The elastic strain energy of growth ledges on coherent and partially coherent precipitates

Chen, G.; Chen, Jhewn‐Kuang; Lee, J. K.; Reynolds, W. T.

doi:10.1007/bf02652308

Cited by 8 publications

(1 citation statement)

References 28 publications

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“…Growth ledges are formed at the matrix/oxide interface through various mechanisms, such as two-dimensional nucleation, spiral growth around screw dislocations, intruder dislocations and so on. 16 Figure 8 a indicates the high magnification image of the region marked by a straight line in Fig. 7 b .…”

Section: Resultsmentioning

confidence: 99%

Characteristics of complex oxides in Co based ODS alloys

Zhang

et al. 2013

Powder Metallurgy

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Co based oxide dispersion strengthening (ODS) alloys strengthened by oxide nanoparticles and c9 precipitates are promising high temperature structural materials. Phase evolution, thermal stability and interfacial structure of the oxides were characterised, and the formation mechanism of the complex oxides was clarified. Co based ODS alloys exhibit inhomogeneous dispersion of the oxides due to the presence of relatively large Y-Al-O and fine Y-Hf-O complex oxides. Oxide particle size was controlled by the relative amount of Y-Al-O and Y-Hf-O oxides. The addition of Hf inhibits the formation of Y-Al-O oxides, resulting in the refinement of the oxides. The coherency of the matrix/oxide interface is size dependent. Large Y-Al-O complex oxides are incoherent with the matrix, while small Y-Hf-O nanoparticles tend to be partially coherent with the matrix. The extremely fine Y 2 Hf 2 O 7 complex oxides demonstrate excellent thermal stability during heat treatment. Based on the observations of partially crystallised nanoparticles and the oxides with core/shell structure, a three-stage mechanism was used to elucidate the formation mechanism of the complex oxides.

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Section: Resultsmentioning

confidence: 99%

Characteristics of complex oxides in Co based ODS alloys

Zhang

et al. 2013

Powder Metallurgy

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Comparison of interfacial structure-related mechanisms in diffusional and martensitic transformations

Aaronson

Muddle

Nie

et al. 2002

Metall Mater Trans A

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Some central problems in understanding the similarities of and the differences between ledgewise martensitic and ledgewise diffusional growth are examined. Martensitic growth can be described in terms of a lattice correspondence and a plane undistorted by the shear transformation. Diffusional growth can be similarly described in some cases but not in others. On the basis of the Sutton-Balluffi definitions of glissile and sessile boundaries, only misfit dislocations (on terraces or risers) or orthogonal sets of disconnections provide a truly sessile interface. When closely spaced structural ledges (now termed "structural disconnections") are present during diffusional growth, they must have been glissile in the formation of a local equilibrium structure during the initial stages of growth. Once they are in local equilibrium and evenly spaced, however, they can only move synchronously because of their local strain interaction. Under these circumstances, extrinsic sources of growth ledges are required to move such interfaces in a diffusional manner. During martensitic growth, however, disconnections in the form of transformation dislocations can move freely in a synchronous manner. Also, on this basis, the apparent (undistorted) habit plane is generally useful in deducing the transformation mechanism during martensite formation, but is only occasionally so during diffusional growth, where only the terrace plane is generally useful.

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