Abstract:Ni-Cr-Al alloy was deposited by electron beam-physical vapor deposition(EB-PVD) method. The microstructure was investigated on as-deposited and long-term aged alloy. The results indicate that grain on surface of as-deposited alloy is about 185nm in size, and a laminated structure in cross-section is observed. However, after aging for 16 and 120h at 760℃, the laminated structure is dissolved, and the individual grain can be seen clearly. Columnar crystals form on the evaporation side, and exquiaxed grains form on the substrate side. The major precipitate is γ′ phase after prolonged aging at 760℃. Mechanical properties of the Ni-Cr-Al alloy were also studied. The results show that the fracture of as-deposited alloy has mixed type at room temperature, and intergranular fracture among columnar crystals is observed. Compared to that of as-deposited alloy, fracture of alloy after aging for 16 and 120h at 760℃ appears to involve ductile fracture with dimples. 

Key words: Ni-Cr-Al alloy; physical vapor deposition; microstructure; mechanical properties; columnar crystal