界面热力学与晶界相图的研究进展

胡标, 张华清, 张金, 杨明军, 杜勇, 赵冬冬

Progress in Interfacial Thermodynamics and Grain Boundary Complexion Diagram

HU Biao, ZHANG Huaqing, ZHANG Jin, YANG Mingjun, DU Yong, ZHAO Dongdong

表1 晶界相变和晶界相的相关术语[37]

Table 1 Terminology related to complexion transitions and complexions[37]

Type Definition mode Terminology Meaning Complexion Defined by Congruent Grain boundary characters (R and n) remain invariant, atomic structure transitions geometry transition and composition of the grain boundary core change category Non-congruent Grain boundary characters (R and/or n) change transition Structural Bulk thermodynamic parameters (T, P, μ, etc.) change, interfacial transition thermodynamic parameters (R, n, etc.) remain invariant Faceting A single complexion decomposes into two complexions, the grain transition boundary plane normal n decomposes into n1 and n2 Dissociation A single complexion decomposes into two complexions, a single grain transition boundary dissociates into two new interfaces with the misorientation relationship of R→ R1 + R2 Defined by Premelting A disordered, liquid-like film at a grain boundary forms below the structure and/or transition melting temperature (or solidus) of the bulk phase composition Prewetting A nanolayer complexion with fixed equilibrium thickness forms at the transition interface near the temperature or composition of the wetting transition Adsorption A dramatic change in the composition of an interface in which the transition relative amount of solute increases or decreases significantly Complexion Defined by Intrinsic The complexion exists in pure systems, its composition is identical to category composition complexion the bulk composition Extrinsic The complexion exists in a non-pure system, its composition is in complexion general not equal to the bulk composition Dillon-Harmer Clean A complexion is structurally abrupt, solute segregation is not complexion complexion necessarily entirely absent, but is minimal or is not observed at all, which does not lead to an increase in thickness of the grain boundary core Monolayer The majority of the adsorbed solute is confined to a thickness of a complexion single atomic layer Bilayer The most of the adsorbed solute occupies a thickness of two atomic complexion layers Trilayer The most of the adsorbed solute occupies a thickness of three atomic complexion layers Nanolayer The adsorbed solute occupies a thickness larger than three atomic complexion layers, but which is still finite, fixed and governed by equilibrium thermodynamics, equivalent to intergranular film (IGF) Wetting The bulk wetting film (solid or liquid) at a grain boundary, it has two complexion complexions on each side of the wetting film Defined by Dry A complexion with no adsorbed solute or very little adsorption, thickness and complexion corresponds to the monolayer Dillon-Harmer complexion composition Moist A complexion with multilayer solute adsorption, corresponds to the complexion bilayer, trilayer and nanolayer Dillon-Harmer complexions Wet Refers to the bulk wetting film at a boundary, corresponds to the complexion wetting Dillon-Harmer complexion