Glass-forming ability and crystallization kinetics of Ti20Zr20Cu20Ni20Be20 high-entropy metallic glass probed by ultrafast scanning calorimetry

The glass-forming ability (GFA) and crystallization kinetics of Ti20Zr20Cu20Ni20Be20 high-entropy metallic glass (HE-MG) were investigated. The critical cooling rate (Rc) for glass formation in the HE-MG was determined to be 6000 K/s via flash differential scanning calorimetry (Flash DSC). In comparison to conventional Ti13.8Zr41.2Cu12.5Ni10Be22.5 MG (Vit1), the present HE-MG exhibits much higher crystallization activation energy, indicating that the crystallization process of the HE-MG is much more difficult than Vit1 MG. The crystallization products and phenomena of the HE-MG and Vit1 MG are completely different. The structural change in the HE-MG upon heating occurs in the following sequence: amorphous phase -> amorphous + NiTi-R phases -> NiTi-R + NiTiP + CuTi phases -> NiTi-R + NiTi-P + CuTi + Zr8Ni21 phases, while the Vit1 MG ribbon is composed of Ni10Zr7 + Zr2Cu + Be2Zr + Zr2Ni phases at 785 K and Ni10Zr7 + Zr2Cu + Be2Zr phases at 861 K. Moreover, the HE-MG has a more sluggish crystallization rate than Vit1 MG. The values of the Avrami exponent n for the HE-MG and Vit1 MG are determined to be 1.61 + 0.12 and 1.33 + 0.28, respectively. These different values of n indicate that the nucleation and growth mechanisms of crystalline phase at the first crystallization stage vary significantly between those two metallic glasses. This comprehensive investigation enhances our understanding of the GFA and crystallization kinetics of HE-MGs and provides insights into the design and development of novel multicomponent metallic glass systems.