OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 3 2022 the values of the coeffi cient of determination (R2). According to Fig. 5, the values of the coeffi cient 2 R in the case of the classical Williamson-Hall method can be lower than 0.5. This fact indicates that only half of the variance of the values ΔK is described by the model. The entering of adjustments signifi cantly reduces the approximation error. The best result is observed for the modifi ed Williamson-Hall method. a b Fig. 5. The coeffi cient of determination for various peak profi le analysis methods used in this study: the classical Williamson-Hall (WH) method; classical method corrected for the modulus of elasticity (WHEhkl); modifi ed Williamson-Hall (mWH) method. The results for RD (a) and TD (b) directions are presented A number of parameters of the modifi ed Williamson-Hall model make it possible to evaluate the features of defects in the crystal structure of the materials. So, the dynamics of the parameter q (Equation 7) makes it possible to draw conclusions about the change of the relative fraction of edge/screw dislocations. Furthermore, the values of the parameter β (Equation 7) are directly related to the formation of stacking faults and twins in the material. An increase in the number of twins and stacking faults is indicated by an increase in the values of the parameter β. At the same time, the decrease in the parameter q values indicate a decrease in the relative fraction of edge dislocations. The Fig. 6 shows the results of the analysis of the dislocation density and the parameter β depending on the degree of plastic deformation, as well as its relationship with the measured values of microhardness. It can be seen that plastic deformation leads to a signifi cant increase of the number of twins and stacking Fig. 6. Relative fraction of edge dislocations, parameter β and microhardness of the Al0.3CoCrFeNi alloy during cold rolling
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