Micro-Mechanical Properties and Corrosion Resistance of Zr-Based Metallic Glass Matrix Composite Coatings Fabricated by Laser Cladding Technology

Laser cladding with ultrafast cooling rates enables effective fabrication of metallic glass matrix composite (MGMC) coatings, significantly enhancing the hardness, corrosion resistance, and mechanical properties of metallic substrates. In this study, a multi-layer Zr65Al7.5Ni10Cu17.5 (at. %) MGMC coating was successfully fabricated by laser cladding technology. The effects of the region-dependent microstructural evolution on micro-mechanical properties and corrosion resistance were systematically investigated. The results indicated that the high impurity content of the powder feedstock promoted the crystallization of the coating during laser cladding. Moreover, coarse columnar crystals in the bottom region of the coating nucleated epitaxially at the coating/substrate interface and propagated along the thermal gradient parallel to the building direction, while dendritic crystals dominated the middle region under moderate thermal gradients. In the top region, fine dendritic and equiaxed crystals deposited in the amorphous matrix, due to the lowest thermal gradient and the highest cooling rate. Correspondingly, nanoindentation results revealed that the top region exhibited peak hardness (H), maximum elastic modulus (E), and optimal H/E ratio, exceeding values in both the bottom region and substrate. Simultaneously, the metallic glass matrix composite coating demonstrated significantly better corrosion resistance than the substrate due to its amorphous phase and protective passive film formation. This work advances amorphous solidification theory while expanding applications of metallic glasses in surface engineering.