Soviet Powder Metallurgy and Metal Ceramics

The paper considers the instantaneous stress-strain state in an infinite hollow porous plastic cylinder subjected to simultaneous radial compression and twisting by shear stresses applied to the cylinder surface. It is assumed that the cylinder material obeys a cylindrical yield criterion and associated flow rule. The asymptotic behavior of the equivalent strain rate near the maximum friction surface is studied. It is shown that the distribution of this quantity follows the inverse square root rule near the maximum friction surface. It is noted that the same dependence is observed in the case of incompressible perfect rigid-plastic material. The strain rate intensity factor is found and is compared to that derived from the corresponding perfect rigid-plastic solution.

Two kinds of powder mixtures are used for producing Fe3Al intermetallic alloys. The mixtures are prepared by mixing elemental powders in a drum mixer or grinding in a planetary mill. Compacted and sintered from this mixtures, the billets are subjected to the hot forging and annealing at 1100 and 1300°C. The effect of process conditions on the structure and properties of the materials produced is investigated. It is established that, after hot forging, the strength and fracture toughness of the intermetallic alloy produced from a ground charge are higher than those of the intermetallic alloy produced from non-ground charge. The annealing of the samples at 1100°C causes the decrease in the strength and fracture toughness of both alloys, while increasing the annealing temperature to 1300°C leads to some increase in these characteristics. The hardness of the intermetallic alloy prepared from non-ground powders is higher in comparison with that prepared from pre-ground charge and the annealing and its temperature increase lead to a noticeable decrease in the material hardness.