Exceptionally shear-stable and ultra-strong Ir-Ni-Ta high-temperature metallic glasses at micro/nano scales

Abstract

Ir-Ni-Ta metallic glasses (MGs) exhibit an array of superior high-temperature properties, making them attractive for applications at high temperatures or in harsh environments. However, Ir-Ni-Ta bulk MGs are quite brittle and often fracture catastrophically even before plastic yielding, significantly undercutting their high-strength advantage. Here, we show that the Ir-Ni-Ta MGs are not intrinsically brittle, but rather malleable when the feature size is reduced to micro/nano-scales. All tested Ir-Ni-Ta MG micropillars with a diameter ranging from ~500 nm to ~5 µm display a large plastic strain above 25% (the maximum up to 35%), together with a yield strength up to 7 GPa, well exceeding the strength recorded in most metallic materials. The intrinsic shear stability of Ir-Ni-Ta MGs, as characterized by the normalized shear displacement during a shear event, is much larger than those malleable Zr- and Cu-based MGs. Our results suggest that Ir-Ni-Ta MGs are excellent candidates for micro/nanoscale structural applications used at high-temperature or extreme conditions.