The dislocation pipe diffusion of Mn during annealing of 5Mn steel was experimentally investigated using transmission electron microscopy （TEM）. Many dislocations existed inside the ferrite and terminated at the α/...The dislocation pipe diffusion of Mn during annealing of 5Mn steel was experimentally investigated using transmission electron microscopy （TEM）. Many dislocations existed inside the ferrite and terminated at the α/γin- terface of the sample after intercritieal annealing at 650 ℃ for 1 min. Line scans of Mn distribution demonstrated a high Mn concentration in austenite and Mn enrichment at dislocations, indicating that the dislocation pipe diffusion of Mn during intercritical annealing occurred in addition to the γ/α interface diffusion. In-situ TEM observations at 500 ℃revealed that due to Ostwald ripening, large cementite precipitates grew while small cementite precipitates dissolved via Mn diffusion along the dislocations between them.展开更多
Based on grain boundary structural unit model, on the analogy of electric circuit calculation, it was found that the diffusion coefficients of a geneyal intervenient boundary between the delimiting boundaries 1 and 2 ...Based on grain boundary structural unit model, on the analogy of electric circuit calculation, it was found that the diffusion coefficients of a geneyal intervenient boundary between the delimiting boundaries 1 and 2 can be written as D_(11)=[D_((11)1) sin(φ_0-△θ/2)+D_((11)2)]/sinφ_0 D_⊥=D_(⊥1)D_(⊥2)sinφ_0/[sin (φ-△θ)D_(⊥2)+sin(△θ/2)D⊥1)] and D_(11)/D_⊥sin^2φ_0=D_((11)1)/D_(⊥1)sin^2(φ-△θ/2) +[(D_((11)2)/D_(⊥1))+(D_((11)1)/D_(⊥2)]sin(φ_0-△θ/2)sin(△θ/2) +(D((11)2)/D_(⊥2))sin^2(△θ/2) where D_(11) and D_⊥ are the diffusion coefficients pardllel to and perpendicular to the tilt axis, respectively. The subscripts 1 and 2 refer to the delimiting boundaries 1 and 2 respectively, and φ_0, the angle between periodic vectors of the strtictuyal units S_1 and S_2 which composes solely of delimiting boundaries 1 and 2 respectively. The experimental data from Hoffman, Upthegrove and Sinnot and Couling and Smoluchowski are analysed.展开更多
基金Item Sponsored by National Key Research and Development Program of China(2016YFB0700402)National Basic Research Program of China(2010CB630800,2015CB921700)+1 种基金National Natural Science Foundation of China(51671112,51471096,51390471,11374174)Tsinghua University Initiative Scientific Research Program(20141081200,20131089311)
文摘The dislocation pipe diffusion of Mn during annealing of 5Mn steel was experimentally investigated using transmission electron microscopy （TEM）. Many dislocations existed inside the ferrite and terminated at the α/γin- terface of the sample after intercritieal annealing at 650 ℃ for 1 min. Line scans of Mn distribution demonstrated a high Mn concentration in austenite and Mn enrichment at dislocations, indicating that the dislocation pipe diffusion of Mn during intercritical annealing occurred in addition to the γ/α interface diffusion. In-situ TEM observations at 500 ℃revealed that due to Ostwald ripening, large cementite precipitates grew while small cementite precipitates dissolved via Mn diffusion along the dislocations between them.
文摘Based on grain boundary structural unit model, on the analogy of electric circuit calculation, it was found that the diffusion coefficients of a geneyal intervenient boundary between the delimiting boundaries 1 and 2 can be written as D_(11)=[D_((11)1) sin(φ_0-△θ/2)+D_((11)2)]/sinφ_0 D_⊥=D_(⊥1)D_(⊥2)sinφ_0/[sin (φ-△θ)D_(⊥2)+sin(△θ/2)D⊥1)] and D_(11)/D_⊥sin^2φ_0=D_((11)1)/D_(⊥1)sin^2(φ-△θ/2) +[(D_((11)2)/D_(⊥1))+(D_((11)1)/D_(⊥2)]sin(φ_0-△θ/2)sin(△θ/2) +(D((11)2)/D_(⊥2))sin^2(△θ/2) where D_(11) and D_⊥ are the diffusion coefficients pardllel to and perpendicular to the tilt axis, respectively. The subscripts 1 and 2 refer to the delimiting boundaries 1 and 2 respectively, and φ_0, the angle between periodic vectors of the strtictuyal units S_1 and S_2 which composes solely of delimiting boundaries 1 and 2 respectively. The experimental data from Hoffman, Upthegrove and Sinnot and Couling and Smoluchowski are analysed.
