Kinetics of thermal devitrification of some titanium amorphous alloys

Šušić, M.V.

doi:10.1007/bf01086506

Cited by 12 publications

(2 citation statements)

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“…In recent years, a lot of new materials are obtained by sintering of powders. Metalic amorphous alloys with magnetic properties are especially widely applied [1][2][3][4][5][6][7][8]. Amorphous alloys are characterized by a metastable state and when heated, the process of structural relaxation takes place in them [9][10][11][12][13][14][15][16].…”

Section: ________________mentioning

confidence: 99%

The influence of structural changes on electrical and magnetic characteristics of amorphous powder of the nixmoy alloy

Ribić-Zelenović¹,

Rafailović²,

Spasojević³

et al. 2006

SCI SINTER

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Nickel and molybdenum alloy powder was electrodeposited on a titanium cathode from a NiSO4⋅7H2O and (NH4)6 Mo7O24⋅4H2O ammonium solution. The desired chemical composition, structure, size and shape of particles in the powder samples were achieved by an appropriate choice of electrolysis parameters (current density, composition and temperature of the solution, cathode material and electrolysis duration). Metal coatings form in the current density range 15 mA cm-2<j<30 mA cm-2. If the current density is greater than 40mA cm-2 then powders form. The chemical composition of powder samples depends on the current density of electrodeposition. The molybdenum content in the powder increases with the increase of current density (in the low current density range), while in the higher current density range the molybdenum content in the alloy decreases with the increase of the current density of deposition. Smaller sized particles form at higher current density. X-ray analysis, differential scanning calorimetric and measurements of the temperature dependence of electric resistance and magnetic permeability of the powder samples were all used to establish a predominantly amorphous structure of the powder samples formed at the current density of j≥70mA cm-2. The crystalline particle content in the powder samples increases with the decrease of the current density of deposition. Powder heating causes structural changes. The process of thermal stabilization of nickel and molybdenum amorphous powders takes place in the temperature interval from 463K to 573K and causes a decrease in electrical resistance and increase in magnetic permeability. The crystallization temperature depends on the value of current density of powder electrodeposition. Powder formed at j=180 mA cm-2 begins to crystallize at 573K, while the powder deposited at j=50 mA cm-2 begins to crystallize at 673K. Crystallization of the powder causes a decrease in electric resistivity and magnetic permeability. The Curie temperature of the crystallized powders is about 10 K higher than the Curie temperature of amorphous powders

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Section: ________________mentioning

confidence: 99%

The influence of structural changes on electrical and magnetic characteristics of amorphous powder of the nixmoy alloy

Ribić-Zelenović¹,

Rafailović²,

Spasojević³

et al. 2006

SCI SINTER

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“…Amorphous metal alloys, a new class of material with specific properties, are of importance not only for fundamental solid state physics but also in electronics, electrical engineering, metallurgy and other industrial branches [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

The effect of temperature on structural changes of NI55CO45 amorphous powder

2004

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Cobalt and nickel alloy powders were obtained by electrochemical deposition on a titanium cathode from an ammonium solution of cobalt and nickel sulfate. Powders of a specific chemical structure and composition, particle shape and size were obtained by an appropriate choice of electrolysis parameters, current density, deposit growth rate and solution temperature and composition. Within the current density range of 5 - 450 mAcm-2, the current density did not significantly affect the chemical composition of the powders, but had a significant effect on the particle structure, shape and size. Crystal particles formed at a current density lower than 30 mAcm-2. Amorphous powders were obtained at a current density higher than 50 mAcm-2. Structural changes of the obtained amorphous powder of 55mol.% Ni, 45 mol.% Co, pressed under the pressure of 100 MPa, were investigated by measuring the temperature dependence of electrical resistance in isothermal and non-isothermal conditions varying from room temperature to 750°C. The process of thermal stabilization of defects that appeared during pressing occurred within the temperature range of 200-390˚C. The DSC method was used to determine that the powder crystallization process occurred in two stages with peak temperatures of the exothermal maximum in the first and second stage of T1 = 438˚C and T2 = 573˚C, respectively. A distinct correlation between the change of electrical resistance and the crystallization process was established. The reduction of electrical resistively occurs during each crystallization stage

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