| 摘要 |
A sheet material of a copper alloy has a chemical composition comprising 1.2 to 5.0 wt % of titanium, and the balance being copper and unavoidable impurities, the material having a mean crystal grain size of 5 to 25 μm and (maximum crystal grain size−minimum crystal grain size)/(mean crystal grain size) being 0.20 or less, assuming that the maximum, minimum and mean values of mean values, each of which is the mean value of crystal grain sizes in a corresponding one of a plurality of regions which are selected from the surface of the sheet material at random and which have the same shape and size, are the maximum, minimum and mean crystal grain sizes, respectively, and the material having a crystal orientation satisfying I{420}/I0{420}>1.0, assuming that the intensities of X-ray diffraction on the {420} crystal plane of the surface of the material and the standard powder of pure copper are I{420} and I0{420}, respectively. |
