Effect of pressure on nucleation and growth in theZr46.75Ti8.25Cu7.5Ni10Be27.5bulk glass-forming alloy investigated usingin situx-ray diffraction

The effects of pressure up to 10 GPa on nucleation and growth in a typical ${\mathrm{Zr}}_{46.75}{\mathrm{Ti}}_{8.25}{\mathrm{Cu}}_{7.5}{\mathrm{Ni}}_{10}{\mathrm{Be}}_{27.5}$ (vit4) bulk glass-forming alloy during heating, isothermal annealing, and cooling processes were investigated using in situ x-ray diffraction with a synchrotron radiation. It is found that pressure has diverse effects on the nucleation and growth depending on different heat treatments. The constant heating under high pressure can affect the stability of the supercooled liquid state and increase the crystallization temperature. Isothermal high pressure annealing leads to nanocrystallization, which is attributed to the copious nucleation and slow growth velocity. Pressure can enhance the glass forming ability of the alloy by effectively suppressing the crystallization during cooling; bulk glass can be obtained by cooling the melt alloy under high pressure at low cooling rate. The various effects of high pressure on the nucleation and growth and the crystalline phases formed are discussed from the points of view of nucleation kinetics and thermodynamics.