In-situ formation and additive manufacturing of nano particulate reinforced metal matrix composites by aser metal deposition

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Particulate Reinforced Metal Matrix Composites (PRMMC) have been extensively investigated in last decades, due to their comprehensive properties and many demanding applications in aerospace, automobile and other industries. Researches in recent years demonstrate that when the particle size is downsized to nanometer scale, the nanoparticulate reinforced MMC (nPRMMC) show excellent strength, hardness, corrosion resistance, thermal resistance, fatigue resistance, high-temperature performance and especially outstanding ductility and fracture toughness, which is incomparable by the micro-scale PRMMCs. Currently, this research area attracts considerable attention world wide. However, three scientific challenges remain not well understood or solved: (I) the extremely difficult uniform dispersion of nanosized ceramic particles in the matrix due to their strong tendency for agglomeration and clustering; (II) the good interface bonding between the nano-scale ceramic particles and the metal matrix; (III) the capability and flexibility for shaping the nPRMMC for bulk structures or coatings. A clear understanding and possible solutions to above issues will have significantly scientific and engineering impacts to explore these advanced nPRMMC materials. Besides the reported approaches in literature, we propose a fundamental investigation project on the in-situ formation and additive manufacturing of nano particulate reinforced metal matrix composites using laser metal deposition (LMD). LMD offers remarkable flexibility and controllability for designed macro/micro structure, composition and geometry, enabling a strong tool for novel material development and shaping. Our research will cover: (1) Formation mechanism of dispersive and uniform nano-scale particles in a metal matrix by two novel routes: (a) In-situ formation of nano-scaled particulates during the solidification process; (b) Dissolution of micro-scale ceramic particulates into nano-scale by laser metal deposition and laser remelting (2) Understanding the mechanisms on homogenous distribution and nano-scale tunability of in-situ formed nanoparticles); (3) Characterization and performance of the nPRMMC; (4) Shaping capability of the nPRMMC by LMD.