Key Takeaways & Executive Findings
- •• Cr doping in FeCoNiSiB MPEAAs lowers glass-transition and crystallization temperatures, with optimal soft magnetic properties at 3 at.% Cr (saturation ~0.578 T, coercivity ~5.5 A/m). • Increasing Cr content enhances corrosion resistance, with 8 at.% Cr exhibiting the highest pitting potential (0.288 V) and widest passive region (0.628 V) in 3.5 wt.% NaCl solution. • Microhardness decreases with Cr addition but remains above 810 HV0.5, indicating good mechanical integrity. • The study provides insights into designing multi-principal element amorphous alloys with tailored magnetic and anti-corrosion performance for advanced engineering applications.
Abstract
This research focused on the influences of Cr element doping on the microstructure, thermal stability, microhardness, soft magnetic, and anti-corrosion properties of FeCoNiSiB multi-principal element alloys. The as-received Fe-Co-Ni-Si-B-Cr alloy ribbons made by melt-spinning technique could maintain amorphous nature. The glass-transition temperature and onset crystallization temperature become lower with the addition of Cr, and the highest values are 782.0 K and 821.5 K, respectively. When the Cr content reaches 3at.%, the alloy owns the best soft magnetic performance with the saturation magnetic flux density of ~0.578 T and coercivity of ~5.5 A·m-1 among the studied melt-spun ribbon samples. The microhardness of all alloy ribbons reduces with an increasing Cr content on the whole, and the values are 810 HV0.5 or above. The corrosion behavior of these multi-principal element amorphous alloys containing Cr was also investigated in detail. As the Cr content increases, the corrosion resistance becomes superior and the specimens present the obvious passive regions in 3.5wt.% NaCl solution. The glassy ribbons with 8at.% Cr have the highest self-corrosion potential of -0.340 V and pitting potential of 0.288 V as well as the widest passive region of 0.628 V. Besides, the corroded micrographs of alloy ribbons immersed in corrosive environment lasting 100 h are also presented, which further confirms the above-mentioned experimental results. This research deepens the understanding about the role of Cr element in the microstructure and a series of physical and chemical properties of Fe-Co-Ni-Si-B-Cr multi-principal element amorphous alloys.
1. Introduction
Multi-principal element alloys (MPEAs), also named as medium/high entropy alloys (M/HEAs), usually consist of three or more components with nearly equal elemental ratios [1]. These kinds of alloys become a hot spot in the realm of metal materials and also pioneer a new frontier in the field of metallic materials owing to the potential outstanding and eye-catching performance brought by the extensive composition spaces [2-6].
Amorphous alloys have received increasing attention as advanced materials in recent decades and the first amorphous alloy of Au-Si has been discovered for over half a century. Amorphous alloys can be called metallic glasses (MGs) as well. Because of the unusual combination of excellent performance characteristics, such as exceptional corrosion resistance, high strength and hardness, good soft magnetic and fatigue properties, they are often considered as novel engineering alloys in which the structure is not crystalline [7, 8]. Amorphous alloy with the nominal composition of Fe80P13C7 through rapid quenching from the liquid state was firstly obtained by Duwez in 1960s [9]. In general, they are mostly characterized as “single principal element” or “double principal elements” system, for instance, Fe-based, Co-based, Al-based, ZrCu-based amorphous alloys, among others [10-13]. In recent years, multi-principal element amorphous alloys (MPEAAs) are also developed and put forward, which simultaneously own the “multi-principal element” compositional characteristics of medium/high entropy alloys and the structural characteristics of metallic glasses, i.e., long-term disordered and short-term ordered internal atomic arrangement without grain boundary defects and dislocation [14, 15].
Microdevices and information storage put increasing demands on the functions and properties of magnetic materials with the advance of science, technology, and electronic information [16]. The materials applied in different magnetic devices must have good comprehensive features or prominent multiple functional properties, such as good mechanical properties, excellent thermal stability, prominent corrosion resistance, and good magnetic properties. Corrosion is a natural phenomenon that occurs owing to electrochemical or chemical reactions between metals and aggressive corrosive mediums. Hence, it is vital for amorphous alloys to improve their corrosion resistance and high-temperature service stability on the premise of maintaining their good soft magnetic properties. Qi et al. [17] fabricated a novel series of quinary MPEAAs, namely, Fe25C...
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Shu-yan Zhang, Dan-yue Ma, Pei-pei Shen, Bo Sun, Hua Chen, Zhi-bin Zhang (2025). Effects of Cr element doping on microstructure and performance of quinary FeCoNiSiB multi-principal element alloys. China Foundry. https://doi.org/10.1007/s41230-025-4170-6
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Frequently Asked Questions
What are multi-principal element amorphous alloys (MPEAAs)?
MPEAAs are a class of metallic glasses that combine the multi-principal element compositional characteristics of high-entropy alloys with the amorphous structure of metallic glasses, offering unique properties like high strength, corrosion resistance, and soft magnetic behavior.
How does Cr doping affect the thermal stability of FeCoNiSiB alloys?
Cr doping lowers the glass-transition and onset crystallization temperatures of FeCoNiSiB alloys, with the highest values observed at 782.0 K and 821.5 K, respectively, indicating reduced thermal stability with increasing Cr content.
What is the optimal Cr content for soft magnetic performance in FeCoNiSiB alloys?
The optimal Cr content is 3 at.%, which yields the best soft magnetic properties with a saturation magnetic flux density of ~0.578 T and coercivity of ~5.5 A/m among the studied samples.
How does Cr content influence the corrosion resistance of these alloys?
Increasing Cr content enhances corrosion resistance, with 8 at.% Cr showing the highest self-corrosion potential (-0.340 V), pitting potential (0.288 V), and widest passive region (0.628 V) in 3.5 wt.% NaCl solution.
What are the potential applications of FeCoNiSiB-Cr amorphous alloys?
These alloys are promising for applications requiring combined soft magnetic properties and corrosion resistance, such as in magnetic sensors, transformers, and marine or chemical environments where durability is critical.
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