Effects of Ag and Co Microalloying on Glass-Forming Abilities and Plasticity of Cu-Zr-Al Based Bulk Metallic Glasses

The influences of Ag and Co additions on the thermal stability and glass-forming abilities of twenty (Cu 46- x Zr 47 Al 7 Ag x ) 100 -y Co y ( x = 0, 1, 2, 3, 4 and y = 0, 0.5, 1, 1.5) alloys were systematically investigated by X-ray diffraction and differential scanning calorimeter techniques. It is found that (Cu 43 Zr 47 Al 7 Ag 3 ) 99.5 Co 0.5 bulk metallic glass exhibits excellent mechanical performances after micro-hardness and compressive tests. Plasticization mechanisms of four representative (Cu 46- x Zr 47 Al 7 Ag x ) 100 -y Co y specimens were discussed by scanning electron microscopy and high-resolution transmission electron microscopy methods. It is revealed that the improved plasticity of (Cu 43 Zr 47 Al 7 Ag 3 ) 99.5 Co 0.5 can be attributed to the new-formed B2-CuZr phases and nanocrystallines during compressive tests, which exalts the number and density of shear bands