Production and characterization of laser cladding coating of Fe66Co7Nb4B23 (at.%) gas-atomized and ball-milled powders

Abstract

In this study, a new Fe66Co7Nb4B23 (at.%) alloy was produced from commercially graded precursors. Gas atomized powder of this alloy was produced, and coarser particles (“splat plates”, size ranges > 5 cm) were subsequently submitted to high-energy ball milling. Laser cladding coating of Fe66Co7Nb4B23 (at.%) gas-atomized and ball milled powders was produced. Powders and laser cladding coatings were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Gas-atomized and ball milled Fe66Co7Nb4B23 (at.%) powders showed a glassy matrix with some crystalline phases such as α-(Fe,Co) and Fe- and Co-containing borides. Both were employed as feedstock powders (<45 μm) to produce single tracks and laser cladding (LC) coating. Optimizing of the LC parameters allowed to obtain and to evaluate single tracks, aiming the production of LC coatings from the optimized parameters. The single tracks were composed of α-(Fe,Co), M2B and M3B phases, and displayed high microhardness, ranging from of 980 ± 150 to 1480 ± 70 HV0.5, depending on the powder and LC parameters. The resulting LC coatings were dense and free from excessive defects such as cracks, porosity and insufficient metallurgical bonding to the AISI 1020 steel substrate. These findings open perspectives to produce protective wear-resistant and affordable coatings on conventional steel components.

Keywords

• Fe-based alloy
• Gas atomization
• High-energy ball milling
• Glassy phase
• Laser cladding
• Coating