Study on the structural origins of glass-forming ability and crystallization behaviors in Ni[sbnd]Nb binary alloys

Abstract

The limited glass forming ability (GFA) poses a pervasive challenge in different metallic glass (MG) systems. This study systematically investigated the GFA of NiNb binary alloys, particularly those near the eutectic composition, aiming to explore the intrinsic factors contributing to the disparities in GFA among NiNb binary MGs. The relationship between liquid-like atomic structures and resistance to devitrification is thoroughly examined through the application of k-nearest neighbor machine learning methods. The results indicate that the critical diameter of Ni61Nb39, Ni61.5Nb38.5, and Ni62Nb38 MGs reaches upto 2 mm. An amorphous-amorphous transition is discerned within NiNb MGs exhibiting superior GFAs. These alloys exhibit low thermodynamic driving forces for crystallization, resulting in correspondingly elevated fragility coefficients. Furthermore, the presence of icosahedral-like clusters and the probability density of crystal-like clusters are observed to be intricately linked to GFA and the resistance to crystallization in NiNb MGs. The heightened abundance of crystal-like clusters within the liquid-like domain renders the alloy more susceptible to crystallization. Concurrently, icosahedral-like ordered clusters exert a “pinning effect” on the crystal-like regions, effectively inhibiting crystallization. These results collectively shed light on the fundamental nature of glass formation in NiNb binary MGs.