Electron microscopy techniques are used t o study the domain structure and the mechanism of deformation of the ordered CuAu alloy. Investigations are made into the factors impeding the passage of dislocations across the boundary between domains with differently orientated c-axes. Experiments indicate that the greatest obstacle to the passage of dislocations across such a boundary is the necessity of pairing single dislocations.Mit elektronenmikroskopischen Methoden werden Untersuchungen der Domiinenstruktur und des Deformationsmechanismus in geordneten Cu-Au-Legierungen durchgefuhrt. Die Faktoren werden untersucht, die den Durchgang von Versetzungen durch die Grenzen zwischen Domiinen mit verschieden orientierten c-Achsen verhindern. Die Ergebnisse zeigen, dafl das Haupthindernis fur den Durchgang von Versetzungen durch eine solche Grenze die Notwendigkeit ist, dafl sich die Einzelversetzungen zu Paaren zusammenschlieflen.

The mechanism of deformation of the ordered CuAu alloy is investigated using electron microscopy. The alloy deformation is shown to be accomplished by slipping; a larger degree of deformation involves the mechanism of twinning. The interaction between dislocations and the boundaries of 90° ‐disoriented domains has been studied. It is shown that the interaction between the dislocations and the domain boundaries is responsible for the high deformation strengthening of the ordered alloy.

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To calculate stress intensity factors in elastic pipes with long flaws, the known Cheng-Finnie method is used. A universal description of the mode of behavior of beam is proposed, for which equations of the method of initial parameters with allowance for geometric nonlinearity (effect of axial force on lateral deformation) have been derived and are employed. This allowed us to determine, apparently for the first time, the values of stress intensity factors in thin-walled pipe in a geometrically nonlinear formulation, when increase in pressure leads to their somewhat "retarded" increase. The results have been generalized for a more complex flaw -crack starting from the dent tip.