In-situ SR-XRD measurements revealed that the crystallization process in Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass is significantly different from that in tradi-tional glasses. Subsequent heating at 10 GPa converts the sample from amorphous phase into the metastable fcc phase and then leads to the fcc phase back to the amorphous phase, indicating that there exists ’reversible’ phase transition phe-nomena in the material under high pressure and high tem-perature.
Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is annealed at 573 K under 3 GPa and its structural relaxation is investigated by X-ray diffraction, ultrasonic study, compression as well as sliding wear measurements. It is found that after the ZrTiCuNiBe BMG sample was annealed under high pressure, the mechanical properties were improved. Moreover, the BMG with relaxed structure exhibits markedly different acoustic properties. These results are attributed to the fact that relaxation under high-pressure results in a microstructural transformation in the BMG.
Droplets of Zr41Ti14Cu12.5Ni10Be22.5 glass forming alloys with different sizes are solidified in a drop tube containerless processing. Glass transition behavior, crystallization kinetics, and the phase evolution during annealing of the Zr41Ti14Cu12.5Ni10Be22.5 glassy spheres are investigated. The experimental results indicate that the apparent activation energy of the glass transition (Eg=435.5 kJ/mol), and the activation energy of the main crystallization reaction (Ep1 = 249.6 kJ/mol) are obviously different from those of bulk glass samples prepared by water quenched (Eg=559.1 kJ/mol and Ep1=192.5 kJ/mol). The difference is discussed in the view point of the atomic configuration of the liquid state of the metallic glass and nucleation mechanism.
LI Gong, SUN Liling & WANG WenkuiCollege of Material Sciences and Engineering, Yanshan University, Qinhuangdao 066004, China
