材料期刊网

RELATIONSHIP BETWEEN PRIMARY MORPHOLOGY AND CRYSTAL STRUCTURE OF CARBIDES GROWING IN SUPERALLOYS

LIU Lin FU Hengzhi SHI Zhengxing Northwestern Polytechnical University , Xi'an , China Dr.LIU Lin Lecturer , Department of Applied Physics , Northwestern Polytechnical University , Xi'an 710072 , China

金属学报(英文版)

The SEM analysis of decply etched specimens of Ni-base superalloys K38 and K19H+Ta in- dicates that both the primary morphologies under normal growth conditions and the final morphologies near equilibrium of MC carbides are octahedral blocks.The classification of MC crystal faces by means of PBC(Periodic Bond Chains)theory confirms that{100}, {110}and{111}are F faces,and that{212}are S faces.The calculations of the attachment energy for each F face show that{111}are most easily appeared.It has also been inferred that one of the MC growth units is a coordination octahedron composed of one metal atom sur- rounded by six carbon atoms.The octahedral growth units can be attached to the growth sur- faces of MC carbides through laver stacking mechanism on the{111}faces.

关键词: carbide , null