OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 3 2022 faults. The values of the parameter β increase by more than an order of magnitude with an increase of the deformation degree up to 60 %. A further increase of the deformation degree leads to a slight decrease in the number of defects of this type. The effect of an increase of the number of twins and stacking faults during cold plastic deformation is known and well-studied for many high-entropy alloys with a FCC lattice [20, 21, 22]. The last stage (the stage of slight decrease) is apparently associated with the saturation of the structure with defects of this type. Furthermore, it can be seen that at the stage of increasing the deformation degree up to 60 %, the material is characterized mainly by the presence of screw dislocations. A further increase of the deformation degree leads to a decrease of the relative fraction of this type of defects. The effect of the dominance of screw dislocations at relatively low strains was demonstrated by Schafl er et al. on the example of commercially pure copper deformed by equal channel angular pressing [23]. According to the obtained results, an increase of the deformation degree leads to a gradual decrease in the fraction of screw dislocations and an increase of the fraction of edge dislocations. A similar effect was also observed in the study of the dislocation structure of the aluminum alloy Al-5.9Mg-0.3Sc-0.18Zr with FCC crystal lattice [24]. This alloy was deformed by high-pressure torsion, and an increase of the number of revolutions from 0.5 to 5 led to a decrease in the proportion of screw dislocations in the system from 30 to 8 %. The obtained results of microstructural studies correlate well with the values of microhardness. It can be seen (Fig. 6) that an increase of the deformation degree leads to a signifi cant increase of the microhardness. It can be noted that the Al0.3CoCrFeNi alloy has a high capacity for work hardening. Conclusions 1. In this study the possibilities of peak profi le analysis methods for assessing defects in the crystal structure are shown by using the high-entropy alloy Al0.3CoCrFeNi as an example. Due to the presence of internal stresses associated with the nature of HEA, it is advisable to take into account the instrumental contribution using a preliminarily prepared annealed alloy of the same composition as the investigated samples. 2. The anisotropy of the elastic properties of the Al0.3CoCrFeNi alloy leads to an error of the approximation of the results by using the classical Williamson-Hall method. Entering of adjustments is an effective way to reduce the approximation error. 3. The smallest approximation error is typical for the modifi ed Williamson-Hall method. The use of this method makes it possible to obtain the most reliable results concerning the defective structure of the Al0.3CoCrFeNi alloy. Plastic deformation by cold rolling leads to an increase of the number of stacking faults and twins. Screw dislocations dominate in the structure of the alloy at a deformation degree up to 60 %, and an increase in the fraction of edge dislocations occurs only with an increase of the deformation degree up to 80 %. This dynamics of defects in the crystal structure is in good agreement with the data provided in the literature. The Al0.3CoCrFeNi alloy has a high tendency to work hardening. References 1. Bataeva Z.B., Ruktuev A.A., Ivanov I.V., Yurgin A.B., Bataev I.A.Obzor issledovanii splavov, razrabotannykh na osnove entropiinogo podkhoda [Review of alloys developed using the entropy approach]. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2021, vol. 23, no. 2, pp. 116–146. DOI: 10.17212/1994-6309-2021-23.2-116-146. 2. Zhang F., Lou H., Cheng B., Zeng Z., Zeng Q. High-pressure induced phase transitions in high-entropy alloys: a review. Entropy, 2019, vol. 21 (3). DOI: 10.3390/e21030239. 3. Wang W.R., Wang W.L., Yeh J.W. Phases, microstructure and mechanical properties of AlxCoCrFeNi high-entropy alloys at elevated temperatures. Journal of Alloys and Compounds, 2014, vol. 589, pp. 143–152. DOI: 10.1016/j.jallcom.2013.11.084. 4. WangW.R.,WangW.L.,Wang S.C., TsaiY.C., Lai C.H.,Yeh J.W. Effects ofAl addition on themicrostructure and mechanical property of AlxCoCrFeNi high-entropy alloys. Intermetallics, 2012, vol. 26, pp. 44–51. DOI: 10.1016/j. intermet.2012.03.005.
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