Investigation On The Physical Properties Of Bulk Metallic Glass Zr₄₈Nb₈Cu₁₂Fe₈Be₂₄ At Low Temperature

Crystallization and glass transition of the bulk metallic glass Zr48Nb8Cu12Fe8Be24 are investigated by electrical resistance, low-temperature specific heat and ultrasonic measurement. The bulk metallic glass Zr48Nb8Cu12Fe8Be24 was prepared successfully by water quenching method. Amorphous nature of the alloys was confirmed by differential scanning calorimetry (DSC) and x-ray diffraction (XRD) experiments. DSC experiment showed the presence of two crystallization processes for this bulk metallic glass at high temperature. Electrical resistance measurement was performed for the amorphous sample and annealed (at different temperatures) samples by using an usual four-probe method from 4.2 to 280 K in a dc mode. A negative temperature coefficient of resistivity (TCR) is found for the amorphous sample and TCR changes its sign from negative to positive with the increase of annealing temperature. The resistance of the as-prepared sample was also investigated from room temperature to 1000 K. The resistivity of sample decreased largely when the first crystallization occurred, increased when the second crystallization occurred and decreased with the increase of temperature after second crystallization.Density and ultrasonic measurement for the amorphous sample and the annealed samples were performed. A supersoftening of long-wavelength transverse acoustic phonons was found in the amorphous Zr48Nb8Cu12Fe8Be24 sample compared to the crystallized samples, which also accompany with the decrease of Young's modulus, shear modulus, Debye temperature, density, bulk elasticity modulus, and increase of Peson's proportion. The samples showed typical properties of supercooled liquid in the supercooled liquid region.Temperature dependence of specific heat for the bulk metallic glass Zr48Nb8Cu12Fe8Be24 and annealed samples were investigated. Specific heat for both amorphous sample and annealed samples may be explained by Debye model. The investigation of magnetic properties showed paramagnetism for both amorphous and crystalline samples at temperature as low as 5 K. The susceptibility (～10-5) for the crystallized sample is lower than the amorphous sample.