Amorphous and dual-phase nanocomposite coatings within the Zr-Cu-B system

• Dual-phase nanocomposite coatings successfully synthesized in the Zr-Cu-B system. • Nanocomposite structure based on ceramic ZrB 2 phase and glassy ZrCu alloy. • Phase segregation promoted by increasing substrate temperature. • Composition-dependent phase segregation revealed by ab initio simulations. • Zr-Cu-B coatings with enhanced plasticity and superior resistance to cracking. Ternary Zr-Cu-B coatings have been prepared using magnetron co-sputtering technique, employing both conventional direct current and high-power impulse magnetron sputtering sources. The study combined detailed experimental structural investigations via X-ray diffraction and electron microscopy with ab-initio simulations of atomic structures for the same compositions of the coatings. A dual-phase nanocomposite structure was identified, consisting of a hard nanocrystalline ZrB 2 phase and a soft amorphous ZrCu phase. By varying the ZrB 2 content (50, 70, and 85 mol.%) while maintaining the same stoichiometry, significant structural evolution was observed. The Zr-Cu-B coatings deposited without heating were amorphous, but simulations revealed composition-dependent segregation tendencies. Increasing substrate temperature promoted phase segregation, leading to the growth of ZrB2 nanocrystals. The size, orientation, and distribution of these nanocrystals were strongly influenced by the fraction of both phases. At 50 mol.% ZrB 2 , the ZrB 2 nanocrystals (1–2 nm) were formed in coatings deposited at a substrate temperature of 450 °C, while higher ZrB 2 fractions enabled segregation at lower temperatures. Mechanical properties, including hardness, reduced Young’s modulus, and plasticity, were closely linked to compositional and structural changes. Compared to binary ZrB 2 coatings, the Zr-Cu-B coatings exhibited enhanced plasticity and superior resistance to cracking, highlighting their potential for advanced applications.