LASER PRODUCING NI-MATRIX COMPOSITE REINFORCED BY IN-SITU SYNTHESIZED PARTICLES

摘要

Nickel base superalloy has been widely used in key parts in aerospace field for its excellent heat resistance and wear resistance, but some problems always occur in laser cladding layer produced directly with different commerce nickel base superalloy powder as cladding powder, such as lower hardness or bad formation accompanying with higher hardness. The concept on producing Fe-matrix in-situ synthesized particles reinforced composite coatings by means of energy fluctuation and concentration fluctuation in melt by jointly adding of multi strongcarbide-formation elements and carbon is used in laser producing Ni-matrix composite. By adding strongcarbide-formation elements Ti, Zr, W and C into Inconel 625 powder, Ni-matrix composite reinforced by in-situ synthesized particles can be produced by laser cladding or laser alloying, without pores and cracks. The microstructure of the composite characterizes the dispersive and homogeneous precipitation of about 104/mm2 particles in micron size distributed homogeneously on γ-Ni dendritic. The average micohardness of the composite is above HV0.2400.EDAS analysis indicates that there are some proportions of strong-carbide-formation elements Ti, Zr, Nb, Mo, W and C in the particles, so they can be called as complex carbide. The influence of C content and W content in powder joined is specially discussed about.