Thermal expansions and mechanical properties of electrodeposited Fe–Ni alloys in the Invar composition range

Nagayama, Tomio; Yamamoto, Takayo; Nakamura, Toshihiro

doi:10.1016/j.electacta.2016.04.089

Cited by 78 publications

(47 citation statements)

References 19 publications

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“…In this work malonic acid (MA) was used, as described in patent 38 and scientific literature, 39 as a complexing agent for Fe +3 ions in the electrodeposition of CoFe and NiFe alloys. MA forms a stable complexes with Fe +3 ions (FeMA + ) that has a stability constants (logβ 101 = 7.5) several orders of magnitude higher than complexes with Fe +2 ions (FeMA),i.e.…”

Section: Resultsmentioning

confidence: 99%

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Ghemes

Dragos-Pinzaru

Chiriac

et al. 2016

J. Electrochem. Soc.

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Among all transition metals magnetic alloys, Co 35 Fe 65 possesses the highest saturation magnetization B S = 2.45 T at room temperature given by the so-called "Slater-Pauling limit". For controlled electrodeposition of Co 35 Fe 65 nanowire arrays the following parameters were found to be optimal: electrolyte solution with 1-2 mM malonic acid (MA), ionic ratio Fe +2 /Co +2 = 2.0, growth rate, and pulsed potential deposition with time-on (2.5 s) at the potential of −1.15 V/SCE and time-off (1.0 s) at −0.70 V/SCE. These arrays were deposited inside anodic aluminum oxide (AAO) templates that contained columnar nanopores with diameters either 35 or 200 nm. Cyclic voltammetry was used in solution with and without MA and reaction mechanism was proposed to explain the critical role of MA in electrodeposition of CoFe alloys. In addition to uniform deposition of stechiometric Co 35 Fe 65 alloys, a selectivity ratio, (SR) ∼1.0, were achieved, which means that the atomic ratio of Fe/Co in the nanowire matched the molar ratio of Fe +2 /Co +2 in the electrolyte. The magnetic behavior of the subsequent 2.45 T Co 35 Fe 65 nanowire arrays showed that the shape and magnetostatic anisotropies dominated the effective anisotropy, and the impact of magnetocrystalline and magnetelastic anisotropies field was very small. 1 The highest saturation magnetization of all transition-metal (TM) alloys at room temperature shows Co 36 Fe 65 alloy with respective saturation magnetization of B s = 2.45 T, which is commonly referred to us as the "Slater-Pauling limit".2 Thin films of these alloys, obtained either by electrochemical deposition (ED) or called sputter deposition, are currently used in high areal recording density (HRD) heads including longitudinal (LMR), perpendicular (PMR), and heat assisted (HAMR) magnetic recording. In fact, about 15 years ago Seagate Technologies was first in the recording head industry to introduce 2.4 T CoFe as the longitudinal writer pole material-which was fabricated by electrodeposition. 3 The advantages of electrochemical vs. sputtering deposition include reduced process content, reduced variance and reduced cost. Importantly, controlled electrodeposition is possible even into high aspect ratio of templates including anodized aluminum oxide-AAO, diblock copolymers-DBC, carbonate membranes, and porous silicone. Porous AAO templates are particularly attractive since the pore diameters can be 10-300 nm with pore densities in the range of 10 9 to 10 11 cm −2 . 4 Ferromagnetic nanowire arrays have been used as a miniaturized devices in electronics and optics. 5 In addition, such nanowires have a promising biomagnetic applications like biosensing, cell separation, MRI contrast agents and magnetic hyperthermia. [6][7][8][9][10] Most biomagnetic studies have been limited to nanometer iron-oxide based nanoparticles for MRI imaging and magnetic hyperthermia.6 However, the low saturation magnetization of the bulk iron-oxides (e.g. B s ∼0.5 T for Fe 2 O 3 11 ) prevents them from becoming highly efficient in hypertherm...

