PRECIPITATION AT INTERPHASE BOUNDARIES
PRECIPITATION AT INTERPHASE BOUNDARIES
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DOI：
10.1007/bf02646386
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发表时间：
1978-01-01
期刊：
影响因子：
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通讯作者：
RUSSELL, KC
中科院分区：
文献类型：
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作者：
AARONSON, HI;PLICHTA, MR;RUSSELL, KC
本文讨论了相界面析出的三个问题。(1)关于沉淀形成核的具体相的分类论证是无关紧要的；除非在特殊情况下，临界核通常必须穿透两相形成相间边界。2)生长过程中两相的相对穿透量可能与成核过程中预期的相对穿透量有很大差异；因此，根据对生长形态的观察得出的成核过程的推论是很容易引起误解的。(3) Honeycombe等人的观察表明，碳化物在奥氏体：铁素体边界处的成核主要发生在低能量、不动的边缘宽面，而不是在高能量、可动的边缘立管处，这在理论上是基于防止成核的立管的高速度来解释的。对Ti-Ni合金的实例计算表明，在取代体系中，边缘上升处的析出是可能的，但只有在较低的同源温度下，并且这些边界的迁移仍然由体积扩散控制，而成核则由界面扩散控制。
Three problems in precipitation at interphase boundaries are examined. 1) The classu argument as to the particular phase in which such a precipitate nucleates is shown to be irrelevant; except in a special situation, the critical nucleus must normally penetrate both phases forming the interphase boundary. 2) The relative penetrations into the two phases achieved during growth can be very different than those expected during nucleation; hence, deductions about the nucleation process based upon observations on growth morphologies can be quite misleading. 3) The observations of Honeycombe and others that the nucleation of carbides at austenite: ferrite boundaries occurs predominantly at the low energy, immobile broad faces of ledges rather than at the higher energy, mobile risers of ledges are accounted for theoretically on the basis of the high velocities of the risers preventing nucleation. Example calculations on a Ti-Ni alloy indicate that precipitation at the risers of ledges may become possible in substitutional systems, but only at lower homologous temperatures, and if the migration of these boundaries is still controlled by volume diffusion while nucleation is controlled by interfacial diffusion.