 % depending on the microstructure of the martensite. The MSM effect occurs by rearrangement of the martensite variants, which is most advantageous in single crystals. Single crystals are, however, rather tedious to produce and there has been attempts to achieve MSM effect in polycrystals. However, in polycrystals the magnetic field induced shape change remains low as compared to single crystals. As an alternative to the former, hybrid MSM materials offer several advantages. When compared to single crystals, hybrids have extended freedom of shaping, lower raw material price, relatively large MSM strain and easier manufacturability. Embedding MSM particles into a suitable polymer matrix results in actuation function or good vibration damping performance. In the present study we report on the mechanical, structural and magnetic properties of MSM polymer hybrids, which are prepared by mixing gas-atomized Ni-Mn-Ga MSM powder into epoxy matrix and aligning the magnetic particles in a magnetic field.

show abstract

“…In (b) the sample has twinned in response to the field, now taking a different field pattern, the field lines slightly deflected by twin boundaries [89]. Reprinted from Scripta Materialia, 77 (1) was attached to the sample holder (2) by double-sided tape. The tube (4) coupled to the HD camera (5), which recorded the reflection of sample through a mirror (3) while these components were rotated in the magnetic field (6) by a sequence-controlled motor.…”

mentioning

confidence: 99%

Material Design, Processing, and Engineering Requirements for Magnetic Shape Memory Devices

Armstrong¹

View full text Add to dashboard Cite

For magnetic shape memory (MSM) alloys, a magnetic field stimulates a shape change. We use the shape change to build devices such as micro-actuators, sensors, and microfluidic pumps. Currently, (as a novel technology,) devices suffer from some material and magnetic driver shortcomings. Here we address the issues related to operating temperature, repeatability, failure, and magnetic driver development. To increase the operating temperature of the MSM material, we alloyed Fe and Cu to Ni-Mn-Ga. We showed that the element-specific contribution to the valence electron density as parameter systematically determines the effect of each element on the variation of the martensite transformation temperature of the 10M phase. To stabilize the material, we developed a micro-shotpeening process that adds stresses to the material surface, thereby inducing a fine twin microstructure. The treatment allowed nearly full magnetic-field-induced strain, and extended fatigue life of the material from only one thousand cycles in the electropolished state to more than one million cycles in the peened state. We measured the effect of the peening process on material actuation when in MSM pump configuration. In the polished state, the deformation was stochastic, with a sharp-featured, faceted shrinkage. In the treated state, the deformation was smooth and repeatably swept along the surface akin to a wave. To actuate the MSM micropump without electromotor, we developed a linear electromagnetic actuation device and evaluated its effectiveness in the switching mechanism of the material. By compressing the magnetic field between opposing coils, we generated a strong magnetic field, which caused a localized region to switch at selected poles. In the next iteration of the drive, we inserted the MSM sample between two linear pole arrangements of high pitch density to approximate a moving vertical field. The incremental stepping of the vertical field between poles caused translation of the switched region. The results of this dissertation demonstrate the suitability of MSM alloys for high-precision, persistent, and reliable actuators such as micropumps.

show abstract

Fatigue life and fracture mechanics of unconstrained Ni–Mn–Ga single crystals in a rotating magnetic field

Cited by 13 publications

References 30 publications

Martensite Transformation and Mechanical Properties of Polycrystalline Co-Ni-Al Alloys with Gd Doping

Martensite Transformation and Mechanical Properties of Polycrystalline Co-Ni-Al Alloys with Gd Doping

Magnetic Shape Memory - Polymer Hybrids

Material Design, Processing, and Engineering Requirements for Magnetic Shape Memory Devices

Contact Info

Product

Resources

About