Product Code: PIC2008_203

Laser Producing Ni-Matrix Composite Reinforced by In-Situ Synthesized Particles
Authors:
Mingxing Ma, Tsinghua University, Dept of Mechanical Engineering; Beijing Peoples Republic of China
Jiannan Gu, Tsinghua University; Breijing Peoples Republic of China
Minlin Zhong, Tsinghua University; Beijing Peoples Republic of China
Ruiquan Kang, Tsinghua University, Dept of Mechanical Engineering; Beijing Peoples Republic of China
Wenjin Liu, Tsinghua University, Dept of Mechanical Engineering; Beijing Peoples Republic of China
Weiming Zhang , Tsinghua University; Beijing Peoples Republic of China
Hongjun Zhang, Tsinghua University; Beijing Peoples Republic of China
Presented at PICALO 2008

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 strong-carbide-formation elements and carbon is used in laser producing Ni-matrix composite. By adding stong-carbide-formation elements Ti, Zr, W and C into Inconel 625 powder, Ni-matrix composite reinforced by in-situ synthesized particles can be produced on 45 steel by laser cladding, 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 about HV0.2400. EDAS analysis indicates that there are some proportions of stong-carbide-formation elements Ti, Zr, Nb, Mo, W and C in the particles, so they can be called as complex carbide. Further investigation shows that increasing the total of addition of Ti, Zr, WC and C can decrease the sizes of the carbide particles while increasing the total number of the particles in unit area. It is conducive to the formation of dense and tiny particle phase. Density of the particles will augment if the number of the carbon atom C doubles from the half value of all the other alloying atoms (the total number of alloy atoms replaced by M below), and the average hardness of alloy layer will have a slight drop.When C doubles again, the particles keep the same size, shape,density and distribution, and the average hardness of alloy layer increases obviously. When C doubles to 4M, change of the particles falls in confusion. The influence of W is specially discussed about.