RMA–CREO処理したCu–Cr–Zr系合金の時効特性に及ぼす二段時効の影響

抄録

The Cu−Cr−Zr alloy is a typical precipitation–strengthening alloy with excellent properties such as high strength, high thermal conductivity, high electrical conductivity, and so on. Recently, there has been an increasing demand for cost reduction, miniaturization and thinning due to the increase in copper bullion prices accompanying the increase in global demand. Therefore, it is required to improve the aging characteristics such as higher strength, higher electrical conductivity and shortening aging time. In this study, we focused on RMA–CREO process, which is a process of forming evaluate organization through introducing remarkable distortion by rotate deformation, as a method to improve properties, and investigated the effect of the two–step aging on properties of this alloy. It was confirmed that the combination of aging of 623 K and 773 K shortened the aging time. As a result of observing the microstructure before the aging using the backscattered electron diffraction method with a scanning electron microscope, it was confirmed that distortions were accumulated in the grains of the specimen subjected to the RMA–CREO process. From the differential scanning calorimetry and the microstructure observation with a transmission electron microscope, it was confirmed that chromium was precipitated in the grains and at the low–angle grain boundaries by the preliminary aging. From the above results, it was suggested that shorten precipitation was promoted by defects such as low–angle grain boundaries introduced by RMA–CREO process became precipitation sites and led to the aging time.