Effect of Ni/Cu Content Ratio on Thermal Stability and Mechanical Properties of Zr-based Amorphous Alloy

Zr70Al8Cu22-xNix (x=8.5, 9, 9.5, 10, 10.5, 11) bulk amorphous alloy rods with 2 mm in diameter were prepared by a copper mold casting technique, and the effect of Ni/Cu content ratio on thermal stability and mechanical properties of the Zr-based amorphous alloys were investigated by differential scanning calorimeter (DSC) and uniaxial compression test methods. The results show that the value of supercooled liquid region Delta T-x changes between 80 K and 81 K with the Ni/Cu content ratio increasing; but the Delta T-x is bigger than others when Ni/Cu content ratio is 0.63 and 0.76. When Ni/Cu content ratio is 0.76, the thermal stability is the best and its Delta T-x value is 89 K. The plastic strain exhibits a downward trend with the Ni/Cu content ratio increasing, but there exists an abnormally larger value when Ni/Cu content ratio reaches 0.76, indicating good plasticity, and the compressive yield strength has a downward trend over all with fluctuation but no obvious regularity. And the Young's modulus reaches the maximum value of 80 GPa when Ni/Cu content ratio is 0.63, but that of other alloys changes from 58 GPa to 65 GPa. It is concluded that the plastic strain, compressive yield strength and Young's modulus reach their maximum values when Ni/Cu content ratio is 0.63.