Thermal Synthesis of Nanocrystalline (Co<SUB>x</SUB>Ni<SUB>1-x</SUB>)<SUB>y</SUB>Fe<SUB>1-y</SUB> KOVAR Alloy through Gaseous Reduction of Mixed Oxides

Abstract

KOVAR is a very interesting and widely applied Fe-Ni-Co alloy. Nanocrystalline KOVAR alloy is successfully synthesized in the present investigation. The effect of hydrogen reduction on composition, microstructure and magnetic properties of produced Fe-Ni-Co alloy is investigated. A molar ratio of (99.9%) nickel oxide, cobalt oxide and ferric oxide for synthesis of 29% Ni-17% Co-Fe (KOVAR) alloy were thoroughly mixed and compressed into compacts. The dried compacts were reduced partially and completely at 500, 600, 700 and 800 C in a constant flowing hydrogen gas atmosphere (100% H 2 ). The course of reduction was followed up using the thermogravimetric technique to study the reduction behavior and kinetics reaction mechanism. The initial dried powder and the various reduction products were characterized by XRD, VSM, FE-SEM, EDX and reflected light microscope. At the higher reaction temperature (700-800 C) complete reduction was achieved with synthesis of nanocrystalline (13.9 nm) Fe-Ni-Co alloy. The activation energy values were calculated from the Arrhenius equation, and the approved mathematical formulations for the gas solid reaction were applied. It was found that the initial and final reduction stages are controlled by the combined gaseous diffusion and interfacial chemical reaction mechanisms.

Impact of Tm3+ and Tb3+ Rare Earth Cations Substitution on the Structure and Magnetic Parameters of Co-Ni Nanospinel Ferrite

“…In addition, it is well known that both Co-and Ni are inverse spinels, that exhibit homogeneous distribution in the A and B lattice sites; thus, their magnetic features are attributed to antiferromagnetic coupling amongst the tetrahedral and octahedral sublattices [27,28]. Furthermore, nickel substituted cobalt ferrites demonstrate good chemical stability and thus found applications as a binder and as magnetic filler in electromagnetic shielding nanocomposites [29][30][31]. Moreover, it is generally anticipated that rare-earth substituted spinel ferrites, in many cases, would show a superior electric and magnetic character when compared with the pristine spinel counterpart [32].…”

A numerical study of multi filament formation in metal-ion based CBRAM

“…2 Alloys made of Fe, Co and Ni have been reported to exhibit higher saturation induction and lower coercive field than the binary magnetic alloys. [1][2][3][4][5][6][7][8] Ni-Fe-Co alloys are being used as ideal magnetic materials in many templated magnetic structures and micro electro mechanical (MEMS) devices. 7 Also thin film of this alloy is used in magnetic/non-magnetic multilayer structures to produce effective giant magneto resistive devices.…”

“…[1][2][3][4][5][6][7][8] Ni-Fe-Co alloys are being used as ideal magnetic materials in many templated magnetic structures and micro electro mechanical (MEMS) devices. 7 Also thin film of this alloy is used in magnetic/non-magnetic multilayer structures to produce effective giant magneto resistive devices. [8][9][10][11] An alloy of Ni-Fe-Co with compositions Ni-50%, Fe-35% and Co-15% is being developed at IGCAR as a temperature dependent magnetic switch in liquid sodium cooled reactors.…”

Atomic scale understanding of magnetic properties in Ni50Fe35Co15

“…2 Alloys made of Fe, Co and Ni have been reported to exhibit higher saturation induction and lower coercive field than the binary magnetic alloys. [1][2][3][4][5][6][7][8] Ni-Fe-Co alloys are being used as ideal magnetic materials in many templated magnetic structures and micro electro mechanical (MEMS) devices. 7 Also thin film of this alloy is used in magnetic/non-magnetic multilayer structures to produce effective giant magneto resistive devices.…”

“…[1][2][3][4][5][6][7][8] Ni-Fe-Co alloys are being used as ideal magnetic materials in many templated magnetic structures and micro electro mechanical (MEMS) devices. 7 Also thin film of this alloy is used in magnetic/non-magnetic multilayer structures to produce effective giant magneto resistive devices. [8][9][10][11] An alloy of Ni-Fe-Co with compositions Ni-50%, Fe-35% and Co-15% is being developed at IGCAR as a temperature dependent magnetic switch in liquid sodium cooled reactors.…”