Effects of Ag and Co microalloying on glass-forming abilities and plasticity of Cu-Zr-Al based bulk metallic glasses.

[Display omitted] • (Cu 43 Zr 47 Al 7 Ag 3) 95.5 Co 0.5 BMG exhibits excellent thermal stability and plasticity. • New formed B2-CuZr phase and nanocrystallines improve plasticity. • Toughness mechanisms help design new Cu-Zr-Al BMGs with high mechanical performances. 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. The mechanical performances (i.e., hardness, strength, and plasticity) of the alloys were evaluated, and the plasticization mechanisms of four representative (Cu 46- x Zr 47 Al 7 Ag x) 100 -y Co y specimens were discussed based on the observations of scanning electron microscopy and high-resolution transmission electron microscopy. It is found that (Cu 43 Zr 47 Al 7 Ag 3) 99.5 Co 0.5 bulk metallic glass exhibits excellent thermal stability and improved plasticity after compression tests. The improvement can be attributed to the large amount and density of shear bands, the coexistence of a large area of smooth regions, the vein-like pattern, and the river-like pattern on the fractures. More importantly, the new-formed B2-CuZr phases and nanocrystallines during compressive tests also contribute to the improved plastic deformation ability by exalting the number and density of shear bands. [ABSTRACT FROM AUTHOR]