Characterization of the Fe-Co-1.5V soft ferromagnetic alloy processed by Laser Engineered Net Shaping (LENS)

Kustas, Andrew B.; Susan, Donald Francis; Johnson, Kyle L.; Whetten, Shaun R; Rodriguez, Mark A.; Dagel, Daryl; Michael, Joseph R.; Keicher, David M; Argibay, Nicolas

doi:10.1016/j.addma.2018.02.006

Cited by 46 publications

(31 citation statements)

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“…Different phenomena can cause abnormal grain growth, one being grain boundary pinning caused by the presence of second phase particles (Holm et al, 2015). Bimodal grain size distribution was also observed in heat-treated Fe-Co-V sample produced by additive manufacturing process previously (Kustas et al, 2018), where second phase particle pinning was named as a likely cause. The temperature of the normalizing heat treatment is high enough to relieve the internal stresses but possibly not high enough for full homogenization to take place.…”

Section: Microstructurementioning

confidence: 86%

“…The are some publications on the research of magnetic materials produced via additive methods other than L-PBF (Conteri et al, 2017;Li et al, 2017;Mikler et al, 2017aMikler et al, , 2017bSung and Rudowicz, 2003), but for the Fe-Co-V alloy, the amount of published research is very limited. Kustas et al (2018) produced ring-shaped samples for material characterization from commercial gas atomized Fe-Co-1.5V powder using laser engineered net shaping (LENS) technology. The printed and annealed material exhibited harder magnetic properties compared to an annealed wrought material, mainly because of the presence of heterogeneous bimodal grain size.…”

Section: Introductionmentioning

confidence: 99%

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Properties of soft magnetic Fe-Co-V alloy produced by laser powder bed fusion

Riipinen

Metsä-Kortelainen

Lindroos

et al. 2019

RPJ

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Purpose The purpose of this paper is to report on the developments in manufacturing soft magnetic materials using laser powder bed fusion (L-PBF). Design/methodology/approach Ternary soft magnetic Fe-49Co-2V powder was produced by gas atomization and used in an L-PBF machine to produce samples for material characterization. The L-PBF process parameters were optimized for the material, using a design of experiments approach. The printed samples were exposed to different heat treatment cycles to improve the magnetic properties. The magnetic properties were measured with quasi-static direct current and alternating current measurements at different frequencies and magnetic flux densities. The mechanical properties were characterized with tensile tests. Electrical resistivity of the material was measured. Findings The optimized L-PBF process parameters resulted in very low porosity. The magnetic properties improved greatly after the heat treatments because of changes in microstructure. Based on the quasi-static DC measurement results, one of the heat treatment cycles led to magnetic saturation, permeability and coercivity values comparable to a commercial Fe-Co-V alloy. The other heat treatments resulted in abnormal grain growth and poor magnetic performance. The AC measurement results showed that the magnetic losses were relatively high in the samples owing to formation of eddy currents. Research limitations/implications The influence of L-PBF process parameters on the microstructure was not investigated; hence, understanding the relationship between process parameters, heat treatments and magnetic properties would require more research. Originality/value The relationship between microstructure, chemical composition, heat treatments, resistivity and magnetic/mechanical properties of L-PBF processed Fe-Co-V alloy has not been reported previously.

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Section: Microstructurementioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Properties of soft magnetic Fe-Co-V alloy produced by laser powder bed fusion

Riipinen

Metsä-Kortelainen

Lindroos

et al. 2019

RPJ

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“…3D printing of the CoCrFeMnNi alloy powder was performed using an open architecture Laser Engineered Net Shaping (LENS) system that utilized a 2 kW fiber laser emitting at 1064 nm wavelength. The laser was mounted to the spindle of a Tormach PCNC 770 milling machine platform placed inside a glove box 68 . During processing, an inert atmosphere was maintained, with <50ppm O 2 and <10ppm H 2 O, by continuously flowing Ar gas.…”

