Off-axis insertion of SiC particles in high-speed laser cladding of AlSi7Mg0.6

Aluminium metal matrix composites (Al-MMC) reinforced with SiC particles raise interest for applications such as brake discs for their light weight, wear resistance and low dust emission. However, their production face significant challenges, in particular the homogeneous distribution of the reinforcements, and the formation of brittle aluminium carbides in the melt (casting) or melt-pool (laser cladding). This study explores high-speed laser cladding (HSLC) for Al–SiC MMC, where in-flight selective fusion of aluminium without overheating SiC particles is still a challenge, but the melt-pool life-time is shorter. HSLC with pre-mix Al-SiC powder, as reported for conventional cladding in the literature, is compared to a novel off-axis particles injection system. Compositional and phase analyses were conducted using EDX and X-ray diffraction, and particle fraction and distribution were quantified through image analysis. In all pre-mixed powder trials, brittle carbide precipitates were observed, causing cracks and pores. Adjusting the working distance to vary laser-material interaction time did not suffice. In contrast, separate injection of SiC particles prevented aluminium carbide formation and improved distribution homogeneity. These results demonstrate a viable pathway for multi-material HSLC using a flexible setup compatible with standard laser cladding systems. • Coaxial injection in cladding of Al–MMC SiC causes brittle Al₄C₃ precipitation. • Dual injection prevents carbide formation and ensures matrix integrity. • Dual injection improves SiC catchment efficiency and coating homogeneity. • Adapted powders trajectory might enable high-speed laser cladding of multi-material.