Abstract:To enhance the amorphous phase content and tribological properties of iron-based amorphous alloy coatings, this study proposed a novel strategy for fabricating copper alloy/amorphous gradient coatings on 45# steel substrate. Using coaxial powder-feeding laser cladding technique, single-layer FeCrMoCBY amorphous coatings and copper alloy (CuSn12Ni2)/amorphous double-layer gradient coatings were separately prepared. The effects of laser scanning speed (2000–4000 mm/min) on the microstructure, amorphous phase formation, and tribological properties of the coatings were investigated. The results show that the copper alloy/amorphous double-layer gradient structure significantly accelerates molten pool cooling via the high thermal conductivity of the copper interlayer, reducing the critical cooling rate requirement for amorphous formation. Consequently, the amorphous phase content is substantially improved to 68.9wt%–92.3wt%, showing a remarkable enhancement compared to the single-layer coating. The highest amorphous phase content (92.3wt%) is achieved at a scanning speed of 3000 mm/min. M23C6-type carbide submicron crystals precipitate in the coating and are dispersedly distributed in the amorphous matrix, improving the hardness through a pinning effect. The average microhardness of the gradient coating exceeds 1000 HV0.1 (peak value of 1288.75 HV0.1, which is six times higher than that of the substrate). It is also found that moderate crystallization can enhance hardness of the material. The wear mechanism of the amorphous alloy coating is dominated by abrasive wear. High hardness leads to brittle spallation and the formation of wear debris, which induces secondary ploughing. This study demonstrates that the gradient structure provides more favorable thermodynamic conditions for amorphous phase formation through the thermal-conductivity regulation effect of the copper alloy interlayer, offering new insights for the engineering application of wear-resistant coatings with high amorphous phase content.