Section: Methodsmentioning

confidence: 99%

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys

Jones

Nation

Wellington-Johnson

et al. 2020

Sci Rep

Self Cite

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We present evidence of inverse Hall-petch behavior for a single-phase high entropy alloy (cocrfeMnni) in ultra-high vacuum and show that it is associated with low friction coefficients (~0.3). Grain size measurements by STEM validate a recently proposed dynamic amorphization model that accurately predicts grain size-dependent shear strength in the inverse Hall-Petch regime. Wear rates in the initially soft (coarse grained) material were shown to be remarkably low (~10-6 mm 3 /n-m), the lowest for any HEA tested in an inert environment where oxidation and the formation of mixed metal-oxide films is mitigated. the combined high wear resistance and low friction are linked to the formation of an ultra-nanocrystalline near-surface layer. The dynamic amorphization model was also used to predict an average high angle grain boundary energy (0.87 J/m 2). this value was used to explain cavitationinduced nanoporosity found in the highly deformed surface layer, a phenomenon that has been linked to superplasticity. Since their discovery in 2004 1,2 , high entropy alloys (HEAs) have been extensively investigated and shown to exhibit remarkable thermomechanical properties 3,4. Studies of grain-size dependent mechanical behavior are limited 5,6 , however, especially in the regime of ultra-nanocrystalline grain size where softening (i.e. inverse Hall-Petch behavior) occurs. Recent work has also shown that these alloys are ideally suited for processing using laser-based additive manufacturing techniques 7-9 , as they exhibit high phase stability and derive much of their strength from thermal history-insensitive mechanisms like solution strengthening 10. While recent publications have presented experimental evidence of low friction or high wear resistance (but typically not both) with HEAs 11-25 , they were performed in environments where oxidation and the formation of mixed metal-oxide surface films was prevalent. These phenomena can greatly impact strength and deformation/wear resistance. We show that in an ultra-high vacuum (UHV) environment, i.e., in the absence of chemically reactive species, an additively manufactured initially coarse grained (soft), single-phase HEA exhibited a tendency toward low friction coefficients (i.e., low shear strength) and some of the lowest wear rates currently reported for these materials. The low friction and wear are attributed to a propensity for extreme grain refinement under sliding contact. Specifically, we present evidence of that this high strain rate shear leads to dynamic amorphization and inverse Hall-Petch behavior in the surface layer. In the present context of sliding contacts, dynamic amorphization refers to the continuous shear-induced generation of a structurally amorphous layer that accommodates deformation 26. This is in competition with stress-and temperature-driven grain growth and recrystallization, all of which reestablish crystallinity and order in the shear layer. The shear layer must be amorphized again in subsequent contact passes, thus we refer to this process as dynam...

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“…Specific work in intermetallics has been focused on materials such as titanium aluminides for high temperature strength, oxidation resistance, and creep resistance in the aerospace industry [1][2][3][4], or nickel titanium intermetallics for shape memory, damping, and biocompatibility for implants in the medical industry [5][6][7][8][9]. Only a few publications have investigated the potential for the selective laser melting (SLM) of magnetic intermetallics [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Grain Size Effects in Selective Laser Melted Fe-Co-2V

Everhart

Newkirk

2019

Applied Sciences

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The material science of additive manufacturing (AM) has become a significant topic due to the unique way in which the material and geometry are created simultaneously. Major areas of research within inorganic materials include traditional structural materials, shape memory alloys, amorphous materials, and some new work in intermetallics. The unique thermal profiles created during selective laser melting (SLM) may provide new opportunities for processing intermetallics to improve mechanical and magnetic performance. A parameter set for the production of Fe-Co-2V material with additive manufacturing is developed and efforts are made to compare the traditional wrought alloy to the AM version of the same chemistry. Evaluation includes magnetic properties, composition, and phase as a function of thermal history, as well as mechanical performance. Results show significant similarities in microstructure between AM and wrought materials, as well as mechanical and magnetic performance. Property trends are evaluated as a function of grain size and show effects similar to the Hall–Petch strengthening observed in wrought material, though with some underprediction of the strength. Magnetic properties qualitatively follow the expected trends but demonstrate some deviation from wrought material, which is still unexplained.

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Characterization of the Fe-Co-1.5V soft ferromagnetic alloy processed by Laser Engineered Net Shaping (LENS)

Cited by 46 publications

References 50 publications

Properties of soft magnetic Fe-Co-V alloy produced by laser powder bed fusion

Properties of soft magnetic Fe-Co-V alloy produced by laser powder bed fusion

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys

Grain Size Effects in Selective Laser Melted Fe-Co-2V

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