Structure of welded joints obtained by contact weld in nanostructured titanium

The paper presents the research of the weld structure of two Ti specimens of the type VT6 that have nano- and submicrocrystalline structures. Electrical contact welding is used to obtain welds. The acicular structure is formed in the weld area. Two types of defects are detected, namely micropores and microcracks

Structure formation features of large block-shaped samples from the copper and aluminum alloy produced by the wire-feed electron-beam additive technology

In this work the study of the structure of samples made by the wire-feed electronbeam 3D printing from copper C11000 and aluminum alloy AA5056 was carried out. The presence of a dendritic structure typical of this method was revealed, as well as the presence of pores, cracks and other defects that occurred during printing. Mechanical properties of samples cut in the planar section are at a rather low level. The ultimate tensile strength of copper block samples varies between 165 and 187 MPa. The relative elongation of samples without pores is at 18%, but with the presence of pores it decreases sharply to 7%, while the strength is practically not decreased. The samples of alloy AA5056 demonstrate slightly higher mechanical properties: the strength is at the level of 190-192 MPa and the relative elongation is about 16-18%. In samples with defects such as large pores or discontinuities, the strength drops to almost zero

ВЛИЯНИЕ МОДИФИЦИРУЮЩЕЙ СПОСОБНОСТИ РАЗЛИЧНЫХ СОСТАВОВ НА МИКРОСТРУКТУРУ И СВОЙСТВА СПЛАВА АК7ч

The results of experimental studies of the AK7ch Al–Si alloy before and after modifying with compositions—(i) the K2ZrF6 industrial modifier, (ii) modifying mixture based on oxides of refractory metals and cryolite, and (iii) the «Arsal 2120» foreign flux – are presented.It is established that modification of the AK7ch alloy leads to the uniform distribution of eutectics (α-Al + β-Si), structural components, decrease in silicon crystals by a factor of 1,5–2,0 on average, refining, and variation in shape of Fe-containing phases. It is shown that an increase in relative elongation by a factor of 2 and more is characteristics for all modified samples, and the tensile strength, hardness, and density of casts for all the samples are different and has an ambiguous character.Приведены результаты экспериментальных исследований Al–Si-сплава АК7ч до и после модифицирования следующими составами: 1) промышленным модификатором K2ZrF6; 2) модифицирующей смесью на основе оксидов тугоплавких металлов и криолита; 3) зарубежным флюсом «Arsal 2120». Установлено, что модифицирование сплава АК7ч приводит к равномерному распределению эвтектики (α-Al + β-Si), структурных составляющих, уменьшению кристаллов кремния в среднем в 1,5–2,0 раза, измельчению и изменению формы Fe-содержащих фаз. Показано, что для всех модифицированных образцов характерно увеличение относительного удлинения в 2 и более раз, при этом временное сопротивление разрыву, твердость и плотность отливок для всех образцов различны и носят неоднозначный характер

Wrinkling and folding in copper single crystals under compression and sliding

Strain-induced folds on the lateral faces of copper monocrystals generated in compression and sliding tests have been studied using SEM and OM techniques. It has been established that these folds form at different structural scale levels by similar mechanisms related basically to distortion of faces in the vicinity of their end faces during the so-called "lip" formation. Under compression folds have also been formed on the lateral areas bended and on the strain domain boundaries.Keywords: single crystal, wrinkling, folding fragmentation, texture, sliding.</jats:p

Macrosegmentation and strain hardening stages in copper single crystals under compression

The surface deformation-induced pattern (relief) of copper single crystals with the orientation of the compression axis along [111] has been investigated by means of optical, scanning electron and atomic force microscopy. The misorientations between both macroscopic and mesoscopic areas in [111]-single crystals have been determined using the electron back scattering diffraction (EBSD) technique. The macroscopic reorientation has been revealed to rotate the crystalline lattice around the [110] axis. The single crystal has been divided into five macrosegments with their misorientations distributed along the compression axis in a manner that the deformation axis sequentially coincided with the crystallographic directions in the order [111]-[221]-[773]-[110]. Shear by unloaded plane (111) has been observed. The macrolevel deformation up to 25% has been developing as follows: shear by octahedral planes e development of macrobands e reorientation of the central zones e shear by unloaded octahedral plane in the reoriented zones. The steps of this sequence corresponded to the stages of the stress-strain curves

Macrosegmentation and strain hardening stages in copper single crystals under compression

The surface deformation-induced pattern (relief) of copper single crystals with the orientation of the compression axis along [111] has been investigated by means of optical, scanning electron and atomic force microscopy. The misorientations between both macroscopic and mesoscopic areas in [111]-single crystals have been determined using the electron back scattering diffraction (EBSD) technique. The macroscopic reorientation has been revealed to rotate the crystalline lattice around the [110] axis. The single crystal has been divided into five macrosegments with their misorientations distributed along the compression axis in a manner that the deformation axis sequentially coincided with the crystallographic directions in the order [111]-[221]-[773]-[110]. Shear by unloaded plane (111) has been observed. The macrolevel deformation up to 25% has been developing as follows: shear by octahedral planes e development of macrobands e reorientation of the central zones e shear by unloaded octahedral plane in the reoriented zones. The steps of this sequence corresponded to the stages of the stress-strain curves