低合金马氏体钢中的ω相

THEωPHASE IN A LOW ALLOY MARTENSITIC STEEL

利用TEM研究了一种低合金钢中马氏体的微结构.研究发现,淬火态的马氏体由铁素体基体和弥散于基体中的高密度纳米小颗粒组成,这种小颗粒的晶体结构可标定为六角结构的ω相.ω相与铁素体基体(α-Fe)的取向关系为:[113]_α//[2113]_ω,(110)_α//(1101)_ω和(211)_α//(0110)_ω,点阵常数a_ω=2^(1/2)a_α,c_ω=3^(1/3)/2a_α.马氏体中的C原子呈非均匀分布,铁素体基体具有很低的C含量,合金中的C原子主要富集在ω相中.

The microstructure of a low alloy martensitic steel has been investigated using TEM. It was indicated that the as-quenched plate and lath martensites consist of ferrite matrix and high density of nanometer-scaled ultrafine particles embedded in the matrix. These particles were designated to beω phase with a primitive hexagonal crystal structure. Theω particles exhibit an orientation relationship with the ferrite （α-Fe） matrix as follows： [113]α//[2113]ω,（110）α //（1101）ω and （211）α//（0110）ω, with lattice parameters of aω=21/2aα , cω=31/2/2aα. The results of the present study suggested that the carbon atoms in the steel are not homogenously distributed in the martensites. The ferrite matrix possesses very low content of carbon, and most of the carbon atoms are concentrated in the ω phase.