Mechanical Behavior of Bulk Amorphous Alloys Reinforced by Ductile Particles at Cryogenic Temperatures

The mechanical behavior of Zr-based bulk amorphous alloy composites (BAACs) was investigated at 77 K. The 5 vol. % Ta-BAAC maintained large plastic strains of $\sim 13\%$ with a 16% strength increase, when compared with that at 298 K. The interaction between shear bands and particles shows that shear extension in particles has limited penetration, and shear bands build up around particles. In addition to on the failure surface of the amorphous matrix, molten characteristics were also found on the surface of sheared particles. Pair distribution function studies were performed to understand the mechanical behavior.

Figure 1

The true stress-strain curves measured at 77 and 298 K (a) as well as in the supercooled liquid region, 693 K for 70 vol. % W-containing-Vit106 BAACs with the SEM image and (b) for 5 vol. % Ta-containing Zr-based BAACs with the backscattering SEM image.

Figure 2

The SEM images of shear bands appear on the side surface of the compressed sample (a) at 298 K and (b) at 77 K; the backscattering SEM images at 77 K showing (c) vein patterns of a more melted area $A$ and less melted area $B$ on a failed amorphous surface, as well as on the surface of sheared Ta particles $C$, $D$, and $E$; and (d) the interaction between shear bands and particles. The investigated samples were 5 vol. % Ta-containing Zr-based BAACs.

Figure 3

SEM images of sheared failure surfaces for as-cast ${\mathrm{Zr}}_{60}{\mathrm{Cu}}_{30}{\mathrm{Al}}_{10}$ BAA containing Ta wire with the dimension of 0.5 mm in diameter. (a) Different failure characteristics of $A$, $B$, and $C$ on a failure Ta surface; (b) molten vein pattern of enlarged area $A$; (c) molten smoother pattern of enlarged area $B$; and (d) ductile failure surface of enlarged area $C$.

Figure 4

Pair distribution function measured at room temperature (dashed line) and 15 K (solid line) for as-cast ${\mathrm{Zr}}_{60}{\mathrm{Cu}}_{30}{\mathrm{Al}}_{10}$ bulk metallic glass.