Investigating the structural properties of a novel soft magnetic Fe-based amorphous alloy by dynamic mechanical relaxation

• Published in: Intermetallics 2024-03, Vol.166, p.108208, Article 108208
• Main Authors: Rezaei-Shahreza, Parisa, Hasani, Saeed, Seifoddini, Amir, Nabiałek, Marcin, Czaja, Pawel, Śliwa, Agata
• Format: Article
• Language: English
• Subjects: Bulk metallic glasses (BMGs); Internal friction; Mechanical relaxation process; Relaxation; Structural heterogeneity
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2024.108208

Based on the dynamic mechanical spectroscopy, limitations arise when investigating amorphous Fe-based alloys due to their inherent brittleness and the absence of β-relaxation. To address this challenge, precise control over alloy elements and promoting structural heterogeneity at the atomic scale are known as strategies to increase their plasticity. The Fe74B20Nb2Hf2Si2 bulk metallic glass (BMG), enriched with Hf and Nb, is a noteworthy example. This alloy exhibited significant shear transformation zones (STZs) nucleation sites and β-relaxation, attributed to a notable negative mixing enthalpy of mixing Hf and Nb with other alloy elements, along with a favorable Poisson's ratio. By applying Arrhenius' equation, we deduced activation energies of 164 kJ/mol for β-relaxation and 295 kJ/mol for α-relaxation. Remarkably, the modest activation energy associated with β-relaxation suggests a correlation with the expansion of loose packing regions concurrent with the enhancement of β-relaxation within the alloy. Also, using quasi-point defects (QPD) theory, structural heterogeneity characteristics revealed that the correlation factor increases as temperature rises above the glass transition temperature (Tg). This can be attributed to increasing defect concentrations and improved atomic mobility, providing a plausible explanation for the observed phenomenon. As a result, amorphous alloys with the composition Fe74B20Nb2Hf2Si2, exhibiting enhanced plasticity, can be considered promising candidate for various industrial applications. [Display omitted] •In the context of our study:•the dynamic mechanical relaxation behavior of Fe74B20Nb2Hf2Si2 BMG was investigated through the DMA technique.•the QPD theory demonstrated its effectiveness in establishing a robust correlation with our experimental findings.•a direct relationship between thermal energy and atomic mobility was observed, particularly above the glass transition.•the combination of structural heterogeneity and the initiation of STZ sites emerged during β-relaxation phenomena.