Deformation-Induced Destruction of the Long-Range Order in Single Crystals of Ni3Fe Alloy

In the present work, x-ray diffraction and electron microscopy are used to investigate the state of a Ni₃Fe single crystal during plastic deformation. It is demonstrated that the observed destruction of long-range atomic order is accompanied with splitting of superdislocations and generation of single dislocations. The change of the long-range order parameter for single crystals deformed in the [001] direction estimated from the degree of splitting of superdislocations is in good agreement with x-ray measurements of this parameter. The destruction of long-range order for intermediate deformations < 40% is well described by the model of mechanical mixing of the alloy, the main role in which is played by the mechanisms of plane defect generation by shears along slip planes.     

Mechanism of Strain-Induced Breaking the Long-Range Atomic Order in Alloys with the L12 Superlattice Caused by Accumulation of Dislocation Walls

The mechanism of strain-induced breaking the long-range atomic order in alloys with the L1₂ superlattice caused by rearrangement of dislocations in dislocation walls is examined. A mathematical model of strain-induced breaking the long-range atomic order caused by accumulation of dislocation walls is constructed. The dependence of the long-range order parameter on the strain degree is calculated for alloys with high- and low-energy antiphase boundaries.     

Simulation of the process of deformation-induced destruction of long-range order in alloys with an L12 superstructure

Plastic-deformation-induced destruction of long-range order in alloys with an L1₂ superstructure is considered. A mathematical model is suggested which takes into account the following mechanisms that lead to the destruction of long-range order: generation of superdislocations, generation of single dislocations, multiplication of antiphase boundaries (APBs) upon the conservative motion of dislocations, multiplication of APBs upon dislocation climb, formation of APB tubes on superdislocations, generation of point defects, and thermal ordering. A mathematical model of deformation strengthening and long-range order destruction with allowance for the change in the type of shear-forming dislocations from superdislocations to single dislocations is formulated.     

Strain-Induced Disruption of Long-Range Order due to Generation of Superdislocations in L12-Superlattice Alloys

A disruption mechanism for the long-range atomic order in alloys with the L1₂ superlattice is examined. The disruption is caused by an accumulation of superdislocations upon plastic deformation. The rate of increase of the antiphase-boundary area resulting from multiplication of superdislocations is estimated for the cases where the spacing between superpartial dislocations is either constant or strain-dependent. Equations are derived for the rate of change of the degree of long-range order as single-crystalline L1₂-superlattice alloys are subject to deformation.     

Modeling creep in L12-superstructure single crystals

Creep curves for compression and extension under constant loads and constant external stress are calculated using a model of the creep of L1₂-superstructure single crystals. It is shown that features of the creep in alloys with L1₂ superstructure can be explained via the superpositioning of normal and anomalous deformation mechanisms. It is established that during creep, the localization of deformation, which can lead to inverse creep, is important.     

Contributions of the Antiphase Boundary Generation Mechanisms to the Strain Resistance of Single-Crystalline <Emphasis Type="Italic">L</Emphasis>1<Subscript>2</Subscript> — Superlattice Alloys

Using a strain and thermal hardening model for L1₂ — superlattice alloys, contributions of the antiphase boundary generation mechanisms to the strain resistance of the materials under review is estimated to be ∼10%. __________ Translated from Izvestiya Vysshikh Uchenykh Zavedenii, Fizika, No. 7, pp. 8–14, July, 2005.     

Generation of point defects in alloys with theL12 superlattice

The generation of point defects by screw superdislocations in the act of forming a shear zone in single crystals of alloys with the L1₂ superlattice is examined. The fraction of mobile jogs occurring in superpartial dislocations is estimated. A balance equation for point-defect concentrations in this kind of alloy under quasi-static deformation is derived. A mathematical model for work-hardening of these alloys, involving balance equations for dislocations and point defects, is constructed. Tomsk State University of Architecture and Building. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 66–70, January, 2000.