Nanoscratch Behavior of Metallic Glass/Crystalline Nanolayered Composites

Nanolayered metallic glass/crystalline composites provide an effective structure for improving the ductility of metallic glasses while maintaining their outstanding strength. The combination of high strength and ductility make these nanocomposites promising materials as wear-resistant coatings. In this work, we experimentally investigated the mechanical properties and nanoscratch behavior of CuZr/Zr metallic glass/crystalline nanolayers. The scratch resistance was highest for the monolithic CuZr, and diminished with decreasing layer thickness for nanolayered coatings, although hardness and elastic modulus were independent of layer thickness. The nanocomposite with a layer thickness of 10nm did not show any signs of failure in spite of compressive strain exceeding 80%. The low shear strength of the CuZr/Zr interface and strain hardening of Zr layers can explain the layer thickness-dependent scratch resistance and outstanding damage tolerance observed. Layered metallic glass/crystalline nanocomposites combine high hardness and resistance to fracture, providing a new design space for the development of effective wear-resistant coatings.