Crystallization kinetics and glass-forming ability of bulk metallic glasses Pd40Cu30Ni10P20 and Zr41.2Ti13.8Cu12.5Ni10Be22.5 from classical theory

Abstract

Due to their scientific significance and potential engineering applications, bulk metallic glasses are among the most intensively studied advanced materials. Understanding the glass-forming ability (GFA) of these metallic alloys is a long-standing subject. While a large number of empirical factors have been proposed to correlate with GFA of the alloys, a full understanding of GFA remains a goal to achieve. Since glass formation is a competing process against crystallization, we have performed a systematic analysis on the crystallization kinetics of two known best metallic glass-formers Pd40Cu30Ni10P20 (in at. %) and Zr41.2Ti13.8Cu12.5Ni10Be22.5 based on classical nucleation and growth theory. Our results show that there is a dramatic difference between the two alloys in their nucleation behavior although they possess comparable GFA. Particularly, an extremely sharp nucleation peak (~10^18/m^3 s) is found for Pd40Cu30Ni10P20 around 632 K with a very small half maximum width of 42 K, implying that this alloy is an excellent candidate for nanocrystallization studies. Moreover, we have also found that the GFA of these alloys can be calculated to a high accuracy and precision based on the classical theory, suggesting that the classical theory may be sufficient to account for glass formation mechanism in these metallic alloys.