2020 年 59 巻 1 号 p. 70-75
Work hardening of solid–solution copper alloys is enhanced by dislocation multiplication during plastic deformation, and work hardening coefficients depend on alloying elements. To understand the effects of alloying elements of solid–solution copper alloys on work hardening, we investigated the dislocation evolution of Cu–2 at％ MS （MS＝Mg, Sn, Si） during tensile deformation by using electron backscatter diffraction （EBSD） and X–ray diffraction （XRD）. While the Cu–Mg and Cu–Sn alloys exhibited higher work hardening than the Cu–Si alloy, geometrically necessary dislocation （GND） density, which was evaluated from kernel average misorientation observed in the EBSD measurements, increased similarly with tensile deformation, irrespective of the alloying elements. Thus, the multiplication of GNDs depends not on the alloying elements but on the amount of the plastic deformation. XRD line–profile analysis can analyze total dislocation density including not only GNDs but also statistically stored dislocations （SSDs）. The increase in the total dislocation density of the Cu–Mg and Cu–Sn alloys with the tensile deformation was higher than that of the Cu–Si alloy. This was consistent with their work hardening behaviors. The SSD density was estimated by subtracting the GND density from the total dislocation density, and it was confirmed that the multiplication of SSDs depends on the alloying elements and caused the different work hardening behaviors among the copper alloys. Furthermore, the dislocation mobility in the copper alloys was discussed from the dislocation arrangement parameter, which was obtained from XRD line–profile analysis, to understand why the dislocation multiplications were different with alloying elements. The dislocation mobility of Cu–Mg and Cu–Sn alloys was lower than that of Cu–Si alloy. To compensate the lower dislocation mobility of the Cu–Mg and Cu– Sn alloys, the dislocation multiplication was enhanced.
