“BUTTERFLY” PRECIPITATES IN δ-TiN_(0.53)→δ’-TiN_(0.53) ORDERING TRANSFORMATION①

“BUTTERFLY” PRECIPITATES IN δ-TiN_(0.53)→δ'-TiN_(0.53) ORDERING TRANSFORMATION

“ＢＵＴＴＥＲＦＬＹ”ＰＲＥＣＩＰＩＴＡＴＥＳＩＮδ－ＴｉＮ_（０．５３）→δ’－ＴｉＮ_（０．５３）ＯＲＤＥＲＩＮＧＴＲＡＮＳＦＯＲＭＡＴＩＯＮＤｕＪｕｎ；ＹａｎｇＧａｉｙｉｎｇ；ＰｏｒｔｉｅｒＲ；ＳｈｉＬｉｋａｉ（ＧｅｎｅｒａｌＲｅｓｅａｒｃｈＩｎ...

The morphology of the hyperstoichiometricδ'-TiN0.53 long-range ordered precipitates during δ-TiN0.53→δ'TiN0.53 ordering transformation was investigated by transmission electron microscopy. It was found for the first time that the δ-TiN0.53 ordered precipitates present a“butterfly”microstructure, which is greatly similar to that found in some martensite transformations, but quite different from the general lamellar microstructures observed in stoichiometric δ'-TiN0.5 and in many other cubic→tetragonal phase transforma tions. In general, δ'-TiN0.53 precipitates consist of three “butterfly”branches whose geometrical symmetry axes are intersected one another at a common point, these “butterflies”are all formed by the three equivalent orientation domains of the δ-TiN0.53 and their growth directions are parallel to < 1 1 1 > directions of the d TiN0.53 matrix .