Effect of reverse thermoelastic phase transformation on stress of onset of structural deformation in titanium nickelide

The experimental study results of the dependence in the stress value of the onset of the structural deformation on the degree of the reverse phase transformation occurring after the complete direct martensitic transformation in titanium nickelide are described. It is established that these results are qualitatively and quantitatively correctly described in the framework of the model according to which the maximum value of the intensity of the intrinsic inelastic deformation of the martensitic part of the representative volume of the shape-memory alloy is used as a parameter of isotropic hardening.

Model of inelastic deformation of shape memory alloys

Предложен вариант модели фазово-структурного деформирования сплавов с памятью формы, в рамках которого параметром изотропного упрочнения для процесса деформирования по структурному механизму является интенсивность собственной фазово-структурной деформации мартенситной части представительного объема материала. Получено решение задачи об обратном термоупругом фазовом превращении в заневоленном стержне с предварительно заданной растягивающей или сжимающей деформацией. Исследовано влияние на решение значения параметра трансляционного упрочнения.

Stage of concentrated tensile deformation of structural steels

The tensile curves of samples of structural steels and armco-iron in various structural-phase states have been examined. It is shown that the concentrated stage of stretching of metallic materials consists of three periods, the parameters of which (stress σi and degree of deformation δсiн corresponding to the beginning of the period, length δi, rate of stress drop (Δσ / Δδ)i) regularly change with the loss of material plasticity. The periods of the concentrated stage of tension are compared with the fracture zones of the samples and the type of crack.

Effect of small alloying additions on mechanical properties of sintered Al—Sn composites

Composites of the Al—Sn system obtained by liquid-phase sintering of a mixture of doped aluminum powders with tin powder have been investigated. It was found that a small amount of alloying additives (Zn, Mg, Si, Cu) contributed to a considerable strengthening of the aluminum matrix when processing it by the method of equal channel angular pressing, but at the same time reduced the plastic properties. Samples alloyed with 2% Cu demonstrate the maximum strength and minimum ductility.

Production and physical-mechanical properties of amorphous microwires and microcoils

The peculiarities of production and the physical-mechanical properties of amorphous microwires and microcoils made of alloys based on iron and cobalt, which determine advantages of such materials as compared with existing analogs, have been analyzed. The prospects of their application in medicine, microelectronics, as products and elements of promising technology are considered.

Simulation of stress-strain state for ropes of closed construction during tension and torsion

A computer finite-element simulation of the stress-strain state of elements of a closed rope under conditions of joint tension and torsion has been carried out. The redistribution of axial forces and torques in the cross sections of layers during rotation of the rope under the influence of external torque was determined, which leads to a decrease in the safety margin of the rope, a violation of the compatibility of axial and radial movements in the layers and the structural integrity of the rope in the form of wire breakage of the outer layer.