Fracture toughness evaluation of Ni2MnGa magnetic shape memory alloys by Vickers micro indentation

D’Silva, Glen J.; Goanță, Viorel; Ciocanel, Constantin

doi:10.1016/j.engfracmech.2021.107655

Cited by 5 publications

(7 citation statements)

References 27 publications

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“…Relevant scholars determined the crack type based on the c / a ratio ( c = half‐length of crack, a = half‐length of indentation diagonal). It is assumed that if c / a < 2.5, the crack type is the Palmqvist crack, and if c / a ≥ 2.5, it is half‐penny crack 25,26 . The combined data show that when the load was 19.6 and 49 N, the crack type was the Palmqvist crack.…”

Section: Resultsmentioning

confidence: 99%

Ultrafine‐grained β‐Sialon fabricated by two‐stage sintering and study on diffusion toughening of Ti–22Al–25Nb

Cui

Guo

et al. 2023

Int J Applied Ceramic Tech

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The ultrafine-grained β-Sialon ceramics were fabricated by spark plasma sintering at different temperatures with inorganic Al 2 O 3 -Y 2 O 3 and Ti-22Al-25Nb intermetallic powder as composite additives. The research showed that β-Sialon ceramics achieve two-stage sintering densification. Al 2 O 3 -Y 2 O 3 inorganic additives promoted the synthesis and densification of β-Sialon ceramics at 1125-1215 • C. Ti-22Al-25Nb intermetallic powder diffused Ti and Nb elements at 1240-1425 • C, thereby improving the fracture toughness of β-Sialon ceramics. The maximum fracture toughness (∼9.69 MPa m 1/2 ) under 19.6 N was obtained for β-Sialon ceramics sintered at 1600 • C.

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Section: Resultsmentioning

confidence: 99%

Ultrafine‐grained β‐Sialon fabricated by two‐stage sintering and study on diffusion toughening of Ti–22Al–25Nb

Cui

Guo

et al. 2023

Int J Applied Ceramic Tech

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“…This can be seen in the hysteresis of the stress vs. strain plot from figure 9. Although the Ni 2 MnGa sample is a single crystal, defects may still be present in the single crystal leading to pinning sites [28,29] causing additional energy dissipation during variant reorientation. To reduce the energy dissipation and improve the efficiency of MSMA power harvesters, one may aim to either grow defect free single crystals or to develop a training process for the material that would further reduce the energy dissipation associated with variant reorientation/twin boundary motion.…”

Section: Recommendations and Conclusionmentioning

confidence: 99%

On the power and efficiency of Ni₂MnGa magnetic shape memory alloy power harvesters

D’Silva¹,

Feigenbaum²,

Ciocanel³

2022

Smart Mater. Struct.

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The martensite variant reorientation in Ni2MnGa magnetic shape memory alloys (MSMAs) causes a change in their bulk magnetization, that can be harvested into useful voltage/power by means of a pick-up coil. The coil may be placed directly surrounding an MSMA element or to the side of the MSMA element wrapped around a magnetic core. This paper reports new power harvesting data generated with a bi-axial magnetic field and a surrounding coil and full strain field data for an MSMA subject to load similar to what is seen during power harvesting, then compares the performance of MSMA-based power harvesters with different designs to determine which give the best output. For this comparison, we provide a framework for evaluating the performance of MSMA-based power harvesters reported in the literature. This framework involves normalizing the results to the design characteristics of the respective harvesters, i.e. number of turns of the pickup coil, cross-sectional area of the pickup coil, frequency of excitation, and sample size, to allow for a direct comparison of power harvesters’ output. Results show that power harvesting with the bi-axial field and a surrounding coil does not generate as much power as previously thought. The strain maps reveal the potential for perpendicular twin boundaries that block each other’s motion limiting variant reorientation and correspondingly the harvester’s power output. The paper concludes that the largest change in magnetic flux density, which is the driver for power harvesting, occurs in the side coil setup with an optimized magnetic circuit and it recommends using this configuration for future MSMA-based power harvester designs for maximum power output.

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“…surfaces along which lattice points are shared between the twinned variants [5][6][7], separate the variants. During magnetic or mechanical loading, the martensite variant with a magnetic easy axis aligned with the external magnetic field or mechanical load can grow at the expense of the other variant resulting in reorientation of the microstructure, twin boundary nucleation/motion, macroscopic strain, and change in the material's magnetization [3,4,[8][9][10]. The large reorientation strain, up to 10% [11,12], and the fast deformation rate, up to 1 kHz [13][14][15], make Ni 2 MnGa MSMAs suitable for use in actuators, sensors, and power harvesting devices [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Strain field in Ni₂MnGa magnetic shape memory alloys with different twin densities under combined tensile and magnetic loading

D’Silva,

Feigenbaum,

Ciocanel

2023

Smart Mater. Struct.

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This study investigates the strain fields developed in two Ni2MnGa samples, with fine and coarse twin structures, respectively when loaded in tension and/or with a magnetic field. The strain fields have been recorded using the digital image correlation technique, which allowed for the observation of the strain field over the entire sample as it evolves with load. This allows for visual observation of the evolution of the sample’s twin microstructure. This investigation provides a more comprehensive insight into the localized and bulk material behavior than the traditional strain measurement techniques used in previous studies. The results show that the twin density, the uniformity of the magneto-mechanical loading along the sample, and the presence of pinning sites are all contributing to the profile of the tensile strain field. Particularly, the presence of pinning sites and the emergence of perpendicular twin boundaries along the sample inhibit full variant reorientation and recovery. Both samples showed no visible signs of damage or crack formation during tensile testing, and their magneto-mechanical response in tension and compression was found to be similar, but there is a clear tension/compression asymmetry.

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Fracture toughness evaluation of Ni2MnGa magnetic shape memory alloys by Vickers micro indentation

Cited by 5 publications

References 27 publications

Ultrafine‐grained β‐Sialon fabricated by two‐stage sintering and study on diffusion toughening of Ti–22Al–25Nb

Ultrafine‐grained β‐Sialon fabricated by two‐stage sintering and study on diffusion toughening of Ti–22Al–25Nb

On the power and efficiency of Ni₂MnGa magnetic shape memory alloy power harvesters

Strain field in Ni₂MnGa magnetic shape memory alloys with different twin densities under combined tensile and magnetic loading

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Fracture toughness evaluation of Ni2MnGa magnetic shape memory alloys by Vickers micro indentation

Cited by 5 publications

References 27 publications

Ultrafine‐grained β‐Sialon fabricated by two‐stage sintering and study on diffusion toughening of Ti–22Al–25Nb

Ultrafine‐grained β‐Sialon fabricated by two‐stage sintering and study on diffusion toughening of Ti–22Al–25Nb

On the power and efficiency of Ni2MnGa magnetic shape memory alloy power harvesters

Strain field in Ni2MnGa magnetic shape memory alloys with different twin densities under combined tensile and magnetic loading

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Product

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On the power and efficiency of Ni₂MnGa magnetic shape memory alloy power harvesters

Strain field in Ni₂MnGa magnetic shape memory alloys with different twin densities under combined tensile and magnetic loading