Partially-devitrified icosahedral quasicrystalline phase in Ti33.33Zr33.33Hf13.33Ni20 and Zr30Hf30Ni15Cu10Ti15 amorphous alloys with near equi-atomic compositions

Ti33.33Zr33.33Hf13.33Ni20 and Zr30Hf30Ni15Cu10Ti15 alloys were investigated for their possibility to be formed into a high-entropy alloy (HEA) with a quasicrystalline (QC) structure that contains an icosahedral- (I-) phase. The melt-spun alloys quenched at a circumference speed of 39 m/s were formed into an amorphous single phase. The amorphous alloys annealed up to a temperature between the first and second crystallization temperatures exhibited mixed phases of I- and remaining amorphous phases. Observation of the Zr30Hf30Ni15Cu10Ti15 amorphous alloy heated up to 745 K with transmission electron microscope revealed the presence of precipitates with diameters ranging 10-20 nm. Nano-beam diffraction demonstrated that the precipitates were identified to be the I-phase with the five-, three- and two-fold symmetries. The Ti33.33Zr33.33Hf13.33Ni20 and Zr30Hf30Ni15Cu10Ti15 alloys were not formed into a single quasicrystalline phase as HEAs, but the discussions of the current and early experimental data led to provide the way to approach high-entropy quasicrystalline alloys (HE-QCs).