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Section: Resultsmentioning

confidence: 99%

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Ghemes

Dragos-Pinzaru

Chiriac

et al. 2016

J. Electrochem. Soc.

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“…It is noted that the anomalous co-deposition behavior of Fe and Ni ions during the electrodeposition of Fe-Ni alloys appears significant with increasing Fe contents. As a result, the α phase would grow into a columnar type of large-sized grains rather than nanocrystals as observed in the materials of Nagayama et al [13], see also Figure 3. The development of the columnar structure in the electroformed Fe-Ni alloys results in through-thickness inhomogeneity of the alloy composition.…”

Section: Resultsmentioning

confidence: 90%

“…Thus, the presence of a small amount of the γ″ phase is responsible for the CTEs of the samples annealed at 653 K (380 °C) for 3 min decreasing only slightly compared with the CTE of the as-deposited material. Nagayama et al [13] also reported a substantial decrease of the CTEs due to the BCC → FCC phase transition in electroformed Fe-Ni Figure 4. Example of the atom configurations for the Fe-36 wt % Ni composition.…”

Section: Resultsmentioning

confidence: 99%

The Gain of Low Thermal Expansivity via Phase Transition in Electroformed Invar

Park

Kim

2018

Coatings

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Abstract:In the organic light-emitting diode display industry, Invar exhibits anomalously low thermal expansivity and is, therefore, used as a material for fine metal masks, which are necessary components for the evaporation process of diode materials. We present an electroforming method for fabricating Fe-Ni alloys with a coefficient of thermal expansion lower than that of conventional Invar. The principle of controlling the thermal expansivity of electroformed Fe-Ni alloys is clarified in terms of the behavior of the phases constituting them. The cause of the Invar anomalies, which has not yet been fully elucidated, is explained by combining the Weiss model based on the electron configurations of Fe atoms and a model that we propose based on atom configurations.

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“…For the temperature range between 300 °C and 400 °C, the Fe-Ni alloy electroformed metal mask had a negative CTE. This phenomenon was considered to be caused by an increase in the atomic packing density (contraction) because of a phase transformation from metastable body-centered cubic (bcc) phases to equilibrium face-centered cubic (fcc) phases [4,5,[7][8][9] and reduction of the defects (contraction) because of the recrystallization of the Fe-Ni alloy electroformed metal mask by heating [4,5,7]. Furthermore, for temperatures above 400 °C, a rapid increase in the length of the specimen was detected.…”

Section: Resultsmentioning

confidence: 99%

“…A process for producing crack-free invar Fe-36 mass% Ni alloy electrodeposits with lower CTEs than those of conventional Ni and Ni-Co alloys has been reported in previous studies [3][4][5]. Furthermore, coarse (the open area was 80 × 80 μm 2 ) and thick (approximately 80 μm thickness) Fe-Ni alloy masks with low CTEs have been fabricated via electroforming [6]; however, the sizes of the open areas and thickness of such metal masks are unsuitable for fabricating fine-pitch OLED displays.…”

Section: Introductionmentioning

confidence: 88%

37‐3: Low Thermal Expansion and Fine‐Pitch Metal Masks Fabricated via Invar Fe‐Ni Alloy Electroforming for Large Fine‐Pitch OLED Displays

Nagayama

Yamamoto

Nakamura

2017

Symp Digest of Tech Papers

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Fine-pitch metal masks with approximately 10 μm thick and fine rectangular open areas (10 × 30 μm 2 ) were fabricated via invar Fe-Ni alloy electroforming (KEEPNEX TM ). The coefficient of thermal expansion (CTE) of the mask annealed at 600 °C was approximately 3 ppm/°C, i.e., four times lower than that of conventional electroformed Ni and Ni-Co alloys. The proposed alloy masks are expected to be used in vapor deposition processes to produce large fine-pitch OLED displays.

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Thermal expansions and mechanical properties of electrodeposited Fe–Ni alloys in the Invar composition range

Cited by 78 publications

References 19 publications

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

The Gain of Low Thermal Expansivity via Phase Transition in Electroformed Invar

37‐3: Low Thermal Expansion and Fine‐Pitch Metal Masks Fabricated via Invar Fe‐Ni Alloy Electroforming for Large Fine‐Pitch OLED Displays

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Thermal expansions and mechanical properties of electrodeposited Fe–Ni alloys in the Invar composition range

Cited by 78 publications

References 19 publications

Controlled Electrodeposition and Magnetic Properties of Co35Fe65Nanowires with High Saturation Magnetization

Controlled Electrodeposition and Magnetic Properties of Co35Fe65Nanowires with High Saturation Magnetization

The Gain of Low Thermal Expansivity via Phase Transition in Electroformed Invar

37‐3: Low Thermal Expansion and Fine‐Pitch Metal Masks Fabricated via Invar Fe‐Ni Alloy Electroforming for Large Fine‐Pitch OLED Displays

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Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization