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Reobservations of Recrystallization and its Effect on Mechanical and Magnetic Properties in a Severely Cold-Rolled Ni-Based Soft Magnetic Alloy

Mahdavi Azizeh, Mashreghi Ali Reza, Hasani Saeed, Kamali Mohammad Reza

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 2

703--717

EN

Despite of extensive researches for decades, there are many unclear aspects for recrystallization phenomenon in the cold rolled Ni-based alloys. Hence, different thermal cycles were conducted in order to determine microstructural evolutions and its effect on the magnetic and mechanical properties of a 90% cold-rolled thin sheet of a Ni-Fe-Cu-Mo alloy (~80 μm). The obtained results revealed that the recrystallization was started at a temperature of 550°C and was completed after 4 hours. An increase in the number of annealing twins was observed with an increase in annealing temperature, which was due to a bulging and long-range migration of grain boundaries during the discontinuous recrystallization. Ordering transformation occurred in the temperature range of 400-600°C and as a result, hardness, yield strength, and UTS were increased, while with an increase in the annealing temperature these mechanical properties were decreased. Maximum toughness was obtained by annealing at 550°C for 4 hours, while the highest elongation was obtained after annealing at 1050°C, where other mechanical properties including toughness, hardness, yield strength, and UTS were decreased due to the grain growth and secondary recrystallization. Moreover, coercivity and remanence magnetization were decreased from 4.5 Oe and 3.8 emu/g for the cold rolled sample to below 0.5 Oe and 0.15 emu/g for the sample annealed at 950°C, respectively.

2

Effect of tungsten content on glass forming ability and microhardness of Ni-Cr-B-W metallic glasses

Hitit A., Öztürk P., Şahin H., Aşgın A.M.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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Vol. 62, nr 1

5--9

EN

Purpose: The thermal and mechanical properties of Ni-Cr-B-W alloys as a function of tungsten content were studied. Design/methodology/approach: The studies were performed on (Ni49.7Cr14.7B35.6)100-xWx(x:15-40) metallic glass in the form of foils, which have thickness of 20 and 100 μm. Structures of samples wer examined by X-ray diffraction (XRD). Thermal stabilities of the amorphous samples were measured using differential scanning calorimetry (DSC). Microhardness of the amorphous samples were determined by Vicker’s hardness tester. Findings: The XRD investigations revealed that samples of the alloys which have the thickness of 20 μm were amorphous. However, 100 μm samples of the alloys were not amorphous, but contained crystalline phases. Increasing the tungsten addition improved the glass transition and crystallization temperatures of the alloys. Also, microhardness of the alloys improved with tungsten addition. Practical implications: Thermal and mechanical properties of the alloys investigated depend on their tungsten content. Originality/value: This is the first study on Ni-Cr-B-W metallic glass system. Also, because of the production method used, all of the alloys were obtained as amorphous regardless of their composition, so their thermal and mechanical properties could be determined.

3

Ocena własności tribologicznych nowych materiałów narzędziowych na osnowie niklu

Bała P., Krawczyk J., Madej M.

Tribologia

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2011

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nr 4

11-19

PL

W niniejszej pracy przedstawiono nowe materiały na osnowie niklu umacniane związkami faz międzymetalicznych o dużej zawartości węgla. Skład chemiczny nowych materiałów zaprojektowano tak, aby umocnienie osnowy uzyskać w wyniku wydzielania związków międzymetalicznych bogatych Ni oraz Al i Ta, a udział węglików pierwotnych wynosił przynajmniej 20%. Węgliki powinny pozostać stabilne w mikrostrukturze niezależnie od obróbki cieplnej, wpływając korzystnie na odporność na ścieranie. Materiały te mają charakteryzować się przede wszystkim dobrymi własnościami tribologicznymi wykonanych z nich narzędzi do specjalnych zastosowań. Omówiono mikrostrukturę badanych stopów oraz określono rodzaj i udział objętościowy faz węglikowych. Badania tribologiczne wykonano przy temperaturze pokojowej celem określenia roli faz węglików w mechanizmie zużycia. Dla wszystkich badanych stopów wyznaczono wielkość zużycia, współczynnik tarcia oraz określono mechanizm zużycia.

EN

In the paper, the new Ni-based materials with a high carbon content, strengthened by intermetallic compounds, were presented. The chemical compositions of the new materials were designed in such a way as to obtain the matrix strengthening by means of the precipitation of intermetallic compounds rich in Ni as well as Al and Ta and to have the carbide fraction above 20%. Carbides should remain stable in microstructure, regardless of the heat treatment, since they favourably influence an abrasion resistance. Tools use for special application made of these materials should have good tribological properties at elevated temperature. The microstructures and carbides volume fraction of investigated alloys, were described. The reason the tribological test was performed at ambient temperature was to determine the role of the carbides in wear mechanism. The wear level, coefficient of wear, and wear mechanism for all investigated alloys, were described.