Crystallization kinetics of Mg–Cu–Yb–Ca–Ag metallic glasses

The paper presents research into a Mg–Cu–Yb system based metallic glassy alloys. Metallic glasses were prepared using induction melting and further injection on a spinning copper wheel. The effect of alloying by Ag and Ca on the glass forming ability and the kinetics of crystallization of Mg–Cu–Yb system based alloys were studied. The differential scanning calorimeter and X-ray diffractometer were used to investigate the kinetics of crystallization and the phase composition of the samples. An indicator of glass forming ability, effective activation energy of crystallization, and enthalpy of mixing were calculated. An increase of the Ca and Ag content has a positive effect on the glass forming ability, the effective activation energy of crystallization, and the enthalpy of mixing. The highest indicators of the glass forming ability and the thermal stability were found for alloys that contain both alloying elements. The Ag addition suppresses precipitation of the Mg₂Cu phase during crystallization. A dual-phase glassy-nanocrystalline Mg structure was obtained in Mg₆₅Cu₂₅Yb₁₀ and Mg_59.5Cu_22.9Yb₁₁Ag_6.6 alloys after annealing. Bulk samples with a composite glassy-crystalline structure were obtained in Mg_59.5Cu_22.9Yb₁₁Ag_6.6 and Mg₆₄Cu₂₁Yb_9.5Ag_5.5 alloys. A thermodynamic database for the Mg–Cu–Yb–Ca–Ag system was created to compare the process of crystallization of alloys with polythermal sections of the Mg–Cu–Yb–Ca–Ag phase diagram. - Highlights: • New alloy compositions based on Mg–Cu–Yb system were developed and investigated. • Increasing content of Ag and Ca leads to improving GFA. • Bulk samples with a composite glassy-crystalline structure were obtained. • Thermodynamic database for Mg–Cu–Yb–Ca–Ag system was created.