Bulk nanostructured materials from severe plastic deformation

Mechanical properties of nanocrystalline materials

Principles of equal-channel angular pressing as a processing tool for grain refinement

1. Introduction 2. The physical metallurgy of nickel and its alloys 3. Single crystal superalloys for blade applications 4. Superalloys for turbine disc applications 5. Environmental degradation: the role of coatings 6. Summary and future trends.

The Superalloys: Fundamentals and Applications

Physics and phenomenology of strain hardening: the FCC case

Dislocation wall and cell structures and long-range internal stresses in deformed metal crystals

It is proposed that, during dislocation glide at low temperatures, both screw and non-screw dislocations annihilate mutually with dislocations of opposite sign approaching on closely neighbouring glide planes. The experimental evidence is summarized and possible mechanisms are discussed. Phenomenological models of dislocation accumulation during deformation, taking into account the annihilation of dislocations, are formulated. The analysis of selected examples of tensile and cyclic deformation of f.c.c. and b.c.c. metal crystals demonstrates that annihilation of edge and/or screw dislocations occurs during strain hardening and can lead to steady state deformation. It follows that the dislocation densities introduced during deformation cannot exceed well-defined upper limits that are distinctly lower than the hypothetical upper limits estimated for the static case. The observations suggest that the critical spacings of dislocation pairs that annihilate are ∼.50–500 nm for screw and ∼ 1·6 nm for ed...

Annihilation of dislocations during tensile and cyclic deformation and limits of dislocation densities

The cyclic hardening and saturation behaviour of copper single crystals

Based on recent experimental observations a realistic model of the evolution of the surface profile of persistent slip bands (PSBs) in fatigued metals is proposed. An essential feature of the model is the production of vacancies by the annihilation of edge dislocations which, combined with irreversible slip processes, leads to an elongation of the PSB parallel to the active slip vector. It is shown that a net extrusion forms rather rapidly. The growth processes and their dependence on temperature are discussed in detail. It is proposed that cracks initiate at the surface steps at the PSB–matrix interface and, at a later stage, also at the notch-peak profile from the random slip processes.

A model of extrusions and intrusions in fatigued metals I. Point-defect production and the growth of extrusions

The present invention relates to a high-temperature part (1) made of a nickel super-alloy having the following composition in wt %: 11-13 % of Cr; 3-5 % of W; 0.5-2.5 % of Mo; 3-5 % of Al; 3-5 % of Ti; 3-7 % of Ta; 1-5 % of Re; the balance consisting of nickel. This invention also relates to a corresponding part (1) made of an alloy having a composition essentially similar to the above-mentioned one and in which the rhenium proportion is replaced with 0.1-5 wt % of ruthenium.

Haël Mughrabi

Papers

Dislocation wall and cell structures and long-range internal stresses in deformed metal crystals

Annihilation of dislocations during tensile and cyclic deformation and limits of dislocation densities

The cyclic hardening and saturation behaviour of copper single crystals

A model of extrusions and intrusions in fatigued metals I. Point-defect production and the growth of extrusions

High-temperature part and method for producing the same