Processing and characterization of Ni63Cr12Fe4Si8B13 amorphous alloy for the manufacturing of electrical resistances

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Abstract

Amorphous alloys exhibit random atomic arrangements in solid state form, and the phenomena of segregation and grains boundaries are absent. These alloys are obtained by rapid quenching techniques of the melt, with cooling rates of 105 … 106 ℃/s. As a result of the requirement of an extremely high cooling rate, their delivery forms are usually limited to thin films, thin ribbons and, powders. The resistivity of amorphous metals does not depend on temperature as in the case of crystalline ones, exemplified in a situation in which a Pd76Si20Cr4 alloy was heated to a temperature of 4000 K and it was observed that the resistivity in the case of the amorphous alloy increased 3 times higher than in the case of the crystalline alloy. The chemical composition of the processed alloy, in which Si and B are added to stabilize the amorphous phase, leads to an electrical resistivity of 1.72 × 10−6 Ωm and an electrical resistance of 2.9 Ω, which is 3 times higher than that of the Ni-based crystalline alloy, from which the electrical resistances are manufactured.

Introduction

Metallic amorphous alloys belong to the category of advanced materials, both in terms of unique properties and practical uses. Due to their vitreous nature and metastable thermodynamic character, the amorphous alloys show solid-state transformations non-existent in crystalline metallic materials, but present in classical glasses, such as structural relaxation, glass transition, crystallization by devitrification [1].

Most metallic amorphous alloys with practical applicability are obtained by methods of ultra-rapid solidification of the melt with cooling rates higher than 105 K/s [2], [3], [4], [5]. The thickness of these types of alloys does not exceed 60 µm.

The interest for metallic amorphous alloys comes from the particular properties of metallic glasses (mechanical, electrical, magnetic, chemical, thermal) and, especially, from the unusual simultaneous association of these properties. These properties are recommended for applications in various fields such as the aerospace industry, the sports equipment industry, transformer cores, magnetic screens, medical applications, or electrical resistors [1].

The metallic amorphous alloys have a high electrical resistivity at normal temperatures but become superconducting at very low temperatures. The transition to the superconducting state is well marked and occurs in a narrower 0.1 K range [4], [5]. Due to their disordered structure, they have twice the electrical resistivity of crystalline alloys.

The resistivity of amorphous metal alloys has two distinct characteristics: a relatively high electrical resistivity and a low-temperature coefficient of resistivity at ambient temperature, resistivity that changes its sign with the composition. The temperature and composition dependence of resistivity in amorphous alloys is similar to that of liquid alloys.

This paper aims to study the precession and characterization of the metallic alloy with an amorphous structure based on nickel in order to replace the classic materials in the realization of electrical resistances. The materials commonly used for electrical resistors are nickel-based alloys (Ni80Cr20), iron-based alloys (Fe-Cr-Al), Chantal, manganin, and constantan [1], [2], [3].

Section snippets

Experimental procedure

Starting from the chemical composition of the nickel-based crystalline alloys used to make the electrical resistors, the following chemical composition Ni63Cr12Fe4Si8B13 was chosen, by adding Si and B to increase the glass forming ability of the alloy and to improve the thermal stability of the amorphous phase [6].

For the usual resistances used in most applications, Ni-Cr alloy with different chemical compositions is used, but in order to obtain higher properties and specific to amorphous

Results and discussions

The X-ray diffraction pattern shown in Fig. 3 is characterized by the absence of net intensity peaks. There is the presence of two wide peaks, one around the angle 2θ = 20°, and the other around the angle 2θ = 35°. This certifies the amorphous structural state of the obtained ribbons.

Figure 4 shows the characteristic curve obtained by differential thermal analysis with continuous heating.

The DTA curve indicates in a first phase a vitreous transition, followed by a region of supercooled liquid

Conclusions

The metallic amorphous alloy Ni63Cr12Fe4 Si8 B13 was successfully obtained in ribbons form by the melt-spinning method.

This material has a tensile strength of 2670 MPa, the electrical resistance of 2.9 Ω, and electrical resistivity of 1.72 × 10−6 Ω m. Compared to the classic nickel-based alloys with a crystalline structure, an increase of 3 times higher both mechanical strength and electrical resistance was observed.

The metallic amorphous alloys could replace crystalline alloys as they have the

CRediT authorship contribution statement

Dragoş Drăgănescu: Conceptualization, Investigation, Writing - original draft, Writing - review & editing, Methodology. Cosmin Codrean: Methodology, Resources, Validation. Dragoş Buzdugan: Validation, Visualization. Viorel-Aurel Şerban: . Ion Mitelea: Validation, Writing - review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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