Strain hardening of alloys with face-centered cubic lattice

A brief review is given of the peculiarities of the strain hardening of face-centered cubic (fee) alloys as compared with pure metals. The fundamental equations connecting the strain hardening characteristics to the quantitative characteristics of the dislocation structure and the slip trace picture are considered in application to alloys with a high friction stress of a nondislocation nature _F. The shape of the strain hardening curves of alloy mono- and polycrystals is analyzed; it is shown that it depends substantially on the stress level F.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 132–150, August, 1976.     

Electron backscatter diffraction study of changes in the grain structure of Ni3Fe ordering alloy upon an A1 → L12 phase transition

The rearrangement of the grain structure of Ni₃Fe alloy upon an A1 → L1₂ phase transition is studied via transmission electron microscopy in combination with the electron backscatter diffraction. It is established that the formation of fresh grain boundaries of general and special types occurs, with the proportion of special-type grain boundaries in the grain boundary ensemble growing. The spectrum of the special grain boundaries changes, due to an increase of the proportion of grain boundaries Σ3 and Σ9. This strengthens the texture of the long-range ordered alloy.     

Energy of planar defects in the Ni<Subscript>3</Subscript>Al phase: Theory and experiment

The Ni₃Al phase with an L1₂ surperstructure exhibits a clearly pronounced positive temperature dependence of the yield stress. The nature of this phenomenon is still not clearly understood. The temperature dependence of the yield stress under consideration is determined, in many respects, by the structure of glide superdislocations and planar defects of these superdislocations involved in the L1₂ superstructure. A critical analysis is made of the current state of the art in the solution of the problem regarding the energy of antiphase boundaries in planes of an octahedron and a cube, as well as the energy of stacking faults in the Ni₃Al phase.     

Electron Diffraction Analysis of the Fracture Zone of Fe–0.45C–17Mn–3Al Steel Subjected to Multicyclic Fatigue Tests

The methods of transmission electron microscopy are used to investigate the structure and phase content of Fe–0.45C–17Mn–3Al steel subjected to multicyclic fatigue tests to failure after intermediate electrostimulation. It is demonstrated that electrostimulation does not change the mechanism of steel failure. An increase in the operating life time of samples after electrostimulation in the intermediate test stage is connected with the hindered -martensitic transformation, the relaxation of stress concentrators, and the reduction of the volume fraction of the critical dislocation (network) substructure in which -martensite is mainly developed.     

The microlevel size of grains and fragments as a factor determining the density of dislocations and disclinations

The role of the size effect in the formation of defect structures in metallic materials was studied experimentally. The objects of study were ultrafine grain (UFG) copper, nickel, and martensitic steel. The effect of the size of grains and fragments on the scalar density of dislocation and the density of partial disclinations was studied by means of transmission electron microscopy (TEM). Measurements were performed for the 100–500 nm range of grain and fragment sizes. Similarities was found in the behavior of grain and fragmented structures.     

Lead,cadmium, and arsenic in commercial algae of the Sea of Japan

The concentrations of toxic elements (arsenic, cadmium, lead) in commercial algae Saccharina japonica and Ahnfeltia tobuchiensis from different habitats of the Sea of Japan have been determined. Bioaccumulation of heavy metals has been analyzed with respect to the habitat and growth conditions. The lead content of Sascharina japonica from all habitats and arsenic content of the same alga species from the Ol’ga Bay, Kievka Bay, and Tatar Strait have been found to exceed maximum permissible levels. Increased lead concentrations have been detected in Ahnfeltia tobuchiensis. Samples of Ahnfeltia tobuchiensis collected from the bottom layer contain more toxic elements than those from the upper layer.     

Study of the crystallography of slip in the alloy Ni3Al

It has been established that cubic slip is an effective mechanism for the strain of the Ni₃A1 alloy even at room temperature. Traces of cubic slip were observed in an electron microscope for all degrees of strain. The critical spalling stress in the plane of the cube is small and approximately 2.5 kg/mm². In a two-phase alloy consisting of segregations, '-phase (Ni₃Al) and a disordered matrix (-phase), the traces of cubic slip generated in the ordered phase which have reached the phase boundary, are even continued into the segregations of the disordered phase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 7, pp. 42–47, July, 1971.